Spreading accuracy of solid urea fertilisers - Defra, UKrandd.defra.gov.uk/Document.aspx?Document=nt2610_6823_FRP.pdf · Spreading accuracy of solid urea fertilisers Report for Defra

NT2610 Component report for Defra Project NT26

Spreading accuracy of solid urea fertilisers

Steve Parkin (SRI), Bill Basford (ADAS), Paul Miller (SRI)

May 2005

Spreading accuracy of solid urea fertilisers Report for Defra Project NT2610

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Contents 1. EXECUTIVE SUMMARY.......................................................................................................................................... 5

2. INTRODUCTION........................................................................................................................................................ 6 2.1 THE NT2610 PROJECT............................................................................................................................................ 6 2.2 WORK PACKAGES................................................................................................................................................... 7

3. EXPERIMENTAL DESIGN, TREATMENTS AND METHODS .......................................................................... 8 3.1 OBTAINING SAMPLES OF UREA FERTILISERS ........................................................................................................... 8 3.2 MEASUREMENTS OF PHYSICAL PROPERTIES OF FERTILISERS .................................................................................. 9 3.3 MEASUREMENTS OF AERODYNAMIC PROPERTIES OF FERTILISERS .......................................................................... 9 3.4 LABORATORY MEASUREMENTS OF SPREADING CHARACTERISTICS......................................................................... 9 3.5 SELECTION OF PRODUCTS FOR FULL-SCALE TESTING IN A HALL ........................................................................... 11 3.6 METHODS USED IN HALL TESTING ........................................................................................................................ 11 3.7 SELECTION OF PRODUCTS FOR FIELD TESTING ...................................................................................................... 15 3.8 SELECTION OF SETTINGS FOR FULL-SCALE TESTING IN A HALL............................................................................. 17 3.9 SELECTION OF FERTILISER SPREADERS FOR FIELD TESTING .................................................................................. 19 3.10 SELECTION OF SETTINGS FOR FIELD TESTING........................................................................................................ 19 3.11 METHODS USED IN FIELD TESTING........................................................................................................................ 20

4. RESULTS ................................................................................................................................................................... 22 4.1 PHYSICAL PROPERTIES OF FERTILISERS ................................................................................................................ 22 4.2 AERODYNAMIC PROPERTIES OF FERTILISERS........................................................................................................ 22 4.3 LABORATORY MEASUREMENTS OF SPREADING CHARACTERISTICS....................................................................... 23 4.4 INDOOR DISTRIBUTION TESTS IN TEST HALL ......................................................................................................... 23 4.5 FIELD DISTRIBUTION TESTS .................................................................................................................................. 32

5. THEORETICAL CONSIDERATIONS................................................................................................................... 42 5.1 PREDICTING SPREADING PERFORMANCE FROM PARTICLE SIZE AND DENSITY ....................................................... 42 5.2 MODELLING PARTICLE BEHAVIOUR IN THE WIND TUNNEL.................................................................................... 46

6. KEY CONCLUSIONS............................................................................................................................................... 49

7. FUTURE RESEARCH REQUIREMENTS............................................................................................................. 50 7.1 EVALUATION OF METHODS BY WHICH THE APPLICATION OF UREA CAN BE IMPROVED. ........................................ 50

8. ACKNOWLEDGEMENTS....................................................................................................................................... 52

9. REFERENCES........................................................................................................................................................... 53

10. APPENDICES........................................................................................................................................................ 54 10.1 WORK PACKAGES ................................................................................................................................................ 54 10.2 PROJECT MANAGEMENT ....................................................................................................................................... 58 10.3 PHYSICAL CHARACTERISTICS OF CANDIDATE UREA FERTILISERS ......................................................................... 59

10.3.1 2003 Samples.............................................................................................................................................. 59 10.3.2 2004 samples .............................................................................................................................................. 61

10.4 PHYSICAL CHARACTERISTICS OF SELECTED FERTILISERS ..................................................................................... 66 10.5 AERODYNAMIC PROPERTIES OF PRILLED AMMONIUM NITRATE & GRANULAR UREA FERTILISERS. ....................... 68 10.6 DISTRIBUTION AND FLOW PROPERTIES OF FERTILISERS SELECTED FOR FIELD TESTS ............................................ 71 10.7 INFLUENCE OF NETTING PLACED OVER FIELD SAMPLING TRAYS........................................................................... 74 10.8 DIAS, BYGHOLM TESTS MARCH/APRIL 2004 – AN FERTILISERS ........................................................................ 77 10.9 DIAS, BYGHOLM TESTS AUGUST 2004 – UREA FERTILISERS.............................................................................. 78 10.10 SRI FIELD TESTS AUGUST 2004 - GRAN UREA AND AN FERTILISERS ............................................................. 79 10.11 SRI FIELD TESTS OCTOBER 2004 - GRAN UREA AND AN FERTILISERS ........................................................... 80 10.12 CONTOUR PLOT OF STOP DISTANCE VS PARTICLE SIZE AND DENSITY FOR 20 M/S PROJECTION VELOCITY......... 81


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Abbreviations & Symbols

AIC Agricultural Industries Confederation (formerly FMA) AN Ammonium nitrate fertiliser cm centimetre CD Coefficient of Drag (particle)

CPA Crop Protection Association (UK) CSL Central Science Laboratory CV Coefficient of Variation d Particle diameter

DIAS Danish Institute for Agricultural Science FD Drag force (particle)

FMA Fertiliser Manufacturers Association (now AIC) g Acceleration due to gravity

Gran AN Granulated ammonium nitrate fertiliser Gran Urea Granulated Urea fertiliser

hr hour ha hectare

ISO International Standards Organisation kg kilogramme m metre

mm millimetre N Nitrogen

Prilled AN Prilled ammonium nitrate fertiliser PTO Power Take-Off

RB209 Fertiliser recommendations for agricultural & horticultural crops (RB209), MAFF Re Reynolds Number (particle) RH Relative Humidity (%) S Stopping distance (particle)

SEM Standard Error of Mean SP5 Quality test for the spreading of straight nitrogen fertilisers SRI Silsoe Research Institute V Relative velocity (particle) V0 Initial velocity (particle) VT Terminal velocity (particle)

WP Work package ρa Density of air ρp Particle density ηa Dynamic viscosity of air

N.B. Where a number follows the description of a fertiliser e.g. Gran Urea 3.8, the number refers to the median (geometric mean) particle size in millimetres established by sieving.


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Glossary of terms

Blended fertiliser Compound fertiliser produced by the dry mixing of two or more different particulate or powdered materials

Bulk density Density of mass of material. The mass comprises the particles and air spaces between them such that bulk density is determined by size and shape of the particle as well as the density of the particles themselves. Bulk densities can vary between loose, tamped or shaken states and in some materials this variation can be as great as 15%. The bulk densities quoted in the report are intended to represent material delivered to the spreader hopper.

Bout width The distance between successive vehicle tracks when treating a field. This is less than the total width treated by an individual pass of the spreader since deposit patterns are overlapped to achieve satisfactory uniformity. The total width treated is usually around twice the bout width. Other terms that are synonymous are swath width and lane separation.

Complex fertiliser Compound fertiliser where all particles have the same composition Compound fertiliser Product containing more than one of the major nutrients Granulation Method of forming fertiliser particles, usually in the range 2 to 4 mm. The processes

can be sub-divided into slurry and non-slurry methods. In a slurry process, solid particles of fertiliser obtained by re-cycling undersize particles are coated with slurry in successive layers. In a non-slurry process, a liquid component is added to finely divided particles causing them to agglomerate. Most granular products are slightly irregular in shape but some, notably those made by fluidised bed processes, are nearly spherical

Granular fertiliser Solid fertiliser where particles are all produced by granulation. May be complex or blended though the term is sometimes erroneously applied as an alternative to complex.

Hygroscopic Material absorbs moisture from the atmosphere. Median size The particle size where 50% of the material by weight is above that size and 50%

smaller. It is similar to the geometric mean. The median size can vary in some materials and should be treated as a guide. For prilled materials the median size is in the range 2-4 mm.

Particle density The density of the solid material from which the particles are formed. It is therefore independent of particle size and shape and is higher than bulk density. Sometimes called true density.

Prilling A method of particle formation where a molten material is forced under pressure through holes in a disc or rotating bucket. The drops formed fall down a tower where they solidify. Prills tend to be more spherical than granules and slightly smaller.

Straight fertiliser Products containing just one of the major nutrients (nitrogen, phosphate, or potash)


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1. Executive Summary

This project, key to the NT26 programme investigated the physical nature and spreading characteristics of solid ammonium nitrate fertilisers and compared these to solid urea alternatives. The market availability of urea products was identified and their qualities assessed by a series of laboratory tests. The results of these tests indicated suitable materials that were included in indoor test hall and field experiments. Three typical fertiliser spreaders, two twin spinning disc type and one oscillating spout, were selected and used with a wide range of products and settings to determine the relationship between, particle size, particle density and treatment width. Comparisons were made between indoor hall measurements and field tests. The influence of humidity and wind conditions were studied. Trajectory calculations and wind tunnel tests suggested a strong correlation between particle stop distance, particle density, and treated width. This approach was used to determine the size range suitable for applying a granulated urea at a 24 m bout width. This indicated that a good quality urea would be a product which had a median particle size greater than 3 mm and with few fines. It appeared that some granular urea products available to UK farmers in 2004 met this requirement but it appeared that suitable prilled materials were not available. Laboratory distribution tests showed that a good quality granular urea, as defined above, would achieve results that could enable it to achieve the “SP5” quality rating currently used for ammonium nitrate products. Granulated urea was shown to be no more sensitive to increased humidity than ammonium nitrate. Limited field tests did not show any marked difference in the effect of wind on distribution of quality granular urea. Manipulation of bulk samples by sieving enabled the effect of particle size to be studied in the hall tests. The results showed that particle size has a significant effect on spreading width. There was a strong correlation between spreading width and particle stop distance (a parameter developed from basic trajectory theory) and this was confirmed by wind tunnel dispersion tests. A contour plot of spreading width against particle size and density can be used to predict the basic requirements for other solid fertiliser products that could achieve satisfactory performance with existing spreaders at 24 m and 12 m bout width. Correctly prepared, calibrated and operated twin disc spreaders can achieve a satisfactory application of a quality granulated urea at 24 m bout width without the need for further machine improvements. Similarly, oscillating spout spreaders are suitable for use with quality granular urea at 12 m bout width. It would be unwise to make judgements on poorly set–up machines since they were not tested in this study. There is the potential for good quality granulated urea to be spread at bout widths above 24 m but this has not been tested in this study.


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2. Introduction

2.1 The NT2610 project The initial part of the NT26 series of projects identified urea as an alternative to ammonium nitrate as a nitrogen fertiliser. However, a potential problem with the use of urea was identified. This was the application of solid urea at wider bout widths (20 m and above) with existing machinery caused by the lower density of urea when compared to other nitrogen fertilisers. Solid fertilisers are manufactured in two main forms; i. Prilled materials where particles are formed in a molten state and are largely spherical. Prills usually have

a narrow size distribution but there is a practical limit to their mean size. ii. Granular materials are slightly more irregular in shape. They can be larger but usually have a wider size

distribution. Because the physical properties of fertilisers, such as density and particle size, have an influence on their spreading performance, the SP quality assurance scheme for straight nitrogen fertilisers was developed (Miller 1996). The scheme utilises a combination of standardised laboratory tests, measurements using an indoor test rig to simulate the performance of a standardised spinning disc unit. It was developed using a combination of particle trajectory modelling, and distribution tests carried out in halls and in the field. This project draws on the experience grained from that work and other more recent developments to investigate the spreading performance of urea based fertilisers. Project Aim: To show the feasibility or otherwise of spreading a solid urea fertiliser to the same accuracy and

uniformity as currently achieved with ammonium nitrate and to define the characteristics of the urea formulation that would achieve this.

Project Objectives:

1. To determine the range of physical characteristics of solid granular urea fertilisers that may be imported to the UK.

2. To determine the potential for achieving good spreading performance with existing solid urea

fertilisers. This to be based on a study of the relationships between the physical characteristics of different urea fertilisers and the spreading performance of these materials when applied with existing machinery. The work would use two approaches as follows:

2.1 Laboratory rig assessments of spreading performance using a simulated spreading disc

arrangement and wind tunnel tests to quantify aerodynamic behaviour. 2.2 Full-scale distribution pattern measurements in controlled conditions in a test hall.

3. To assess the influence of outdoor environmental factors on the spreading performance of a range of

solid urea fertilisers and hence the feasibility of achieving good spreading performance under realistic operating conditions.

4. To evaluate options for changing the way that fertiliser spreaders are used or simple modifications that

could be made to spreading mechanisms that would enable urea fertilisers to be spread with equivalent


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accuracy to ammonium nitrate. This would be a desk study using the data from the Objectives 1 to 3 above.

5. To collate and analyse data from all parts of the study and report the extent to which spreading

performance equivalent to that currently achieved with ammonium nitrate fertilisers can be attained with materials based on urea or modifications that would make this possible.

6. To define a specification for solid urea fertiliser that would enable it to be spread with existing

machinery at controlled rates and good uniformity. In order to achieve the above objectives the project was organised around seven Work Packages.

