slow release fertilizer in crop production

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Use of Slow Release Chemical Fertilizers in Crop

Production

Speaker IRFAN

MOHAMMADM.Sc final(Ag.)

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Seminar inchargeDr. Rajhans Verma

CONTENTS

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Introduction

Why need slow release chemical fertilizers ?

Characteristics of slow release chemical fertilizers

Different Slow release chemical fertilizers Research findings

Conclusion

INTRODUCTION

The steady increase in population growth, food demand and the continuous reduction in cultivated land per capita induce steady intensification of fertilizer application worldwide.

Nitrogen use efficiency is generally <50% and phosphorus use efficiency 10-30% with application of urea, single super phosphate etc.

The conventional fertilizer losses dependents most of the processes that nutrients undergo in soil include transformations induced by microbes (N fixation, nitrification, denitrification, immobilization etc.), chemical processes (exchange, fixation, precipitation, hydrolysis, etc.) and physical processes (leaching, runoff, volatilization etc.).

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Cont..... The basic concept of slow release chemical fertilizers is that they

release their nutrient contents at more gradual rates that permit maximum uptake and utilization of the nutrient while minimizing losses due to leaching, volatilization or excessive growth.

Slow-release: The release rate of a nutrient from the fertilizers must be slower than that from a fertilizer in which the nutrient is readily available for plant uptake.

Nutrient management through use of slow release chemical fertilizers of macro and micro nutrients is viable tool in improving FUE of applied fertilizers through regulated supply/release of nutrients and synchronizes crop demand.

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Fig.-1. Decomposition model of the coating polymer of slow-release fertilizer

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Fig.- 2. Mode of action of a coated/encapsulated fertilizers (Basacote®) (Source: Hähndel, 1997, BASF).

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Why need slow release chemical fertilizers ?

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Reduced toxicity Reduce possible losses of nutrients- slower leaching

and run off, evaporation losses of ammonia. Decreases risk of environmental pollutionReduction in relevant gas emission.Slower release rate – plants are able to take up most of

the fertilizersReduce labour capital- less frequent application is

requiredLower salt index

Cont.....

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Characteristics of slow release chemical fertilizers

Slowly water soluble Low salt A single application should supply enough nutrient throughout the

entire growing season A maximum percentage recovery Not susceptible to environmental loss Lasts several weeks to several months Formulation allows fertilizer to slowly dissolve or release into the

soil solution surrounding roots Nutrient release is dependent on microbial decomposition or

physical and/or chemical processes in combination with microbial activity.

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Fig.- 3 The ‘ideal fertilizer’: the nutrient release is synchronized with the crop’s nutrient requirements (Source: Lammel, 2005).

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Slow release chemical fertilizers Slow release chemical fertilizers are available

in market viz:

Slow release N-fertilizersSlow release P-fertilizersSlow release K-fertilizersPolymer-coated multi-nutrient fertilizersSlow release micronutrient fertilizers

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Slow release N-fertilizers Organic-N low-solubility compounds. These can be further divided

into biologically decomposing compounds such as urea-formaldehyde, and chemically decomposing compounds, such as IBDU (Isobutylidene Diurea).

Fertilizers N product with a physical barrier that coated fertilizers. The fertilizer N coatings include organic polymer, resins, and inorganic materials like sulpher.

Inorganic low-solubility compounds. Fertilizers such as metal ammonium phosphates (e.g. magnesium ammonium phosphate and partially acidulated phosphate rock.

Nitrification and Urease inhibitor: Nitrapyrin.

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Fig.- 4. Water soluble, N low-solubility and N product with a coated.

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Organic-N Low-Solubility Compounds

It reduce the rate of N released to soil solution compared to urea or other inorganic N sources.

By slowly dissolving during the growing season. NO3

- will not exceed crop utilization rate, thereby reducing potential N losses predominately through leaching.

But reduced denitrification and volatilization losses are also possible.