2.2 Work packages WP1. Identify and source fertilisers for the study WP2. Assess the range of physical properties for all sourced materials and identify candidate materials for

further study WP3. Indoor (test hall) measurements of distribution patterns with different materials and spreading

mechanisms (e.g. disc, spout) WP4. Outdoor measurements of distribution patterns to determine the effects of weather and other “field”

factors WP5. Indoor (test hall) measurements of spreading distribution patterns in defined circumstances WP6. Evaluation of methods by which the application of urea can be improved WP7. Collation, interpretation and reporting of results Details of each of the Work Packages (as proposed) are given in Appendix 10.1 and Project Management in Appendix 10.2


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3. Experimental design, treatments and methods

3.1 Obtaining samples of urea fertilisers When this project was proposed it was intended that 5 kg samples would be obtained from European sources that might supply the United Kingdom. However, it was difficult to achieve the number of samples originally planned because of commercial availability. Samples were therefore obtained in the U.K. from on-farm sources. In total 15 samples were obtained in 2004. In 2003, as part of work for the earlier NT2601 report (Dampney et al 2003), six granulated urea samples were obtained. To enable the effect of particle size to be determined without the complex interactions that can occur if products are sourced from different manufacturers, it was originally planned that a production run of granulated urea would be obtained from one manufacturer and that either a small pilot plant or a commercial sieving process would be used would be used to obtain a range of particle sizes. A similar process was envisaged for ammonium nitrate test materials to be used as a benchmark comparison. However, because there were difficulties in obtaining sufficient quantities of pilot plant material from fertiliser manufacturers and commercial sieving facilities had further limitations, a different approach was taken. A single commercial granular urea fertiliser with a suitable particle size was sieved to obtain an oversize fraction with a suitable particle size. A supply of a granulated urea fertiliser was obtained with a median particle size of 3.1 mm. To select a larger particle size a motorised grain sieve was modified to handle fertiliser (Fig. 3.1). When used with a slotted 3.5 mm sieve sufficient quantities of oversize material were produced. The median size of the resulting oversize material was 3.8 mm. A comparison granulated ammonium nitrate based fertiliser (nitrogen – sulphur) was obtained that also had a median particle size of 3.1 mm. This product was also sieved using the modified grain sieve to produce an oversize product which again had a median particle size of 3.8 mm. Thus, by sieving it was possible to provide directly comparable granulated urea and ammonium nitrate fertilisers with two different particle sizes.

Fig. 3.1 Sieving stock fertiliser with modified grain sieve to produce oversize product

To examine the performance of prilled materials, stocks of a prilled urea and a prilled ammonium nitrate were obtained. It was hoped that the Prilled Urea would have a larger particle size than the Prilled AN to compensate


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for the density difference but unfortunately in 2004 the only available product had a somewhat similar particle size.

3.2 Measurements of physical properties of fertilisers The measurements of physical characteristics of candidate urea fertilisers were restricted to the key parameters of particle size and bulk density. Sieving was carried out to BS EN1236:1995 and bulk density measured to BS EN1236:1995. In addition, measurements of flowability and angle of repose were carried out to provide baseline data for selected test products; those which were to be used in the indoor hall and field tests. The flowability procedure adopted was that described by Miller (1996). The angle of repose procedure was measured to BS 5551:1989.

3.3 Measurements of aerodynamic properties of fertilisers Because urea has a lower relative density than ammonium nitrate, a test recently developed by SRI (Miller & Parkin 2005) was used to determine the aerodynamic characteristics of urea fertilisers and compare the results with ammonium nitrate. The test uses the SRI chemical application wind tunnel. The wind tunnel is purpose-built for handling chemicals and is constructed in stainless steel. It has a 3 m wide by 2 m high working section that is 7 m long. A small hopper fitted with an electrical vibrator was positioned 1.37 m above the tunnel flow upstream of the working section. A collecting array (2.2 m long by 0.46 m wide) consisting of a series of square section vertical tubes was inset into the tunnel floor 1.5 m downwind of the hopper (see Fig. 3.2). The array had a honeycomb structure and was designed to intercept particles reaching the floor but minimise particle bounce. To obtain the downwind distribution pattern material was collected in a series of trays positioned underneath the collecting array and weighed. An air velocity of 11 m s-1 was selected as being sufficient to winnow the various particle sizes involved but collect the distribution within the working distance of the tunnel.

Fig. 3.2. Aerodynamic tests in SRI wind tunnel; hopper (left) and sampling array with collecting trays in

the tunnel working section (right)

3.4 Laboratory measurements of spreading characteristics The fertilisers identified as being selected test materials, were also subjected to laboratory-based distribution tests. Measurements were made using a test rig established in conjunction with the Fertiliser Manufacturers


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Association (now Agricultural Industries Confederation). The rig was originally constructed to provide data for assuring compliance with the SP5 quality standard for ammonium nitrate fertilisers. Fertiliser is fed from a vibrated hopper, through a calibrated orifice incorporating an agitator and mass flow sensor onto an idealised spinning disc fitted with fixed vanes (Figs. 3.3 & 3.4). Further details of the rig and its performance were given by Miller (1996) and Miller & Parkin (2005).

Fig. 3.3. SRI laboratory fertiliser distribution test rig showing hopper, feed and disc (background) and

collecting channels and sampling beakers (foreground). The white curtains in the foreground are normally closed to contain the test material.

Fig. 3.4. Overhead view of fertiliser distribution test rig showing rotating disc (right) and collecting

channels and sampling beakers (left). The white protective curtains are shown in place. The test provides information relating to flow characteristics, spreading and the risk of particle shatter. Through the use of a standard distribution curve, results from the laboratory distribution tests can provide a direct comparison to the performance of quality ammonium nitrate fertilisers. Laboratory distribution tests are usually conducted using with relative humidity below 75%. However, because urea is well known for being hygroscopic, and this could influence distribution, a series of measurements were carried out using Gran Urea and Prilled AN where the humidity within the laboratory was increased above


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75%. Tests were carried out during a period when natural atmospheric humidity was high. Conditions in the laboratory were varied using a combination of heating and natural ventilation. Using this method it was possible to measure the distribution performance of fertilisers in the relative humidity range 60 to 90%.

3.5 Selection of products for full-scale testing in a hall The products selected for the indoor distribution tests in a hall are shown in Table 3.1. The objective was to test a range of ammonium nitrate and urea products with varying particle size to assess the influence of particle size and density on the spreading pattern achieved by machines with different distribution mechanisms. It was hoped that some tests could be carried out with an ammonium nitrate based fertiliser that had poor spreading characteristics. A material with a source in Eastern Europe was identified but the supplier failed to deliver the fertiliser to the indoor test hall at the Danish Institute of Agricultural Science (DIAS) and substituted a superior material from Lithuania that had similar properties to the UK Prilled AN. It should be noted that the ammonium nitrate and urea tests were not carried out during the same test period because urea and ammonium nitrate materials react and the hall could not be cleaned between bookings. It is DIAS policy to block book urea measurements following a complete clean-up of the hall. Table 3.1 Summary of physical properties of selected test products used in indoor test hall distribution

tests

Fertiliser % N Median Particle Size mm

Bulk Density kg m-3

Prilled AN 34.5 2.33 986

Gran AN 3.1 241 3.09 1103

Gran AN 3.8 241 3.78 1213

Gran Urea 3.1 46 3.13 738

Gran Urea 3.8 46 3.76 747

3.6 Methods used in hall testing

Indoor distribution tests were conducted at the DIAS, Bygholm in March and August 2004. The test hall at Bygholm, described by Persson (1996), is 60 m wide by 80 m long and complies with European requirements. It is one of the largest fertiliser distribution halls in Europe. The hall is air-conditioned. For fertiliser distribution tests the temperature is set to above 12 ºC and the relative humidity is controlled to below 50%.

Spreaders are mounted on a tractor and driven across the sampling area (Fig. 3.5) at normal operating speed. For all the tests reported here the transit speed was 8.3 km/hr.

1 Although based on AN this product has a lower % N than straight AN because it also contains sulphur.


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Fig. 3.5. Tractor and twin disc spreader distributing fertiliser across sampling array in DIAS, Bygholm

test hall Fertiliser was sampled over an area of 1 m deep by 56 m wide and collected in 448 bins each measuring 0.25 m by 0.50 m. (Fig. 3.5) and funnelled into a series of containers mounted on an underground conveyor belt (Fig. 3.6). Following the distribution runs, the containers are automatically transported to weighing stations (Fig. 3.7) where computer interfaced scales measure the quantity of fertiliser collected. The weight of the collected fertiliser in each individual tray was recorded by computer, and the overall spreading pattern displayed using custom software.

Fig. 3.6. Fertiliser sampling bins viewed from above (right), and showing the underground conveyor

(left).


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Fig. 3.7. Fertiliser weighing station with containers, scales and conveyor The normal computer analysis carried out by DIAS provides single and overlapped pattern analysis based on 0.5 m wide by 1 m long samples. To achieve this four adjacent bin measurements (2 ‘rows’ and 2 ‘columns’) are summed. However, to provide comparison data with field measurements based on 1.0 m by 0.25 m trays that are an option specified in ISO 5690/1, raw data was provided by DIAS. This allowed distributions based on 0.25 m wide bins to be calculated. To establish a direct link between indoor hall tests and field tests experiments were carried out using the field trays placed in corresponding positions to the collecting bins. The field trays had sampling areas 1 m long by 0.25 m wide (Fig. 3.8) and were positioned alongside the DIAS sampling bins (Fig. 3.9). Fertiliser collected in the trays was transferred to tared containers and weighed using scales interfaced to a laptop computer running custom data acquisition software. Some protocols used in the UK, involve conducting field tests with trays covered with a wide aperture net (Fig. 3.9). The purpose of the net was to reduce the bounce of particles that inevitably occurs when fertiliser impacts onto the base of the tray causing sampling bias. However, using nets with 24 m spreaders proved difficult. In particular, it was difficult to obtain a satisfactory level of tension in the net over a large area on a smooth floor and this led to variable sized openings. It was decided that tests should be carried out to establish if plain trays could be used in both hall and field tests. If plain trays could be used without significant sampling errors it would speed-up sampling, increasing the number of tests that could be carried out, and improve the quality of data. To test the influence of netting on sampling comparison measurements were carried out in the hall using the three test spreaders and trays with and without covering nets. The results of this work are described in Appendix 3.5. From these tests it was clear that although the use of nets increased the recoveries of fertiliser in the trays for twin-disc spreaders operating at 24 m width this did not influence the width of the distribution or the CVs. The recoveries and CVs of the 12 m oscillating spout spreader were similar. However, since the primary aim of this study was to investigate the performance of spreaders that are designed to apply fertiliser at 24 m bout width, it was decided that satisfactory field tests could be carried using trays without nets and the results compared indoor hall tests by using the same trays indoors.


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Fig. 3.8. Field sampling trays with collected fertiliser granules (left) and covered by a net (right)

Fig. 3.9. Field sampling trays positioned alongside DIAS collecting bins (left), with additional netting

(right)

To enable these direct comparisons to be made, software developed at Silsoe Research Institute to analyse field based fertiliser distributions was modified to accept the raw data input from DIAS software (25 cm wide) or the standard (50 cm wide) data. Tests runs with both software systems using common data established the accuracy of both software packages. With the DIAS sampling bins it was possible to sample the whole spreading pattern including the area occupied by the tractor wheels. With the field sampling trays, because it was not possible to put samplers this area, deposits were calculated using an interpolation procedure. Both DIAS and SRI pattern analysis software calculated CVs from a single run by overlapping patterns. The method adopted was to assume that the measured pattern was mirrored in adjacent runs. In effect, it assumed that the tractor progresses is up and down the field in adjacent bouts and not, for example, in a “round and round” pattern.


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3.7 Selection of products for field testing A sub-set of the products selected for indoor testing in the test hall were selected for use in the field (Table 3.2). The products represented a standard ammonium nitrate fertiliser (Prilled AN) and a candidate granulated urea (Gran Urea 3.1). The Prilled Urea was added to the treatments to demonstrate the effect of a spreading a material with less than ideal characteristics.

Table 3.2. Summary of physical properties of selected test products used in field distribution tests

Fig. 3.10. Amazone ZAM Maxis twin-disc spreader

Fertiliser % N Median Particle Size mm

Bulk Density kg m-3

Prilled AN 34.5 2.33 986

Prilled Urea 46 1.97 763

Gran Urea 46 3.13 738


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Fig. 3.11. Bogballe EX Trend twin-disc spreader

Fig. 3.12. Vicon (Greenland) Variospreader oscillating spout spreader Three machines were selected as representative of the main types of spreader used in UK farming operations. They are shown in Figs. 3.10 to 3.12. Spreading bout widths which cover the majority (75%) of the UK arable area are between 13-24 m. (CSL Sprayer Survey 2002). By far the most common spreader type in use that meets this requirement is the twin disc machine of which both the Amazone and Bogballe are examples. As reported by Dampney et al (2003), in 2000 67% of all UK farms and 72% of those with over 200 ha used spinning disc machines. The UK market leader for spinning disc spreaders is Amazone. Their range includes machines identical in principle to the ZAM series used here or its predecessors. Although it generally uses a one height setting, its performance is modified with minor adjustments made by slight variations in working angle and major adjustments by changing the vane positions on each disc. The Bogballe machine is the third or fourth most popular machine in the UK market and uses machine angle for major adjustment. The disc vanes are perhaps more simple than those used on the Amazone machine. The machine example selected for the tests was electronically adjusted for flow.


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Both machines are claimed by the manufacturers to be able to spread 24 m with a wide range of fertilisers and on certain products beyond 24 m to 30 m or beyond. Both machines were made available through the manufacturers to the DIAS facility in Denmark. From the sprayer survey referred to earlier, 23% of the arable area remains with 13 m bout widths or below. Note that this survey only includes arable land area. Grassland, in particular does not include tramline use and is recognised to have narrower spreading widths i.e.12 m or below. It was therefore decided that a machine typical of use on narrower bout widths should be included in the study. The Vicon Varispreader (Fig. 3.12) was therefore included. The UK importer confirmed that sales of this machine were extremely low. This type of machine is widely used within livestock areas, many being many several years old. Its principle of spreading by using material distributed through an oscillating spout is very different to that of a disc and is not recommended for use beyond 15m. . Dampney et al (2003) reported that 48% of farms with 20-50 ha used oscillating spout spreaders but on farms with over 200 ha this reduced to 8.7%. Machine setting for the Varispreader is very simple with PTO speed, height, flow and spout type being the main variables. No demonstration machine was available from the manufacturers in Holland or their UK agents; therefore a nearly new machine was purchased and transported to and from Denmark for the hall tests. Note: throughout this work the Vicon machine was only ever expected to spread at 12 m bout widths.

3.8 Selection of settings for full-scale testing in a hall Best practice for the operation of any fertiliser spreader requires that the machine be set up according to information available for the fertiliser product with guidance provided by the spreader manufacturer. This normally means that a simple description of the fertiliser brand and product is sought within the machine manufacturer’s instruction book. Such is the development of spreading, with a wide variety of fertiliser products being available; many instruction books have become dated. Therefore, for these tests, each manufacturer’s web site and instruction books were referred to for primary information for spreader settings, e.g. disc, vane, height, feed gate. In each case, prior to any test, the settings made to the machine were verified by two people and test runs were carried out. The DIAS hall automatic facility provides a ‘calibration’ of the machine for each pass as speed and weight of material collected is known within minutes of each run. In addition, as verification for each machine a static calibration was carried out where fertiliser flow issues were measured. On one machine, the Bogalle EX Trend, the machine is controlled by an electronic monitoring system and therefore a static calibration was necessary to verify electronic calibration settings. Once settings were selected and made, a series of test runs were made for each machine/fertiliser to identify repeatability and acceptability of distributions found. The computer facility at DIAS incorporates a large amount of historic data. This combined with operator experience and software, provides optimisation guidance for the settings on each machine. This allowed improvements to be made to the settings, seeking the optimum for each series of runs. Such a facility would not be available to field operators. Normally 3-5 runs sufficed to optimise on any test setting. Once the performance had been verified then the ‘live runs’ required for performance analysis were made; usually 3 runs for each setting. Three rates of nitrogen application were chosen to simulate likely application rates for early, medium or late fertiliser dressings. Linked to this choice was the fact that fertiliser flow rate through a machine can affect its performance with the likelihood of distribution accuracy reducing with application rate.


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The rate of 100 kg N/ha was selected to represent a maximum since it is equivalent to the 300 kg/ha product rate identified in the RB209 guidelines. In order to assess the performance of each spreader a further two reductions were selected; namely 70 and 40 kg N/ha. The latter was chosen to represent the lowest rate application that was considered to be consistent with economic cost of application. Table 3.3. Settings for ammonium nitrate based fertilisers in indoor hall tests

Product Machines Bout Width

Rates Comment

m Kg N /ha Kg /ha 100 290 + field trays 70 203 Amazone 24 40 116

100 290 + field trays 70 203 Bogballe 24 40 116

100 290 + field trays 70 203

Prilled AN 2.2

Vicon 12 40 116

100 492 70 292 Amazone 24 40 167

100 492 70 292

Gran AN 3.1

Bogballe 24 40 167

100 492 70 292 Gran AN 3.8 Amazone 24 40 167

Bogballe 24 100 290 Lithuanian Prilled AN Vicon 12 100 290

Table 3.4. Settings for urea based fertilisers in indoor hall tests

Product Machines Bout Width

Rates Comment

m Kg N /ha Kg /ha 100 217 + field trays 70 157 Amazone 24 40 82

100 217 + field trays 70 157 Bogballe 24 40 82

100 217 + field trays 70 157 40 82

Gran Urea 3.1

Vicon 12

40 167 100 492 70 292 Gran AN 3.8 Amazone 24 40 167


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3.9 Selection of fertiliser spreaders for field testing It was important within the work to ensure that was as little as possible variation between machines used in each of the tests. Ideally the same machines should have been used throughout the study. However, as the field work was to be undertaken in the UK at SRI it was not feasible to transport all three machines to and from Denmark. As a result the Vicon, which was hard to source, was the only individual machine to be involved in all the tests both indoor and field. For the field tests a brand new Amazone ZAM machine was sourced locally to SRI and, with the co-operation of the manufacturer, identical discs to those used in Denmark were mounted on this machine. An Amazone representative attended the first day of the field tests to ensure the settings selected were correctly adjusted and similar to those used in the hall tests. A new Bogballe EX machine was obtained from the UK agents and set-up in accordance with hall settings. The Vicon machine was also set-up as for the hall tests.

3.10 Selection of settings for field testing For the field tests it was decided that only the highest rate of 100kg N/ha was to be used (Tables 3.3 & 3.4). This was because the field tests could not be automated and retrieval of the samples required lengthy manual systems. In addition, the performance of the machines at the two lower rates had already been accurately established in the hall tests. Also, field tests are highly dependent on weather conditions and a greater number of assessments of spreading variability could be made in the time available rather than assessments of the effects of machine flow. Table 3.3. Summary of treatments for the single bout field experiments at Silsoe Research Institute June

2004.

Treatment Spreader Fertiliser Bout width

m

Rate kg N ha-1

Comment

1 Vicon Prilled AN 12 100

2 Vicon Prilled AN 12 100 Using net covered trays

3 Amazone Prilled AN 24 100

4 Bogballe Prilled AN 24 100

5 Amazone Gran Urea 24 100

6 Bogballe Gran Urea 24 100

7 Amazone Prilled Urea 24 100 Selected machine

8 Vicon Gran Urea 12 100


20

Table 3.4. Summary of treatments for the multiple-bout field experiments at Silsoe Research Institute

October 2004

3.11 Methods used in field testing The sampling method adopted for the field test in June 2004 was that adopted in the comparison tests and described in Section 3.5. The field site was a flat area of cut grass sward adjacent to Wrest Park mansion at SRI. A single line of sampling trays was placed normal to the direction of travel of the tractor. Meteorology was monitored locally using an automatic weather station. The direction of travel for the tractor was generally into the wind but short term variability throughout the tests did cause some tests to experience significant cross wind components. As with the hall tests, sections were omitted from the sampling tray transect to allow the tractor to cross the layout. In October 2004 it was intended that the tests would investigate the sensitivity of the AN and Gran Urea applications to field conditions. As a result, a 24 m section from an overlapped application at 24 m bout was sampled. The orientation of the application was such that the spreading was carried out in a cross-wind. (See Section 4.2.)

Treatment Spreader Fertiliser Bout width m

Rate kg N ha-1

Comment

1 Amazone Gran Urea 24 100

Crosswind 3 x 24m

bouts 2 sample

lines 1 replicate

2 Amazone Prilled AN 24 100

Crosswind 3 x 24m

bouts 2 sample

lines 1 replicate


21


22

4. Results

4.1 Physical properties of fertilisers A summary of the physical properties of the candidate urea fertilisers considered in 2004 is shown in Table 4.1. Further details are shown in Appendix 10.3.2. Those products selected for use in the hall and field tests were listed earlier in Tables 3.1 and 3.2. The physical properties of the all the candidate urea fertilisers sampled in 2004 together with those obtained in the earlier study in 2003 (NT2601) are given in Appendix 10.3. The results from urea products selected for laboratory distribution measurements, and tests in the indoor hall and the field are shown in Appendix 10.4. The results from the stock prilled and granular AN products that were selected to provide baseline data are also included in Appendix 10.4. Table 4.1 Physical properties of candidate urea fertilisers sampled from on-farm sources in the UK

during 2004

Sample ID Compound Median particle size mm

Bulk density kg m-3

AL1 Gran Urea 1.83 720 AL2 Gran Urea 3.12 745 AL3 Gran Urea 3.42 750 AL4 Gran Urea 3.32 724 AL5 Gran Urea 3.40 753 AL6 Prilled Urea 2.29 708 AL7 Gran Urea 2.99 723 AL8 Prilled Urea 1.71 731 AL9 Gran Urea 2.93 720

AL10 Prilled Urea 1.89 723 AL11 Gran Urea 2.14 757 AL12 Prilled Urea 2.10 759 AL13 Gran Urea 3.01 726 AL14 Gran Urea 2.57 717 AL15 Gran Urea 3.26 730

It can be seen that the median particle size of Prilled AN was found to be 2.2 mm. To compensate for the lower density of urea, it was hoped that the Prilled Urea sample selected would have a larger particle size. Unfortunately the most suitable prilled product available had a median size of ~ 2.0 mm. It also had significant fines, as can be seen from its size distribution graphs in Appendix 10.4. Thus, although the Prilled Urea selected was the best product that was available on the market in 2004, the laboratory physical tests indicated that it was unlikely to spread well.

4.2 Aerodynamic properties of fertilisers Using the wind tunnel based winnowing test, measurements were made of the characteristics of the selected Gran Urea product and the results compared with Prilled AN. These results are shown in Appendix 10.5. The implications of these measurements for spreading performance will be discussed further in Chapter 5, however


23

the results showed the expected trends with the particle size difference between the Gran Urea and Prilled AN products largely compensated for the difference in particle density (Fig. 10.1 and 10.2). The difference in density between urea and AN is clearly illustrated in Fig. 10.5 where the median particle size of particles is plotted against their downwind distance. At a given distance the urea particles collected were larger than the corresponding AN particles.

4.3 Laboratory measurements of spreading characteristics The results of laboratory tests using the SP5 rig are shown in Appendix 10.6. Tests for the SP5 scheme are usually conducted at when relative humidity is less than 75%. However, the tests for this work included an investigation of the effects of high humidity on distribution. Humidity was varied 60 – 90%. From the results shown in Appendix 10.6 it was clear that Gran Urea had similar flow characteristics to Prilled AN. The distribution characteristics of Gran Urea (Fig. 10.9) and Prilled AN (Fig. 10.10) indicated that both products had acceptable distribution characteristics and the distribution was not significantly altered by increased humidity. Two measurements were made using Prilled Urea at 75% relative humidity (Fig. 10.9). Because significant bridging occurred in the hopper during one of the tests (Fig. 10.8), it was clear that this product was unlikely to spread satisfactorily and further distribution measurements were not taken. This confirmed our view following the measurement of physical properties that the material was unlikely to spread well.

4.4 Indoor distribution tests in test hall In March 2004 tests were made using the AN-based fertilisers and in August 2004 the urea-based fertilisers were tested. In both sets of tests it was necessary to optimise each application to obtain the best spreader set-up for the fertiliser. Use was made of the DIAS fertiliser application optimisation software. This software can indicate from existing data how settings such as vane angle or other machine settings should be varied to improve uniformity. The normal approach adopted for the tests was to optimise the application at 100 kg N/ ha rate and then, using the same machine settings, reduce the application rate and investigate its effect on distribution. The indicator of distribution uniformity was taken to be Coefficient of Variation (CV). Because CV varies with the width of the sampling bins, it is necessary to establish a basis for calculating CV. Because DIAS data is usually based on 50 cm wide bins, the CV based on this basis was used as the primary measure of uniformity for the indoor distribution tests. In all, 91 tests were carried out on ammonium nitrate based fertilisers in March 2004 with a further 85 tests carried out on urea based fertilisers in August 2004. A summary of the optimised AN results is reported in Appendix 10.8 and the optimised urea results in Appendix 10.9. The distribution results from the reference spreader (Amazone) are shown in Table 4.1. An increase in variability with reducing application rate can be clearly seen with all products. The standard Gran Urea fertiliser appeared to provide a satisfactory performance when compared with the reference Prilled AN but increasing the median particle size from 3.1 to 3.8 mm had a variable effect on CV.


24

Table 4.2 Coefficients of Variation for an Amazone twin-disc spreader based on 50 cm wide bins and 24

m bout with varying fertiliser product and nitrogen rate

To provide a direct comparison with field tests, where 25 cm trays were used as standard, the raw DIAS data was transformed and recalculated for 25cm wide bins. This is shown on Table 4.2. Similar trends are seen. The results show the expected increase in CV with decreasing bin/tray width. The Bogballe produced similar CV results to the Amazone although it appeared that it was less sensitive to reduction in application rate. The Vicon produced satisfactory results with both Prilled AN and Gran Urea fertilisers when spreading at 12 m bout width. Table 4.3 Coefficients of Variation for 24 m bout twin-disc and 12 m bout oscillating spout spreaders

based on 25 cm wide bins with varying fertiliser product and nitrogen rate

Mean CV %

Fertiliser

Application Rate

Kg N / ha

Amazone Twin Disc Spreader 24 m bout

Bogballe Twin Disc Spreader 24 m bout

Vicon Greenland Oscillating

Spout 12 m bout

100 10.0 10.0 9.3 70 10.3 9.9 9.7 Prilled AN

2.2 40 18.4 11.7 11.9

100 12.4 7.6 - 70 10.9 10.4 - Gran AN 3.1 40 15.0 14.9 -

100 9.4 8.4 10.6 70 9.4 9.1 11.4 Gran Urea 3.1 40 16.5 11.7 13.2

100 13.6 - - 70 16.9 - - Gran AN 3.8 40 19.0 - -

100 10.1 - - 70 11.9 - - Gran Urea 3.8 40 15.1 - -

Mean CV %

Fertiliser Particle size

mm 100

kg N /ha70

kg N /ha40

kg N / ha Prilled AN 2.2 9.10 9.63 16.40

3.1 11.61 14.17 17.53 Gran AN 3.8 9.06 11.30 12.80 3.1 7.66 7.87 14.42 Gran Urea 3.8 12.06 15.45 18.82


25

Although CV is used as primary measure of uniformity and has been shown to be a useful statistic that could be related to crop yield (England & Audsley 1987) it cannot, as a single statistic, tell the whole story. It is often useful to analyse complete distribution patterns to identify other trends. In Figs. 4.1 to 4.5 distribution patterns are plotted for the products distributed using the reference Amazone spreader. In Figs. 4.6 to 4.10 these patterns are normalised to % collected to enable direct comparisons of spreading performance to be made.