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Table: 1. Common Organic-N Low-solubility Compounds

N-Source Base Compound Common Names N Content (%)

Inhibition Duration (Weeks)

Urea Formaldehyde

Ureaforms, Methylol urea, and Methylene urea

Nitamin, Nitroform, UF, Folocorn,

35-40 6-10

Isobutylidene Diurea

Isobutylidine urea IBDU 31 10-16

Triazone Triazone/ Urea N-Sure 28-33 6-10Melamine 2,4,6-triamino-

1,3,5-triazineNitrazine 50-60 6-12

Crotonylidene Diurea

Urea/ Crotonaldehyde

Crotodur, Triabon, CDU

34 6-12

16Source –Tisdle et al.(2014)

Fertilizers N product with a physical barrier that coated fertilizer

Coated Fertilizers- These are slightly soluble in soil solution, where the N release rate depends on microbial activity and hydrolysis.

These products are commonly used in turf, vegetable, and ornamental systems; however, they are increasingly used in cereal grain systems.

Polymer-coated fertilizers are the most recent technology for controlling N release and reducing N losses by leaching, denitrification, and volatilization.

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Cont…..

Only about 30% of granules are perfectly coated, whereas the coating of remaining granules is thin and/or cracked, which accelerates dissolution of the urea granule and N release.

If the S coating is too thick, then N release is slowed or "locked-off (no N release).

Therefore, the initial rapid N release could occur too early for recovery by the target plant, and a portion not released or released after the N is needed by the plant.

Coating degradation rate will increase with soil temperature and moisture.

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Fig.-5 Polymer- Sulfur-coated urea (PSCU)

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Table: 2 Common Coated Fertilizers N-Source Base

CompoundCommon Name N Content

(%)Inhibition Duration (Weeks)

Neem coated urea

Urea NCU, NICU (Nimin-coated urea

- -

Polymer- Sulfur-coated urea

Urea Polyplus,Poly-S

38-42 6-16

Sulfur-coated urea

Urea Enspan,SCU

30-42 4-12

Polymer-resin coated urea (PSCU)

Urea Polyon,Meister,Nutrisphere,Escote

38-44 8-14


Nitrification Inhibitors (NIs)

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Nitrification Inhibitors:- Adding NIs to fertilizer or manure reduces N03

- formation, maintaining more of the applied N as NH4+

, thus, reducing N leaching potential. A substance that inhibits the biological oxidation of ammoniacal-N to nitrate-N.

NIs also reduce potential denitrification of applied N by reducing the amount of N03

- available for denitrification.

Nitrapyrin and dicyandiamide are the most common NIs that reduce N losses when conditions are suitable for rapid nitrification to N03

-.

Table: 3 Common Nitrification Inhibitors

N-Source Base Compound Common Names

N Content (%)

N Process Inhibition Duration (Weeks)

Nitrapyrin 2-chloro-6-trichloromethyl pyridine

N-Serve,Stay-N 2000

- Nitrificationdenitrification

2-6

DCD dicyandiamide DCD,Ensan

1.6 - 4-8

DMPP 3,4-dimethypyrazole phosphate.

DMPP,Entec

12-26 - 6-8


Urease Inhibitors Urease Inhibitors: Inhibition of urea hydrolysis occurs by

reducing the enzymatic activity of urease, reducing the rate of urea conversion to NH4

+ . Nickel (Ni) is important for urease activity and new urease

inhibitor products may inhibit urease by adsorbing Ni on the CEC of the polymer coating the urea granule.

NBPT (n-butyl-thio phosphoric triamide) is the most common urease inhibitor and can be used with any N source or method of application.

These products are more effective in reducing N loss under conditions of high volatilization potential, especially where urea is surface applied in heavy residue environments.

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Table: 4 Common Urease Inhibitors

N-Source Base Compound

Common Names

N Content

(%)

N Process Inhibition Duration (Weeks)

Thiosulphate Ammonium or calcium

thiosulphate

ATSCaTS

12 Volatilization,

nitrification

2-3

NBPT n-butyl-thio phosphoric

triamide

Agrotain,SuperU

46 Volatilization

2-3


Slow Release Phosphorus Fertilizers P fertilizer through the use of polymer coatings may slow the

formation of these compounds increasing the supply of crop-available P.

It has long been understood that even under the best conditions only 20-30% of applied fertilizer P is taken up by the crop during the first cropping season.

It is also understood that at high soil pH levels, P is fixed by calcium (Ca) and magnesium (Mg) and at low soil pH levels predominately by iron (Fe) and aluminium (Al).

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Thus, the historical problem with the soil chemistry of residual P not taken up by the crop (70-80%).

It remaining on or near the soil surface has a possible environmental impact (Eutrophication) through the combined effects of soil erosion and higher P concentrations in run-off water and P fertilizers has been lack of availability

CONT……

Malefic Itaconic Copolymer (Avail®)

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Specialty fertilizer products has developed and high charge density dicarboxylic copolymers that affect the availability and plant utilization of applied P fertilizers.

These compounds are biodegradable and highly water-soluble.

The technology (Avail®) can be applied directly to granular P fertilizers as a coating or mixed into liquid fertilizers.

Malefic Itaconic Copolymer (Avail®) is reported to work by sequestering antagonistic ions that react with P in the soil solution.

Cont…..

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The high charge density of the additive adsorbs or “binds” the soil Ca and Mg, Fe and Al acting to reduce their availability for reaction product formation with applied fertilizer P forms, thus reducing precipitation and keeping the P in an available form for longer.

Slow Release Potassium Fertilizers Potassium is abundant in the earth’s surface.

90 % K in soils is in the fixed, 1-10 % non-exchangeable form.

Only 0.1-1 % is in the soil solution or on exchangeable sites.

In sandy soils, potassium is readily leached.

It can move rapidly out of the root zone and become unavailable to the plants.

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Cont….Slow-release potassium sources reduce the potential for

conversion to non-exchangeable forms and minimize the rate of leaching and fixation of the available potassium.

This can be achieved by using different types of coatings, like plaster of paris, wax etc on the potassium chloride or muriate of potash.

The polymer used is Polyacrylamide which is also useful in reducing soil erosion.

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Polymer-Coated Multi-nutrient Fertilizers Compared to the previous categories that only supply nitrogen,

PCRFs (Polymer-Coated Release Fertilizers) supply all 3 “fertilizer elements” (nitrogen [N], phosphorus [P], and potassium [K]), and many formulations include calcium, magnesium, sulphur, and micronutrients.

The defining characteristic of PCRFs, however, is the sophisticated polymer coatings that gradually release nutrients over extended periods.

Release rates can be as short as 3 months or as long as 18 months.

Nutrient release from PCRFs prills occurs by diffusion .

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Cont…

The process occurs in 2 stages. First, when prills are exposed to moisture in the soil or

growing medium, water vapour infiltrates into the prills and condenses on the soluble fertilizer salts, creating an increase in osmotic pressure.

Second, this elevated pressure within the prills causes the fertilizer ions to diffuse outward into the surrounding medium.

Some example:- Osmocote®, Multicote® and Nutricote® are available in many grade.

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Slow Release Micronutrient fertilizers

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Micronutrients are essential components of proteins and enzymes and are vital for increasing crop yields as well as improving the nutritional quality of food.

The bulk of micronutrients used all over the world today are water soluble salts that include mainly the sulphates or their chelated forms [Diethylene triamine penta acetic acid (DTPA), EDTA (Ethylene diamine tetra acetic acid) etc.].

Cont….

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The focus of research on slow-release fertilizers has been on the macronutrients (NPK).

Here slow-release functionality has been achieved by encapsulation of water soluble materials within a membrane or conversion to polymers of the urea aldehydes.

For micronutrients, the insoluble oxides and phosphate glasses and amino acids are also used .

A glassy phosphate produced by fusing oxides of micronutrients in phosphoric acid at 8000C.

Cont….

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Slow-release compositions are characterized by nutrient release mechanism that is based on either (i) diffusion through a membrane/coating or (ii) slow hydrolysis.

Metaphosphates and glassy phosphates dissolve by slow hydrolysis to release nutrient into the soil.