0

50

100

150

200

250

300

350

-30 -20 -10 0 10 20 30

Distance (m)

kg/h

a 40 kg N/ha70 kg N/ha100 kg N/ha

Fig. 4.1. Distribution patterns from an Amazone twin-disc spreader based on 50 cm wide bins for

Prilled AN 2.2 at varying nitrogen rates

0

50

100

150

200

250

300

350

400

450

500

-30 -20 -10 0 10 20 30

Distance (m)

kg/h


Fig. 4.2 Distribution patterns from an Amazone twin-disc spreader based on 50 cm wide bins for Gran

AN 3.1 at varying nitrogen rates


26

0

50

100

150

200

250

300

350

400

450

500

-30 -20 -10 0 10 20 30

Distance (m)

kg/h



AN 3.8 at varying nitrogen rates

0

50

100

150

200

250

-30 -20 -10 0 10 20 30

Distance (m)

kg/h



Urea 3.1 at varying nitrogen rates


27

0

25

50

75

100

125

150

175

200

225

250

-30 -20 -10 0 10 20 30

Distance (m)

kg/h



Urea 3.8 at varying nitrogen rates

0

50

100

150

200

250

300

350

400

-30 -20 -10 0 10 20 30

Distance (m)

%

40 kg N/ha70 kg N/ha100 kg N/ha

Fig. 4.6 Normalised distribution patterns from an Amazone twin-disc spreader based on 50 cm wide

bins for Prilled AN 2.2 at varying nitrogen rates


28

0

50

100

150

200

250

300

350

400

-30 -20 -10 0 10 20 30

Distance (m)

%



bins for Gran AN 3.1 at varying nitrogen rates

0

50

100

150

200

250

300

350

400

-30 -20 -10 0 10 20 30

Distance (m)

%



bins for Gran AN 3.8 at varying nitrogen rates


29

0

50

100

150

200

250

300

350

400

-30 -20 -10 0 10 20 30

Distance (m)

%



bins for Gran Urea 3.1 at varying nitrogen rates

0

50

100

150

200

250

300

350

400

-30 -20 -10 0 10 20 30

Distance (m)

%



bins for Gran Urea 3.8 at varying nitrogen rates From Figs. 4.1 to 4.10 it can be see that as application rate reduces the central peak in the distribution pattern increases and there is decrease in the shoulder that occurs in the pattern around ± 10 m from the centreline. By examining Figs. 4.1 to 4.5 it was evident that the measurements were sensitive enough to record common features in the distribution pattern which result from the spreading mechanism and guide vanes. Comparisons between Figs. 4.7 and 4.8 and Figs. 4.9 and 4.10 showed that increasing particle size increases the width of the pattern but that increasing the median particle size from 3.1 mm to 3.8 mm had a greater effect with ammonium nitrate based products than with the urea based products. Although all tests with the twin-disc spreaders were carried out using settings optimised for a 24 m bout width, a useful indicator of the sensitivity of the optimisation to errors in, for example bout marking or driving, can be


30

achieved by plotting the variation in CV with bout width. Figs. 4.11 and 4.12 show the relationship between the mean CV for the optimised applications and bout width and the products used in the hall tests. A key area is the rate of increase of CV at bout widths greater than the target 24 m. If there is a large increase in CV at bouts just larger than the optimum then it is likely that the application is not robust. In Fig. 4.11, with the Amazone spreader, the ammonium nitrate applications provided a flatter profile indicating more robust applications. Also, apart from the Gran Urea 3.8 application which appears to have not been particularly well optimised, increasing particle size decreased sensitivity. In Fig. 4.12, with the Bogballe spreader, the picture is less clear with all applications giving a similar profile.

0

5

10

15

20

25

30

35

20 22 24 26 28 30 32

Treatment width m

Coe

ffice

nt o

f Var

iatio

n %

AN 2.2AN 3.1AN 3.8G Urea 3.1 G Urea 3.8

Target Treatment

Width

Fig. 4.11 Coefficient of Variation as a function of bout width for an Amazone twin-disc spreader based

on 50 cm wide bins and 100 kg N / ha with varying fertiliser product. Error bars are SEM.

0

5

10

15

20

25

30

35

20 22 24 26 28 30 32

Treatment width m

Coe

ffice

nt o

f Var

iatio

n %

AN 2.2AN 3.1G Urea 3.1

Target Treatment

Width

Fig. 4.12 Coefficient of Variation as a function of bout width for a Bogballe twin-disc spreader based on

50 cm wide bins and 100 kg N / ha with varying fertiliser product. Error bars are SEM.


31

It was clear that to fully examine the results not only required a measure of treatment uniformity required (CV) but also a measure of treatment width. This would allow the effects of particle size and density to be explored more fully and also provide a link to modelling and calculation. A measure of treatment width based on the difference between the 10 and 90 percentiles of the cumulative distribution was developed. The basis of this calculation is illustrated in Fig. 4.13 using a typical measured distribution. A cumulative distribution is constructed from the deposit (frequency) pattern and a treatment width based on the difference between the 10 and 90 percentiles is calculated using interpolation. The treatment widths of the various Amazone treatments are shown in Fig. 4.14. From the results it is clear that particle size and density influence treatment width and that pro rata the heavier AN based fertilisers have a wider treatment width than urea based fertilisers and that increasing particle size increases treatment width. Also, the effect of particle size appears to be more marked with AN based fertilisers than urea based fertilisers. A feature, noted in Section 3.7, is the influence of application rate. At lower application rates the influences of density and particle size on treatment width are clear but at higher rates they can become masked by what could be the effects of mass flow.

0

10

20

30

40

50

60

70

80

90

100

-24 -20 -16 -12 -8 -4 0 4 8 12 16 20 24

Distance (m)

Cum

lativ

e %

0.0

0.5

1.0

1.5

2.0

2.5

Freq

uenc

y %

90 -10 % treatment idth

Fig. 4.13 Example of frequency and cumulative distributions illustrating the calculation of the 90-10 %

treatment width


32

0 5 10 15 20 25 30

100

70

40

App

licat

ion

kg N

/ha

90-10% treatment width m

AN 3.8mmGran Urea 3.8 mmAN 3.1 mmGran Urea 3.1 mmAN 2.2 mm

Fig. 4.14 Variation of 90-10 % treatment width from an Amazone twin-disc spreader based on 50 cm

wide bins with fertiliser product and nitrogen rate

4.5 Field distribution tests A summary of the results from the field tests carried out at Silsoe Research Institute in June 2004 is given below. As indicated in Section 3.10 the aim was to measure single bout distributions and analyse overlapped distributions using software. Details of the single bout tests, including meteorological conditions, are given in Appendix 10.10. From Table 4.3 it can be seen that distributions from the twin-disc Amazone and Bogballe machines produced similar or slightly lower CVs when applying Gran Urea than when applying Prilled AN. As expected from the laboratory tests the Prilled Urea distributions produced significantly higher CVs than Prilled AN. Two pairs of distributions from the Vicon oscillating spout spreader showed slightly higher CVs in the first instance and significantly high CVs in the second. The disparity between the pairs of results cannot easily be explained. Typical distributions from each of the fertilisers tested are shown in Figs. 4.15 to 4.21 and typical overlapped patterns are shown on Figs. 4.22 to 4.28. Examination of the distribution patterns in Figs. 4.17 to 4.19 and the overlapped patterns in Figs. 4.22 to 4.23 shows and that the uneven application with Prilled Urea results from the secondary peaks in the distribution around 12 m from the tractor centre line and the large peak on the centre line. The latter is probably the result of the large fraction of fines in the product (Appendix 10.4). There was also some evidence of secondary peaks in the Bogballe application made with Prilled AN (Fig.4.19) although this was not particularly evident in the overlapped pattern (Fig. 4.26). The first pair of Vicon results with Gran Urea (Figs. 4.20 and 4.27) showed that the spreader achieved a satisfactory spread and pattern with a 12 m bout and the Prilled AN results with the Vicon spreader were also satisfactory (Figs. 4.21 and 4.28). However, the second set of results (Figs. 4.29 and 4.30) indicated that reduced deposits around 5 m from the tractor contributed to the higher CVs shown in Runs 26 and 27 in Table 4.3. Although the reasons for this reduction in deposit are not easily explained the effect is symmetrical and is unlikely to be associated with crosswind effects. Because the runs that produced the lower deposit and higher CV took place at the end of the day, the possibility of humidity effects was considered. Whilst it is always possible that the fertiliser became “damp” whilst in the hopper as air temperature dropped and humidity rose, the relative humidity during the time these


33

runs took place was ~65%. Because this was below the 75% threshold the influence of humidity was considered unlikely. Table 4.4 Summary results of optimised field distribution measurements from twin-disc and oscillating

spreaders with Urea and AN fertilisers.

Run Product Target Rate Machine Bout CV Recovery

# N kg/ha kg/ha m % kg/ha 3 Gran Urea 100 215 Amazone 24 14.0 1412 4 Gran Urea 100 215 Amazone 24 13.8 140 6 Prilled Urea 100 215 Amazone 24 27.9 197 7 Prilled Urea 100 215 Amazone 24 23.4 195

10 Prilled AN 100 290 Amazone 24 16.6 159 11 Prilled AN 100 290 Amazone 24 13.6 166 12 Prilled AN 100 290 Amazone 24 16.8 156 13 Gran Urea 100 215 Bogballe 24 13.3 143 14 Gran Urea 100 215 Bogballe 24 14.2 150 15 Gran Urea 100 215 Bogballe 24 11.9 159 17 Prilled AN 100 290 Bogballe 24 14.6 212 18 Prilled AN 100 290 Bogballe 24 15.8 205 19 Prilled AN 100 290 Bogballe 24 14.6 195 24 Gran Urea 100 215 Vicon 12 13.8 163 25 Gran Urea 100 215 Vicon 12 16.6 162 26 Gran Urea 100 215 Vicon 12 21.9 167 27 Gran Urea 100 215 Vicon 12 22.7 157 20 Prilled AN 100 290 Vicon 12 11.7 309 22 Prilled AN 100 290 Vicon 12 12.3 288

Fig.. 4.15. Typical field distribution based on 25 cm wide trays from an Amazone twin-disc spreader

applying Gran Urea fertiliser at 100 kg N / ha with a 24 m bout; inset shows wind vector relative to tractor travel direction.

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52

Distance m

kg/h

a values

wheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s


34

Fig. 4.16. Typical field distribution based on 25 cm wide trays from an Amazone twin-disc spreader

applying Prilled Urea fertiliser at 100 kg N / ha with a 24 m bout; inset shows wind vector relative to tractor travel direction.

Fig. 4.17. Typical field distribution based on 25 cm wide trays from an Amazone twin-disc spreader

applying Prilled AN fertiliser at 100 kg N / ha with a 24 m bout; inset shows wind vector relative to tractor travel direction.

0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52

Distance m

kg/h

a values

wheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52

Distance m

kg/h

a values

wheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s


35

Fig. 4.18. Typical field distribution based on 25 cm wide trays from a Bogballe twin-disc spreader

applying Gran Urea fertiliser at 100 kg N / ha with a 24 m bout; inset shows wind vector relative to tractor travel direction.

Fig. 4.19. Typical field distribution based on 25 cm wide trays from a Bogballe twin-disc spreader

applying Prilled AN fertiliser at 100 kg N / ha with a 24 m bout; inset shows wind vector relative to tractor travel direction.

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52

Distance m

kg/h

a values

wheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52

Distance m

kg/h

a values

wheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s


36

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Distance m

kg/h

a values

wheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s

Fig. 4.20. A field distribution based on 25 cm wide trays from a Vicon oscillating spout spreader

applying Gran Urea fertiliser at 100 kg N / ha with a 12 m bout; inset shows wind vector to tractor travel direction.

Fig. 4.21. Typical field distribution based on 25 cm wide trays from a Vicon oscillating spout spreader

applying Prilled AN fertiliser at 100 kg N / ha with a 12 m bout; inset shows wind vector to tractor travel direction.

0

50

100

150

200

250

300

350

400

450

500

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Distance m

kg/h

a

values

wheelingsC/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s


37

140.3 kg/ha CV 13.82 %

0

50

100

150

200

250

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Distance m

kg/h

a valueswheelings

C/L

Fig. 4.22. Typical field overlapped distribution pattern based on 25 cm wide trays from an Amazone

twin-disc spreader applying Gran Urea fertiliser at 100 kg N / ha with a 24 m bout; inset shows mean recovery and CV.

194.5 kg/ha CV 23.37 %

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Distance m

kg/h

a values

wheelings

C/L


twin-disc spreader applying Prilled Urea fertiliser at 100 kg N / ha with a 24 m bout; inset shows mean recovery and CV.


38

156 kg/ha CV 16.83 %

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Distance m

kg/h

a valueswheelings

C/L


twin-disc spreader applying Prilled AN fertiliser at 100 kg N / ha with a 24 m bout; inset shows mean recovery and CV.

158.7 kg/ha CV 11.89 %

0

50

100

150

200

250

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Distance m

kg/h

a values

wheelings

C/L

Fig. 4.25. Typical field overlapped distribution pattern based on 25 cm wide trays from a Bogballe twin-

disc spreader applying Gran Urea fertiliser at 100 kg N / ha with a 24 m bout; inset shows mean recovery and CV.


39

194.8 kg/ha CV 14.59 %

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Distance m

kg/h

a valueswheelings

C/L

Fig. 4.26. Typical field overlapped distribution pattern based on 25 cm wide trays from a Bogballe twin-

disc spreader applying Prilled AN fertiliser at 100 kg N / ha with a 24 m bout; inset shows mean recovery and CV.

163.2 kg/ha CV 13.83 %

0

50

100

150

200

250

0 2 4 6 8 10 12 14 16 18 20 22 24

Distance m

kg/h

a valueswheelings

C/L

Fig. 4.27. A field overlapped distribution pattern based on 25 cm wide trays from a Vicon oscillating

spout spreader applying Gran Urea fertiliser at 100 kg N / ha with a 12 m bout; inset shows mean recovery and CV


40

288.1 kg/ha CV 12.25 %

0

50

100

150

200

250

300

350

400

450

0 2 4 6 8 10 12 14 16 18 20 22 24

Distance m

kg/h

a valueswheelings

C/L

Fig. 4.28. Typical field overlapped distribution pattern based on 25 cm wide trays from a Vicon

oscillating spout spreader applying Prilled AN fertiliser at 100 kg N / ha with a 12 m bout; inset shows mean recovery and CV

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Distance m

kg/h

a valueswheelings

C/L

-4

-3

-2

-1

0

1

2

3

4

-4 -3 -2 -1 0 1 2 3 4

m/s

m/s

Fig. 4.29. A field distribution based on 25 cm wide trays from a Vicon oscillating spout spreader

applying Gran Urea fertiliser at 100 kg N / ha with a 12 m bout; inset shows wind vector to tractor travel direction.


41

157.3 kg/ha CV 22.71 %

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14 16 18 20 22 24

Distance m

kg/h

a values

w heelings

C/L

Fig. 4.28. A field overlapped distribution pattern based on 25 cm wide trays from a Vicon oscillating

spout spreader applying Gran Urea fertiliser at 100 kg N / ha with a 12 m bout; inset shows mean recovery and CV

Further field tests were carried out at Silsoe Research Institute in October 2004. The aim of the tests, as described in Section 3.10, was to investigate compare the sensitivity of optimised applications of Gran Urea and Prilled AN to meteorological conditions and field effects. The measurements were made from a single 24 m bout within an area, during up and down field application. The results are summarised in Table 4.4. Further details of the measurements, including meteorological conditions, are given in Appendix 10.11. Two applications were made, each were sampled with two transects using a 24 m wide layout of sampling trays. Both applications were made in a light crosswind but conditions were humid with RH exceeding 80%. With both applications measured distributions were uneven with high CVs. The poor results could be a result of the high humidity or perhaps an undiscovered machine setting problem. Nevertheless, whatever the reason, the Gran Urea results were better than for the benchmark Prilled AN application. It was because it was this difficult to explain the poor result that it was decided to carry the further laboratory tests with the FMA rig to establish how humidity influences distribution as measured in the laboratory. Table 4.5 Summary results of area distribution measurements from twin-disc spreaders with Urea and

AN fertilisers (October 2004).

Run Product Target Rate Machine CV Recovery

# N kg/ha kg/ha % kg/ha 1A Prilled AN 100 292 Amazone 58.6 93 1B Prilled AN 100 292 Amazone 59.2 94 2A Gran Urea 100 215 Amazone 41.3 128 2B Gran Urea 100 215 Amazone 37.5 121


42

5. Theoretical considerations

5.1 Predicting spreading performance from particle size and density It was clear from Section 4, particularly in the results from the indoor hall tests, that there was a strong relationship between fertiliser distribution width and particle size & density. In particular there appeared to be a clear relationship between particle mass and the 10% to 90% treatment width. To establish this on a firm basis that would enable overall performance to be predicted, a series of calculations was made using basic particle physics and the results compared with the indoor hall tests. It is common in aerosol physics to define a length scale parameter that defines the dynamics of a particle in an air flow (Davies 1966). This parameter, stop distance, is defined as the distance taken for a particle projected at an initial velocity in still air to decay to 1/e of its original velocity. It is equivalent to a half-life velocity and is directly related to the particle relaxation time. For aerosols that obey Stokes Law stop distance can be directly calculated from the physical properties of the particle and the media. Stop distance is useful to parameterise the behaviour of particles when they are projected or when they are separated in a diverting airflow. It is widely used in air filtration and aerosol sampling. Because the projection of fertilisers is essentially an aerodynamic process, the use of a stop distance to parameterise the spreading behaviour of fertiliser of differing sizes and densities was investigated. Although there are several formulae that can be used to calculate a particle stop distance a useful simple formulation is

gVV

S T0= (5.1)

where S is stop distance, V0 the initial projection velocity, VT the terminal velocity of the particle and g acceleration due to gravity. V0 can be regarded as a machine property and VT a particle property. It can be seen from above that larger particles with greater terminal velocities have larger stop distances and machines with greater projection velocity spread further. In order to determine S for fertiliser particles it is necessary to determine VT . Particles move at terminal velocity when their weight balances the drag force FD. Thus

Dap F = gd )(6

3

ρρπ

−⎟⎟⎠

⎞⎜⎜⎝

⎛ (5.2)

where d is the diameter of the particle, ρp is the density of the particle and ρa is the density of air. The drag FD on spherical particle moving through air can be described by

⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛2V

4dC = F

2a

2

DDρπ (5.3)

where CD is the particle drag coefficient, and V relative velocity between the particle and air. The particle drag coefficient is a function of the particle Reynolds (Re) number for the flow which is calculated from


43

a

a dVη

ρ=Re (5.4)

where ηa is the viscosity of air. The relationship between the drag coefficient CD and Re is not simple. For small particles moving slowly where Re is low, analytical solutions such as Stokes Law exist and larger particles moving at high velocity obey Newton’s Law where CD ≈ 0.44. Between Re = 1 and 1000 there is a transition region where it is particularly difficult to determine CD accurately with a simple equation. This is shown on Fig. 5.1.

Fig. 5.1 Drag coefficient for spherical particles as a function of Reynolds number To provide a method of calculating drag force over the whole range of particle sizes used in fertiliser application the calculation scheme described in Douglas et al (1995) was used.

2.0for24<= Re

ReCD (5.5)

5002.0for5.18<<= Re

ReC 0.6D (5.6)

500for44.0 >= ReCD (5.7)

Using an Excel spreadsheet and the Solver Add-In optimisation procedure, the terminal velocity of urea and ammonium nitrate particles of various sizes were calculated using equations 5.2 – 5.7. From the calculated values for VT the stop distances (S) of particles projected with a 20 m/s initial velocity (V0) were using equation 5.1. This initial velocity was considered as being a typical for twin disc fertiliser spreaders. Fig. 5.2 shows the results for both urea and ammonium nitrate using standard density values for each product. In Table 5.1 the stop distances for the median particle sizes used in the indoor distribution tests are shown. It can be seen that the change 30% reduction in density from ammonium nitrate to urea gives a 14 % decrease in predicted stop distance. However, increasing the particle size from 2.2 mm to 3.2 mm increases the predicted stop distance by nearly 19%.


44

10

12

14

16

18

20

22

24

26

28

30

0 1 2 3 4 5 6

Particle diameter mm

Stop

dis

tanc

e m

ANUrea

Fig. 5.2. Calculated stop distance of spherical particles of ammonium nitrate and urea projected at an

initial velocity of 20 m/s Table 5.1. Calculated stop distance for particles with a 20 m/s initial velocity

Stop Distance m Particle size mm Product 2.2 % increase 3.1 % increase 3.8 AN 18.9 18.7 22.4 10.7 24.8 Urea 16.6 18.7 19.7 10.7 21.8 % decrease 13.85 - 13.85 - 13.85

The calculated stop distances are plotted on Fig. 5.3 against measured 10% to 90% treatment width. It is clear that there is strong relationship between treatment width and stop distance, particularly at low application rates where mass flow off the discs is also low. To investigate this first further the 40 kg N/ ha results were regressed against stop distance and shown to have linear fit with R2 = 0.935. Therefore, although detailed performance and distribution cannot be predicted from basic considerations such as particle size and density, it does appear that broad performance criteria can be predicted. For example, for a specified bout width and a spreader with known performance the particle size likely to be required to achieve that width for a product with a different particle density can be predicted. To investigate this further stop distances for a range of particle sizes and densities were calculated. These values are shown on Table 5.2.


45

Gran AN 3.1

Gran Urea 3.8

Gran Urea 3.1

Prilled AN 2.2

Gran AN 3.8

18

19

20

21

22

23

24

25

26

18 19 20 21 22 23 24 25 26

Stop distance m

90-1

0% tr

eatm

ent w

idth

m

100 kg N/ ha

70 kg N/ ha

40 kg N/ ha

Linear (40 kg N/ ha)

Fig. 5.3. 90-10 % treatment width from an Amazone twin-disc spreader based on 50 cm wide bins and

correlated with calculated stop distance based on 20 m/s projection velocity and median particle size. The trend line is based on the 40 kg N / ha data.

Table 5.2 Calculated stop distances using equations 5.2 – 5.7 for particles of various sizes and densities

projected at 20 m/s.

Particle density kg/ m3 Particle size

mm 1250 1375 1500 1625 1750 2000 2250 1.0 9.60 10.28 10.94 11.58 12.21 13.44 14.52 1.2 11.86 12.43 12.99 13.52 14.03 15.00 15.91 1.4 12.81 13.43 14.03 14.60 15.15 16.20 17.18 1.6 13.69 14.36 15.00 15.61 16.20 17.32 18.37 1.8 14.52 15.23 15.91 16.56 17.18 18.37 19.49 2.0 15.31 16.05 16.77 17.45 18.11 19.36 20.54 2.2 16.05 16.84 17.59 18.30 19.00 20.31 21.54 2.4 16.77 17.59 18.37 19.12 19.84 21.21 22.50 2.6 17.45 18.30 19.12 19.90 20.65 22.08 23.42 2.8 18.11 18.99 19.84 20.65 21.43 22.91 24.30 3.0 18.75 19.66 20.54 21.38 22.18 23.72 25.16 3.2 19.36 20.31 21.21 22.08 22.91 24.49 25.98 3.4 19.96 20.93 21.86 22.76 23.62 25.25 26.78 3.6 20.53 21.54 22.50 23.42 24.30 25.98 27.56 3.8 21.10 22.13 23.11 24.06 24.97 26.69 28.31 4.0 21.65 22.70 23.71 24.68 25.61 27.38 29.05 4.2 22.18 23.26 24.30 25.29 26.25 28.06 29.76 4.4 22.70 23.81 24.87 25.89 26.87 28.72 30.46 4.6 23.21 24.35 25.43 26.47 27.47 29.37 31.15 4.8 23.71 24.87 25.98 27.04 28.06 30.00 31.82 5.0 24.20 25.38 26.51 27.60 28.64 30.62 32.48


46

Although the information in Table 5.2 could form the basis of a calculation procedure based on an Excel look-up table and interpolation, a more simple method of using this data can be developed using a contour plot. This is illustrated in Fig. 5.4 where the data is presented as a contour plot of calculated stop distances plotted against particle size and density for 20 m/s projection velocity. To illustrate how the plot might be used to inform fertiliser product choices some example values are shown on the plot. If, for example, a spreader is set up to apply a material with a 1850 kg/m3 particle density and with a median particle size of 2.8 mm then the contour plot shows that the application has a stop distance of ≈ 22 m. If a lighter material with a particle density of 1500 kg/m3 is required to be spread through the same spreader then to achieve the same treatment width it is estimated that a particle size of ≈ 3.4 mm would be required. To obtain a similar spreading width from a Gran Urea application as Prilled AN application that had a particle size of 2.2 mm, from Fig. 5.4 a particle size of ~ 2.85 mm would be required. This probably explains why the Gran Urea 3.1 application performed well in both field and laboratory tests often out performing the Prilled AN application. A larger version of Fig. 5.4 is presented in Appendix 10.12

1 2 3 4 5Particle.size.mm

1250

1375

1500

1625

1750

1875

2000

2125

2250

Parti

cle.

Den

sity

.Kg.

..m3

12

13

14 15

16

17

18

19

20

21

22 23

24 25

26

27

28 29 30

Fig. 5.4 Contour plot of calculated stop distance against particle size and density with draft lines showing an example described in the text.

5.2 Modelling particle behaviour in the wind tunnel The results of tests on the winnowing behaviour of fertilisers showed the expected trends. The lighter but larger particle size Gran Urea 3.1 product appeared to have a similar downwind distribution to the heavier but smaller particle size Prilled AN 2.2. Using the calculated terminal velocity of the median particle size as an indicator of aerodynamic dispersion, Gran Urea 3.1 has a terminal velocity of 9.76 m/s and Prilled AN 2.2 a stop distance of 9.36 m/s. It would therefore be expected that in a wind tunnel the two products would have broadly similar behaviour but that the prilled urea might not disperse as far down the wind tunnel. As seen in Appendix 10.5


47

the cumulative and frequency distributions of both materials were very similar. However, the Prilled AN material with its narrower particle size range had a tighter downwind range. To investigate the influence of particle size and density further a particle trajectory model (Miller et al ) was used to calculate the down wind distribution of the various size fractions of the product and the weighted results used to provide a predicted down wind distribution for the complete product.

0

5

10

15

20

25

30

35

40

45

0.5 1 1.5 2 2.5 3

Distance downwind m

% M

ass

AN

Gran Urea

AN (Predicted)

Gran Urea (Predicted)

Fig. 5.4. Predicted and measured downwind frequency distributions of fertilisers released into an 11 m/s

wind in the SRI wind tunnel.

0

10

20

30

40

50

60

70

80

90

100

0.5 1 1.5 2 2.5 3

Distance downwind m

% M

ass

AN

Gran Urea

AN (Predicted)

Gran Urea (Predicted)

Fig. 5.5. Predicted and measured downwind cumulative distributions of fertilisers released into an 11

m/s wind in the SRI wind tunnel.


48

As can be seen from both Figs. 5.4 and 5.5 the predicted downwind deposition lies closer to the source than the measured. This is likely to be the result of particle bounce. High-speed video of particles being sampled by the honeycomb structure showed that although bounce was minimised by the structure it was not eliminated. Also it is clear from Fig. 5.5 that not all the fertiliser released into the air flow was captured. Material that bounced on impact with the collecting array was often observed travelling considerable distances down the tunnel. It should be pointed out that because both predicted and measured distributions are in similar relative positions and the shapes of the measured and predicted distributions are very similar, it appears that if particle bounce effects are ignored then ballistic theory is a good predictor of the behaviour of fertiliser particle released into a wind flow.


49

6. Key conclusions

1. Commercial samples of urea obtained in early 2004 showed that the quality of material available to the UK

market varied both by location and by supplier. There appeared to be no market “standard”. Those samples where the material was granulated and of larger particle size were considered to be of better quality and less likely to give a poor spreading performance. From the tests carried out during this project a good quality urea would be a product with a median particle size greater than 3 mm and with few fines. Several of the on-farm samples of granular urea obtained for this study, including the granular urea used in field and indoors tests, met these requirements. In 2004 it appears that there were no prilled products that met this requirement. WP1,2,3,5

2. Laboratory distribution tests showed that a good quality granular urea, as defined above, would achieve

results that could enable it to achieve the “SP5” quality rating currently used for ammonium nitrate products. WP 2

3. Measurements of the performance of twin disc fertiliser spreaders in a test hall and in the field using AN

showed that the machines achieved satisfactory uniformity at 24 m bout width with a prilled AN product and good performance with a granulated product that had a larger particle size. An oscillating spout spreader gave a good performance with AN at its targeted bout width of 12m. WP 3,4,5

4. Measurements of the performance of twin disc fertiliser spreaders in a test hall and the field using urea

showed that granulated products achieved satisfactory or good uniformity at 24 m bout width. The available prilled urea was of such poor quality in laboratory tests that it did not warrant field or hall testing. It was clear that it would not spread satisfactorily. An oscillating spout spreader gave a good performance with granulated urea at its targeted bout width of 12 m. WP 3,4,5

5. In experiments carried out during the project, granulated urea was shown to be no more sensitive to

increased humidity than ammonium nitrate. Limited field tests did not show any marked difference in the effect of wind on distribution of quality granular urea. WP 2,4

6. Manipulation of bulk samples by sieving enabled the effect of particle size to be studied in the hall tests.

The results showed that particle size has a significant effect on spreading width. There was a strong correlation between spreading width and particle stop distance (a parameter developed from basic trajectory theory) and this was confirmed by wind tunnel dispersion tests. WP 3,5

7. A contour plot of spreading width against particle size and density can predict the basic requirements for

solid fertiliser products that could achieve satisfactory performance with existing spreaders at 24 m and 12 m bout width. WP 6,7

8. This study has shown that correctly prepared, calibrated and operated twin disc spreaders can achieve a

satisfactory application of a quality granulated urea at 24 m bout width without the need for further machine improvements. Similarly, oscillating spout spreaders are suitable for use with quality granular urea at 12 m bout width. It would be unwise to make judgements on poorly set–up machines since they were not tested in this study. There is the potential for good quality granulated urea to be spread at bout widths greater than 24 m but this based on extrapolation and has not been tested. WP 3,4,5,6,7


50

7. Future research requirements

7.1 Evaluation of methods by which the application of urea can be improved. Discussion point: Work to date within NT2610 has shown that correctly prepared, calibrated and operated twin disc spreaders can achieve a satisfactory application at 24 m bout width when spreading granular urea. An oscillating spout machine can also operate successfully at 12m with granular urea. Question: Although the tests involved in this project have been carried out under as realistic scenarios as possible, because not all situations may be as favourable as those used, is there a need for policy of continuous improvement in fertiliser application? If the Answer is Yes then the following may be worthy of consideration. PRODUCT

• Examine the specification of urea and production quality issues • Investigate urea shelf life and storage issues e.g. bag sizes, storage conditions, bulk handling etc. • Investigate hygroscopic control to urea products; allowing both storage improvements and possible

spreading improvements. • Investigate the limitations that should be applied to prilled urea products – particle size etc.

SPREADERS

• Investigate flow conditions through hopper feed gates • Consider particle stop distance improvement in various wind speeds • Improve low application rate flow to discs e.g. at 70 and 40 kg N/ha

OPERATORS

• Carry out technology transfer to convince operators and owners of performance potential from current equipment – considerable resistance in field due to previous experiences with ‘poor quality’ ureas, particularly prills.

• Promote sound fertiliser stock management to avoid lumps and bridging in spreading routines. • Promote urea performance to in field spreader testing companies

LIQUID APPLICATION Field sprayers currently apply liquid fertilisers, some being home-mixed urea formulations. It is generally accepted that sprayers have lower CV in application, probably below 5%, compared to most fertiliser spreaders where ‘good’ levels of CV are 10% and below. This may need verification from available existing work. Whilst tramline (i.e. bout) widths are at 24 m, and solid fertiliser applications are made at that width or below, then applications are satisfactory and there is little need to move towards liquid application. However, the


51

reported move to wider tramlines from the latest sprayer survey (WD Basford Personal Communication 2005 ) shows a 200% increase in the arable area treated by booms above 24m in the last 3 years, although this was only 6% in 2004. Difficulties in applying solid product above 24m bout width could also promote the home-mixing of liquid product. Storage issues, shelf life of products, tank locations, quantity needed, and local infrastructure for delivery may all pose short term problems if there is a significant move towards liquid applications. Difficulties in application could also promote the home-mixing of product.


52

8. Acknowledgements

We would like to acknowledge the invaluable assistance with the indoor hall tests provided by Krister Persson and Hans Skovsgaard of DIAS, Bygholm. We would also like to thank Dave Baker (SRI) for his assistance throughout the project. Ian Muir (ADAS), Trevor Brocklesby (Amazone), Steve Watson (SRI), Roger Sharpe (SRI), Andy Lane (SRI) and John Power (SRI) all provided assistance with the field experiments. We are also indebted to KRM Ltd and F.B. Parrish & Sons for providing the spreaders used in the field experiments. Clive Tuck (SRI) wrote the Visual Basic code that enabled us to analyse fertiliser distribution patterns and the SRI Analytical Laboratory were responsible for the analysis of the fertiliser samples. Peter Dampney (ADAS) helped source many of the fertiliser samples and the bulk materials tested.


53

9. References

Central Science Laboratory (2002) “A study of current farm sprayer practices in the United Kingdom” http://www.csl.gov.uk/science/organ/pvm/puskm/cpa-finalpublication.pdf

Dampney P.; Basford W.D; Goodlass G; Miller P.C.H.; Richards I. (2003) “Production and use of nitrogen fertilisers” Defra Report, NT2601 Project

Davies, C.N. (1966) “Deposition from moving aerosols” chapter in Aerosol Science, edit. CN Davies, Academic Press, London 468 pages

Douglas, J.F.; Gasiorek, J.M.; Swaffield, J.A. (1995) Fluid Mechanics, Longmon Group, Harlow, 3rd Edition 819 pages

England, R.A.; Audsley, E. (1987) “On the use of coefficient of variation as a measure of fertiliser distributor performance” Divisional Note DN 1385, AFRC Institute of Engineering Research, Silsoe, Bedford

Miller, P. C. H.; Hadfield, D. J. (1989) “A simulation of spray drift from hydraulic nozzles.” J. Agric. Engng. Res. 42, 135-147

Miller, P.C.H. (1996) “ The measurement & classification of the flow and spreading characteristics of individual fertilisers”, Proceedings, No. 390, International Fertiliser Society

Miller, P.C.H.; Parkin, C.S. (2005) “Procedures for classifying the physical quality of fertilisers” Paper presented at International Fertiliser Society meeting April 14, 2005, Geological Society, London

Persson, K. (1996) “Interactions between fertilisers and spreaders” Proceedings 389, International Fertiliser Society

http://www.csl.gov.uk/science/organ/pvm/puskm/cpa-finalpublication.pdf


54

10. Appendices

10.1 Work Packages

Work package WP1. Identify and source fertilisers for the study Lead organisation: ADAS Other contributors: None 1.1 To discreetly obtain 5 kg samples of product from manufacturing plants worldwide that may supply

fertiliser to the UK Information from previous studies will be used to identify potential sources of urea-based fertiliser that are

commercially available on the UK market. Representative 5 kg samples of material will be obtained for the initial laboratory measurements of physical characteristics (Work package WP2.1). It is estimated that between 30 and 40 samples of material from different sources will be obtained. Having assessed the 5 kg samples, larger 25 kg samples will be obtained from selected manufacturing plants for use in the SRI laboratory rig tests (WP2), to determine spreading characteristics and aerodynamic properties of the material particles. Measurements of the transverse distribution patterns in both test hall (WP3 and WP5) and field conditions (WP4) will require larger 2 tonne samples; a minimum of five such samples will be obtained. It will not be possible to define the sources from which larger samples are required until after some of the work in WP2 has been completed. Reference samples of 2 tonnes of two ammonium nitrate fertilisers will also be needed.

There is a need to ensure that urea fertilisers can be produced and supplied to an agreed specification.

Obtaining a minimum of three samples from three sources over a three month period will provide an estimate of the likely variability in supply of such materials.

1.2 To produce grades of granular urea from one manufacturing source but with different particle size

characteristics The aim is to produce urea grades from a single manufacturing plant with a constant production process

and chemical formulation (e.g. coatings), but with a range of mean particle sizes; this would enable the effect of particle size to be studied experimentally without complex interactions due to differences in other physical characteristics. At least five grades will be required. The urea grades will be obtained either by adjustments to the granulation process at a small batch granulation facility, or by sieving a selected urea product to produce the required grades which would have different mean particle sizes. If particles behave independently, then testing of a sieved product will aid the modelling of how urea with a known particle size distribution would behave.

Work package WP2. Assess the range of physical properties for all sourced materials and identify

candidate materials for further study Lead organisation: Silsoe Research Institute Other contributors: None 2.1 Measurement of physical characteristics


55

Laboratory measurements of the following physical properties of all the sourced materials, including references will be made:

• particle size distributions - using sieve tests to BS EN 1235:1995 • bulk density - to BS EN 1236:1995 • flowability - using agreed industry protocols • angle of repose • particle density

2.2 Laboratory measurements of spreading characteristics For selected samples used in 2.1 above, measurements of the likely spreading characteristics will be made

using laboratory techniques developed at Silsoe Research Institute in conjunction with the Fertiliser Manufacturers Association (now part of AIC). A laboratory rig in which material is fed from a vibrated hopper, through a calibrated orifice that also incorporates an agitator system and a mass flow rate sensor onto an idealised disc provides information relating to the flow characteristics on a spreading disc and the risk of particle shatter. Information from such rig studies has been used as the basis of determining compliance with spreading quality standards (the "SP5" scheme) operated by Silsoe Research Institute in conjunction with the Fertiliser Manufacturers Association and Lloyds Quality Assurance. Results from such rig tests will therefore provide a direct indication of the spreading characteristics of the urea-based materials to be tested. Techniques are also being developed for assessing the aerodynamic characteristics of fertiliser particles using wind tunnel tests in which the downstream deflections of particles introduced into a defined air flow condition are measured. Results from such measurements will be used in conjunction with data from the full-scale rig tests to define the relative spreading performance of the different urea-based materials when compared with reference materials based on ammonium nitrate.

2.3 Select materials for full-scale distribution pattern assessments in field and wind tunnel conditions The results from the measurements of the physical properties of the complete range of urea-based

fertilisers together with the laboratory rig assessments of spreading performance of the different materials will be used to select candidate materials for the full-scale testing in test hall and field conditions.

Work package WP3. Indoor (test hall) measurements of distribution patterns with different materials

and spreading mechanisms (e.g. disc, spout) Lead organisation: Silsoe Research Institute Other contributors:ADAS, Danish Institute of Agricultural Science (DIAS) A provisional booking of the large test hall facilities at the Danish Institute of Agricultural Science (DIAS)

has been made for a period during weeks 14-15, (29th March - 9th April 2004). This provisional booking will enable approximately 100 measurements of full-scale distribution patterns.

3.1 Define an experimental strategy

An analysis will be undertaken to define an approach to using the 100 initial measurement runs in the test hall to cover as wide a range of spreading variables as possible while maintaining statistical confidence in the results obtained. An analysis by England and Audsley (1987) showed that coefficient of variation (CV) was a useful measure to characterise the lapped distribution pattern from disc and spout type spreaders and that this statistic could be related to crop yield. However, many factors can lead to distributions with a high coefficient of variation value. In the proposed study, the main focus is to establish the parameters of the fertiliser material that could limit the width at which uniform spreading


56

could be achieved with existing application machinery. Methods of characterising and comparing distribution patterns will therefore be reviewed and a statistical framework defined for measurements in both test hall and field environments.

3.2 Make measurements in the test hall to a defined programme and with review of results obtained. Measurements will be made with at least two machines operating with two flow rates and at least six materials – including reference materials based on ammonium nitrate. Machines will be set as closely as possible to the optimum based on measurements of the physical properties of the material (see WP2 above) and a limited number of preliminary measurements. It is likely that the machines chosen will use spinning discs and therefore consideration will be given to making some measurements with an oscillating spout type machine. The test hall facility in Denmark incorporates an automatic system for collecting and weighing material in sampling trays. Data is delivered electronically to a system control room. This data will be reviewed at the end of each run and on completion of a series of runs and any changes necessary to the experimental framework will be made as necessary.

3.3 Collate and interpret results from the test hall measurements.

All of the data from the test hall measurements will be analysed and related to the results of measurements of physical material properties made in Work Package WP2. This analysis will use mathematical models of particle trajectories where appropriate and statistical techniques that already exist in the literature together with any new approaches defined from work in this project.

Work package WP4. Outdoor measurements of distribution patterns to determine the effects of weather and other “field” factors Lead organisation: Silsoe Research Institute Other contributors: ADAS For a sub-set of the machine/rate/material combinations used in Work Package WP3, a series of measurements of the distribution pattern obtained will be made in well monitored field conditions. The purpose of this part of the work is to ensure that the effects of field variables, particularly wind and angular movements of the spreading vehicle, are accounted for in the final analysis of the work.

4.1 Define experimental strategy and measurements to be made

Results from Work Packages WP2 and WP3 will be reviewed and a structure for the field measurements determined using similar approaches to those defined in 3.1 above.

4.2 Make distribution pattern measurements under field conditions A series of measurements will be made over a cut grass surface at Silsoe Research Institute. Machine

selection, rate settings and materials will have been defined from 4.1 above and measurements will be made using tray techniques as defined in ISO 5690/1. Tray weights will be monitored via a computer program such that results can be reviewed during the conduct of the experimental program.

Conditions during spreading will be monitored by using ultrasonic anemometers to measure wind speed

and sensors to monitor temperature and humidity over the complete period when a measurement is to be made.


57

4.3 Collate all experimental data, analyse and identify area for further study/clarification to be studied in Work Package WP5

All of the experimental data will be collated and analysed. Areas for further measurements will be defined and a strategy for the second series of test hall measurements to be made as part of Work Package WP5 will be defined.

Work package WP5. Indoor (test hall) measurements of spreading distribution patterns in defined

circumstances Lead organisation: Silsoe Research Institute Other contributors: ADAS, DIAS

This work will follow the same approaches as in Work Package WP3 and will aim to fill gaps and address questions posed by the results of Work Packages WP2, 3 and 4.

5.1 Conduct test hall experiments – interactive procedure reviewing results obtained

Following similar procedures to those outlined in Work Package WP3.

5.2 Analyse and collate results

As for Work Package WP3.

Work package WP6. Evaluation of methods by which the application of urea can be improved

Lead organisation: Silsoe Research Institute Other contributors: ADAS A desk study will be conducted to consider changes to urea application methods needed to achieve accurate spread patterns, for example reducing tramline spacings and applying in the form of a liquid. The work will use results from all of the experimental components of the project and simplified modelling approaches as appropriate.

Work package WP7. Collation, interpretation and reporting of results

Lead organisation: Silsoe Research Institute Other contributors: ADAS Results of all Work Packages will be used to define the spread characteristics of urea products with different physical properties, and to identify practical options for the use of solid urea fertilisers that would achieve spreading accuracies equivalent to those obtainable with ammonium nitrate. A model will be developed that will predict, as far as possible, the spread characteristics of a granular urea fertiliser product based on its physical properties.


58

10.2 Project management

The overall project management was carried by SRI (Prof. Paul Miller and Dr Steve Parkin); Bill Basford lead the ADAS input to the work. The Project Leader ensured that QA procedures were agreed and set up, and protocols were prepared and agreed for relevant Work Packages. Regular project progress meetings were held at three monthly intervals.


59

10.3 Physical characteristics of candidate urea fertilisers

10.3.1 2003 Samples

Sample IDMean bulk density

kg m-3Median particle size

mm Production Method

NT2601 Gran Urea AA 729 1.96 Granulated

NT2601 Gran Urea BB 725 3.52 Granulated

NT2601 Gran Urea CC 735 3.41 Granulated

0

20

40

60

80

100

120

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Size mm

% re

tain

ed

-10

0

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60

Sample ID

Mean bulk density kg m-3

Median particle size mm Production Method

NT 2601 Gran Urea DD 738 2.33 Granulated

NT 2601 Gran Urea EE 741 3.11 Granulated

NT2601 Gran Urea FF 771 3.42 Granulated

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61

10.3.2 2004 samples2




AL 1 720 1.83 Prilled

AL 2 745 3.12 Granulated


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2 Because information on the source of on-farm samples can be unreliable the samples were coded by ADAS.


62







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63







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64





Al 11 757 2.14 Granulated


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65







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66

10.4 Physical characteristics of selected fertilisers



mmFlowability

kg s-1 Angle of Repose º

Prilled AN 986 2.33 10.0 25.12

Gran AN 3.1 1103 3.09

Gran AN 3.8 1213 3.78

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67



mmFlowability

kg s-1 Angle of Repose º

Gran Urea 3.1 747 3.13 5.5 32.69

Gran Urea 3.8 ??? 3.76

Prilled Urea 763 1.97 6.5 34.98

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68

10.5 Aerodynamic properties of prilled ammonium nitrate & granular urea fertilisers.

0

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1.5 2 2.5 3

Distance downwind m

% M

ass

Prilled ANGran Urea

Fig. 10.1 Downwind mass frequency distribution of Prilled AN and Gran Urea fertilisers Fig. 10.2 Downwind mass cumulative distribution of Prilled AN and Gran Urea fertilisers

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1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9

Distance downwind m

% M

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Prilled ANGran Urea


69

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Particle Size mm

% u

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1.6251.751.87522.125

Distance downwind

m

Fig. 10.3 Cumulative size distributions downwind of hopper for Prilled AN

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1.6251.751.87522.125

Distance downwind

m

Fig. 10.4 Cumulative size distributions downwind of hopper for Gran Urea


70

0.0

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1.5

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1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5

Distance downwind m

Med

ian

part

icle

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m

Prilled ANGran Urea

Fig. 10.5 Median particle size downwind of hopper for Prilled AN and Gran Urea


71

10.6 Distribution and flow properties of fertilisers selected for field tests Fig. 10.6 Flow characteristics of Prilled AN fertiliser with varying relative humidity Fig. 10.7 Flow characteristics of Gran Urea with varying relative humidity

0

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0.8

1

1.2

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time s

Flow

kg/

s

87%86%84%84%82%79%61%57%

Relative Humidity

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kg/

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91%89%82%79%77%77%75%75%61%59%

Relative Humidity


72

Fig. 10.8 Flow characteristics of Prilled Urea showing hopper bridging Fig. 10.9 Radial distribution of Prilled AN fertiliser with varying relative humidity; the error bars

indicate the acceptable distribution for the SP5 test.

0

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s Prilled Urea Run 1Prilled Urea Run 2

Relative Humidity 76%

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Bin #

% re

cove

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Reference87%86%86%84%84%79%61%57%

Relative Humidity


73

Fig. 10.10 Radial distribution of Gran Urea fertiliser with varying relative humidity; the error bars

indicate the acceptable distribution for the SP5 test. Fig. 10.11 Radial distribution of Prilled Urea fertiliser with varying relative humidity; the error bars

indicate the acceptable distribution for the SP5 test.

0

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Reference91%89%82%79%77%77%75%75%61%59%

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ReferencePrilled Urea Run1Prilled Urea Run2


74

10.7 Influence of netting placed over field sampling trays To determine the influence of using netting with sample trays, a series of measurements were made in the DIAS indoor test hall. This had the advantage of allowing fertiliser to be distributed under controlled conditions and over a flat site. Also, the measurements in trays could be referenced against the DIAS bin collectors. Because different machine distribution mechanisms eject particles with different trajectories, measurements were made with all the three machines that were to be used in the field. Applications were made using Gran Urea at 100 kg N/ ha with the sampling trays placed alongside the DIAS bins as shown in Fig. 3.9. Three runs were made with each spreader. A typical comparison of the deposition pattern measured by DIAS bins and the field trays is shown in Fig. 10.12. The results from both are based on 25 cm wide samples.

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-25 -20 -15 -10 -5 0 5 10 15 20 25

Distance m

kg/h

a DIASTrays

Fig. 10.12 Typical 25 cm sample width distribution pattern for an Amazone spreader applying Gran Urea

at 100 kg N/ ha measured using the DIAS bins and field trays. It can be seen from Fig. 10.12 that although the results from the field trays and DIAS bins show the same width of treatment, the DIAS bins with their greater depth collect more material, particularly in the central section of the distribution. A typical comparison using netting over the field trays is shown in Fig. 10.13. A much closer agreement between the distribution patterns is clearly seen. At first examination it would appear that, despite the practical difficulties and associated time delays that might result from using netting, the use of netting in field experiments is preferable. However, because the focus of this project is the uniformity of fertiliser distribution and not fertiliser recovery the results from the measurements were processed to indicate CV. The uniformity (CV) and recovery values for all three machines with trays and trays covered with netting are shown on Table 1.


75

0

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-25 -20 -15 -10 -5 0 5 10 15 20 25

Distance m

kg/h

a DIASTrays + Nets

Fig. 10.13 Typical 25 cm sample width distribution pattern for an Amazone spreader applying Gran Urea

at 100 kg N/ ha measured using the DIAS bins and field trays covered with netting. Table 10.1 Recovery and uniformity of Gran Urea fertiliser applied at 100 kg N /ha and collected in 25 cm

wide trays with and without covering netting.

Machine/ Bout

Sampling

Recovery kg/ha

CV % 25 cm

Trays 141.2 ± 1.5 12.0 ± 1.0 Amazone 24 m Trays & Netting 186.5 ± 2.2 11.3 ± 0.3

Trays 157.1 ± 0.6 11.5 ± 0.6 Bogballe 24 m Trays & Netting 195.5 ± 0.9 9.9 ± 0.8

Trays 196.7 ± 5.1 16.8 ± 0.9 Vicon 12 m Trays & Netting 217.2 ± 0.8 16.4 ± 0.9

It is clear from Table 10.1, that although netting improved the recovery of fertiliser for twin-disc spreaders operating at 24 m bout width (Amazone and Bogballe), it did not significantly alter the results of the measured distribution with the oscillating spout spreader operating at 12 m width (Vicon). However, the uniformity of distributions from the twin-disc spreaders was not significantly altered by the use of netting. A paired field comparison experiment using trays with and without netting was also carried out in August 2004 at Silsoe Research Institute using Prilled AN. A small decrease in CV was noted by the use of netting (12 % to 9.6 %) and a small increase in recovery (298 kg / ha to 356 kg / ha).


76

It was therefore concluded that although using netting in field experiments might improve sample recovery with some spreaders, because using netting over trays does not significantly alter uniformity then future field tests should be carried out without netting. Not using netting would have the advantage of increasing the turn-around time between measurements, increasing the number of measurements that could be taken in a day, thereby improving confidence in the results. Also, it should be noted that all field trials in this project were carried out as paired comparisons using urea and AN products under the same conditions with the same sampling system.


77

10.8 DIAS, Bygholm Tests March/April 2004 – AN fertilisers Run DIAS Code Product Machine CV Recovery

N kg/ha kg/ha % kg/ha73 2004040118 Gran AN 3.1 40 167 Amazone ZA-M maxIS 13.0 18374 2004040119 Gran AN 3.1 40 167 Amazone ZA-M maxIS 13.4 18175 2004040120 Gran AN 3.1 40 167 Amazone ZA-M maxIS 13.4 17776 2004040121 Gran AN 3.1 70 292 Amazone ZA-M maxIS 9.5 30077 2004040122 Gran AN 3.1 70 292 Amazone ZA-M maxIS 9.7 30278 2004040123 Gran AN 3.1 70 292 Amazone ZA-M maxIS 9.9 29770 2004040115 Gran AN 3.1 100 417 Amazone ZA-M maxIS 9.9 44071 2004040116 Gran AN 3.1 100 417 Amazone ZA-M maxIS 12.5 45772 2004040117 Gran AN 3.1 100 417 Amazone ZA-M maxIS 12.5 44164 2004040109 Gran AN 3.1 40 167 Bogballe Ex Trend 12.9 16965 2004040110 Gran AN 3.1 40 167 Bogballe Ex Trend 13.5 17066 2004040111 Gran AN 3.1 40 167 Bogballe Ex Trend 12.7 17161 2004040106 Gran AN 3.1 70 292 Bogballe Ex Trend 9.2 30062 2004040107 Gran AN 3.1 70 292 Bogballe Ex Trend 9.5 29363 2004040108 Gran AN 3.1 70 292 Bogballe Ex Trend 9.4 28858 2004040103 Gran AN 3.1 100 417 Bogballe Ex Trend 7.3 41359 2004040104 Gran AN 3.1 100 417 Bogballe Ex Trend 6.3 41460 2004040105 Gran AN 3.1 100 417 Bogballe Ex Trend 6.2 41384 2004040129 Gran AN 3.8 40 167 Amazone ZA-M maxIS 16.3 17385 2004040130 Gran AN 3.8 40 168 Amazone ZA-M maxIS 19.1 17286 2004040131 Gran AN 3.8 40 168 Amazone ZA-M maxIS 17.2 17189 2004040134 Gran AN 3.8 40 168 Amazone ZA-M maxIS 15.8 16890 2004040135 Gran AN 3.8 40 168 Amazone ZA-M maxIS 17.64 16391 2004040136 Gran AN 3.8 40 168 Amazone ZA-M maxIS 16.34 16779 2004040124 Gran AN 3.8 70 292 Amazone ZA-M maxIS 19.6 28480 2004040125 Gran AN 3.8 70 292 Amazone ZA-M maxIS 12.0 28481 2004040126 Gran AN 3.8 70 292 Amazone ZA-M maxIS 10.9 28787 2004040132 Gran AN 3.8 70 292 Amazone ZA-M maxIS 10.3 28382 2004040127 Gran AN 3.8 100 417 Amazone ZA-M maxIS 9.1 41883 2004040128 Gran AN 3.8 100 417 Amazone ZA-M maxIS 9.1 41888 2004040133 Gran AN 3.8 100 417 Amazone ZA-M maxIS 8.3 41714 2004033006 Prilled AN 2.2 40 116 Amazone ZA-M maxIS 15.5 12216 2004033008 Prilled AN 2.2 40 116 Amazone ZA-M maxIS 16.9 12517 2004033009 Prilled AN 2.2 40 116 Amazone ZA-M maxIS 16.8 12318 2004033010 Prilled AN 2.2 40 116 Amazone ZA-M maxIS 16.8 12511 2004033003 Prilled AN 2.2 70 203 Amazone ZA-M maxIS 9.2 20512 2004033004 Prilled AN 2.2 70 203 Amazone ZA-M maxIS 9.2 20713 2004033005 Prilled AN 2.2 70 203 Amazone ZA-M maxIS 10.5 2076 2004032906 Prilled AN 2.2 100 290 Amazone ZA-M maxIS 9.1 2907 2004032907 Prilled AN 2.2 100 290 Amazone ZA-M maxIS 9.2 3098 2004032908 Prilled AN 2.2 100 290 Amazone ZA-M maxIS 9.0 2899 2004033001 Prilled AN 2.2 100 290 Amazone ZA-M maxIS 9.7 29545 2020033110 Prilled AN 2.2 40 116 Bogballe Ex Trend 9.9 13146 2024033111 Prilled AN 2.2 40 116 Bogballe Ex Trend 11.5 13147 2028033112 Prilled AN 2.2 40 116 Bogballe Ex Trend 9.9 12743 2012033108 Prilled AN 2.2 70 203 Bogballe Ex Trend 9.6 22544 2016033109 Prilled AN 2.2 70 203 Bogballe Ex Trend 8.8 22848 2032033113 Prilled AN 2.2 70 116 Bogballe Ex Trend 8.6 22449 2036033114 Prilled AN 2.2 100 290 Bogballe Ex Trend 8.9 29750 2040033115 Prilled AN 2.2 100 290 Bogballe Ex Trend 8.6 29851 2044033116 Prilled AN 2.2 100 290 Bogballe Ex Trend 8.7 30329 2004033020 Prilled AN 2.2 40 116 Vicon Greenland Variospreader 8.9 12230 2004033021 Prilled AN 2.2 40 116 Vicon Greenland Variospreader 11.7 12031 2004033022 Prilled AN 2.2 40 116 Vicon Greenland Variospreader 10.7 12225 2004033016 Prilled AN 2.2 70 203 Vicon Greenland Variospreader 8.8 20626 2004033017 Prilled AN 2.2 70 203 Vicon Greenland Variospreader 8.3 19727 2004033018 Prilled AN 2.2 70 203 Vicon Greenland Variospreader 7.7 20421 2004033012 Prilled AN 2.2 100 290 Vicon Greenland Variospreader 7.0 29522 2004033013 Prilled AN 2.2 100 290 Vicon Greenland Variospreader 7.3 29523 2004033014 Prilled AN 2.2 100 290 Vicon Greenland Variospreader 7.9 29424 2004033015 Prilled AN 2.2 100 290 Vicon Greenland Variospreader 7.6 28453 2052033118 Lithuanian Prilled AN 100 290 Bogballe Ex Trend 10.1 29854 2056033119 Lithuanian Prilled AN 100 290 Bogballe Ex Trend 10.4 29355 2060033120 Lithuanian Prilled AN 100 290 Bogballe Ex Trend 10.1 29832 2004033023 Lithuanian Prilled AN 100 290 Vicon Greenland Variospreader 9.9 29833 2004033024 Lithuanian Prilled AN 100 290 Vicon Greenland Variospreader 9.4 28734 2004033025 Lithuanian Prilled AN 100 290 Vicon Greenland Variospreader 8.5 270

Data based on DIAS analysis 50 cm wide bins

Target Rate


78

10.9 DIAS, Bygholm Tests August 2004 – Urea fertilisers Run DIAS Code Product Machine CV Recovery

N kg/ha kg/ha % kg/ha12 2004080912 Gran Urea 3.1 40 87 Amazone ZA-M Max 11.9 9113 2004080913 Gran Urea 3.1 40 87 Amazone ZA-M Max 14.3 8816 2004081002 Gran Urea 3.1 40 87 Amazone ZA-M Max 13.1 8934 2004081020 Gran Urea 3.1 40 87 Amazone ZA-M Max 8.2 9235 2004081021 Gran Urea 3.1 40 87 Amazone ZA-M Max 10.4 8836 2004081022 Gran Urea 3.1 40 87 Amazone ZA-M Max 11.8 899 2004080909 Gran Urea 3.1 70 152 Amazone ZA-M Max 8.3 164

10 2004080910 Gran Urea 3.1 70 152 Amazone ZA-M Max 7.8 16411 2004080911 Gran Urea 3.1 70 152 Amazone ZA-M Max 7.6 16431 2004081017 Gran Urea 3.1 70 152 Amazone ZA-M Max 6.3 16532 2004081018 Gran Urea 3.1 70 152 Amazone ZA-M Max 7.9 16233 2004081019 Gran Urea 3.1 70 152 Amazone ZA-M Max 6.1 1612 2004080902 Gran Urea 3.1 100 217 Amazone ZA-M Max 9.8 2153 2004080903 Gran Urea 3.1 100 217 Amazone ZA-M Max 8.3 2064 2004080904 Gran Urea 3.1 100 217 Amazone ZA-M Max 7.2 2045 2004080905 Gran Urea 3.1 100 217 Amazone ZA-M Max 7.5 2116 2004080906 Gran Urea 3.1 100 217 Amazone ZA-M Max 5.7 2067 2004080907 Gran Urea 3.1 100 217 Amazone ZA-M Max 7.8 2048 2004080908 Gran Urea 3.1 100 217 Amazone ZA-M Max 9.5 204

79 2004081219 Gran Urea 3.1 40 87 Amazone ZA-M maxIS 11.4 9080 2004081220 Gran Urea 3.1 40 87 Amazone ZA-M maxIS 13.5 8481 2004081221 Gran Urea 3.1 40 87 Amazone ZA-M maxIS 14.3 8882 2004081222 Gran Urea 3.1 40 87 Amazone ZA-M maxIS 12.39 8871 2004081211 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 7.29 16472 2004081212 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 8.8 16873 2004081213 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 9.2 17574 2004081214 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 8.5 16976 2004081216 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 8.2 17277 2004081217 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 6.9 17278 2004081218 Gran Urea 3.1 70 152 Amazone ZA-M maxIS 5.0 17249 2004081107 Gran Urea 3.1 40 87 Bogballe Ex Trend 8.9 9050 2004081108 Gran Urea 3.1 40 87 Bogballe Ex Trend 9.6 9151 2004081109 Gran Urea 3.1 40 87 Bogballe Ex Trend 8.8 8946 2004081104 Gran Urea 3.1 70 152 Bogballe Ex Trend 6.7 15247 2004081105 Gran Urea 3.1 70 152 Bogballe Ex Trend 6.6 15748 2004081106 Gran Urea 3.1 70 152 Bogballe Ex Trend 6.8 15539 2004081025 Gran Urea 3.1 100 217 Bogballe Ex Trend 7.6 21840 2004081026 Gran Urea 3.1 100 217 Bogballe Ex Trend 6.8 22041 2004081027 Gran Urea 3.1 100 217 Bogballe Ex Trend 7.1 21342 2004081028 Gran Urea 3.1 100 217 Bogballe Ex Trend 5.8 21543 2004081101 Gran Urea 3.1 100 217 Bogballe Ex Trend 5.9 22144 2004081102 Gran Urea 3.1 100 217 Bogballe Ex Trend 7.5 21745 2004081103 Gran Urea 3.1 100 217 Bogballe Ex Trend 6.5 21766 2004081206 Gran Urea 3.1 40 87 Vicon Greenland Variospreader 11.6 8767 2004081207 Gran Urea 3.1 40 87 Vicon Greenland Variospreader 11.3 9068 2004081208 Gran Urea 3.1 40 87 Vicon Greenland Variospreader 10.1 8662 2004081202 Gran Urea 3.1 70 152 Vicon Greenland Variospreader 10.1 15063 2004081203 Gran Urea 3.1 70 152 Vicon Greenland Variospreader 11.1 15164 2004081204 Gran Urea 3.1 70 152 Vicon Greenland Variospreader 8.6 15052 2004081110 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 10.1 17754 2004081111 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 10.7 22055 2004081112 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 8.6 21156 2004081113 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 8.9 20757 2004081114 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 7.6 22358 2004081115 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 9.9 22159 2004081116 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 10.8 21860 2004081117 Gran Urea 3.1 100 217 Vicon Greenland Variospreader 10.5 21222 2004081008 Gran Urea 3.8 40 87 Amazone ZA-M Max 19.4 8123 2004081009 Gran Urea 3.8 40 87 Amazone ZA-M Max 18.3 8026 2004081012 Gran Urea 3.8 40 87 Amazone ZA-M Max 13.2 8327 2004081013 Gran Urea 3.8 40 87 Amazone ZA-M Max 12.1 7928 2004081014 Gran Urea 3.8 40 87 Amazone ZA-M Max 13.8 7720 2004081006 Gran Urea 3.8 70 152 Amazone ZA-M Max 16.2 15821 2004081007 Gran Urea 3.8 70 152 Amazone ZA-M Max 14.7 15825 2004081011 Gran Urea 3.8 70 152 Amazone ZA-M Max 10.3 16717 2004081003 Gran Urea 3.8 100 217 Amazone ZA-M Max 11.3 20118 2004081004 Gran Urea 3.8 100 217 Amazone ZA-M Max 11.7 20419 2004081005 Gran Urea 3.8 100 217 Amazone ZA-M Max 13.2 202

Data based on DIAS analysis 50 cm bins

Target Rate


79

10.10 SRI Field Tests August 2004 - Gran Urea and AN Fertilisers

Run Product Target Rate Machine CV Recovery# N kg/ha kg/ha % kg/ha3 Granulated urea 100 215 Amazone 14.0 1424 Granulated urea 100 215 Amazone 13.8 1406 Prilled Urea 100 215 Amazone 27.9 1977 Prilled Urea 100 215 Amazone 23.4 195

10 Nitraprill 100 290 Amazone 16.6 15911 Nitraprill 100 290 Amazone 13.6 16412 Nitraprill 100 290 Amazone 16.8 15613 Granulated urea 100 215 Bogballe 13.3 14314 Granulated urea 100 215 Bogballe 14.2 15015 Granulated urea 100 215 Bogballe 11.9 15917 Nitraprill 100 290 Bogballe 14.6 21218 Nitraprill 100 290 Bogballe 15.8 20519 Nitraprill 100 290 Bogballe 14.6 19520 Nitraprill 100 290 Vicon 11.7 30722 Nitraprill 100 290 Vicon 12.3 28824 Granulated urea 100 215 Vicon 13.8 16325 Granulated urea 100 215 Vicon 16.6 16226 Granulated urea 100 215 Vicon 21.9 16727 Granulated urea 100 215 Vicon 22.7 157


80

10.11 SRI Field Tests October 2004 - Gran Urea and AN Fertilisers

Run Product Target Rate Machine CV Recovery Wind Temp Humidity# N kg/ha kg/ha % kg/ha m/s ° C %

1A Nitraprill 100 292 Amazone 58.6 93 1.40 9.0 881B Nitraprill 100 292 Amazone 59.2 94 1.40 9.0 882A Granulated urea 100 215 Amazone 41.4 128 1.40 10.5 802B Granulated urea 100 215 Amazone 37.5 121 1.40 10.5 80


81

10.12 Contour plot of stop distance vs particle size and density for 20 m/s projection velocity

12

34

5P

artic

le.s

ize.

mm

1250

1375

1500

1625

1750

1875

2000

2125

2250

Particle.Density.Kg...m3

12 13

14

15 16

17

18 19

20

21 22

23

24 25

26

27

28

29 30

Documents

Spreading accuracy of solid urea fertilisers - Defra, UKrandd.defra.gov.uk/Document.aspx?Document=nt2610_6823_FRP.pdf · Spreading accuracy of solid urea fertilisers Report for Defra