Nutrient release by diffusion or hydrolysis is dependent on soil parameters like water content, pH, ionic content, temperature

Cont….

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Insoluble compounds can be effective fertilizers only if rates of release of nutrient ions can match plant requirements throughout the growth period.

The slow-release fertilizer in this study has been developed with a different mechanism of nutrient release.

Here, plant roots are able to “digest” certain insoluble compounds by ion-exchange with the root hairs or by extracellular organic acid secretions that extract nutrients by chelation.

These compounds have low water solubility and high solubility in citrate and diethylene triamine penta acetic acid (DTPA).

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Research findings

Research findings

Table 5. Effect of Nutrisphere-N (NSN) addition to urea on ear leaf N and corn yield at Kansas

N Ratelb/A

Ear Leaf N % Corn Yieldbu/A

T1 : Control 1.78 139

T2 : 80 Urea 2.79 167

T3 : 80 Urea + NSN 2.90 184

T4 : 160 Urea 2.90 183

T5 : 160 Urea + NSN 3.07 216

T6 : 240 Urea 2.95 192

T7: 240 Urea + NSN 3.09 215

LSD(0.05) - 6

38Grant and Dowbenko (2005)Gordon, Kansas State Univ.

Canada Soil pH 7.0.

Treatment Grain yield

(kg ha-1)Straw yield

(kg ha-1)

N uptake

(kg ha-1)

Grain

N uptake

(kg ha-1)

Straw

P uptake(kg ha-1)

Grain

P uptake(kg ha-1)

Straw

F1 : ( UB ) 4768 5200 40.86 33.57 10.03 5.63

F2 : (RDF) 4427 4847 39.50 32.52 9.07 5.03

F3 : (UB+ 20% N) 4928 5514 49.21 41.43 11.16 6.31

CD at 5%223 338 3.7 3.53 0.75 0.44

39Chaudhari (2013)Clayey soilNAU, Navsari

Table 6: Grain, straw yield and N and P uptake in grain and straw as influenced by different treatments of fertilizers in rice.

Cont..

Cont…..Treatment Dose

F1: Apply N and P at 60 and 30 kg/ha in the form of pellet at

the time of planting at 8-10 cm deep in alternate row.

F2: Recommended practices (100:30:00 kg NPK ha -1) to apply

N in three split and P at the time of transplanting.

F3: Apply 60% RD of N and full dose of P in the form of

Pellets (Briquettes) at the time of planting at 8-10 cm deep

in alternate row in square + 20% N in the form of urea

broadcasting at panicle initiation stage.

40Chaudhari (2013)NAU, Navsari Clayey soil

Table 7: N and P content in grain and straw as influenced by different treatment of fertilizer in rice.

TreatmentN content

(%)

P content

(%)

Grain Straw Grain Straw

F1 : ( UB )0.85

0.64 0.21 0.11

F2 : (RDF) 0.890.67 0.20 0.10

F3 : (UB+ 20% N) 0.99 0.75 0.23 0.11

CD at 5% 0.052 0.039 0.013 0.006

41Chaudhari (2013)Clayey soilNAU, Navsari

Table 8. Pusa Neem Emulsion (PNE) as an ecofriendly coating agent for urea quality and efficiency in rice field

Treatments Grain yield of rice (t ha-1)

T1 :Uncoated urea @ 40 kg N ha-1 5.3

T2 :PNE coated @ 40 kg N ha-1 5.6





T7 :Control (0 N) 4.3

LSD (P=0.05) 0.59

42Prasad et al. (2001)IARI, Delhi Sandy clay-loam in texture

Table 9.Effect of different treatments on nutrient uptake by sugarcane ratoon

N P K N P K

T1 : Control(No fertilizer) 121.59 37.07 137.27 2.40 0.58 2.69

T2:100% NPK RD straight ferti. By conventional method

214.95 64.96 225.66 2.19 0.66 2.29

T3:100% NPK RD straight ferti. by crow bar (50:50)

306.76 60.72 339.99 3.21 0.63 3.54

T4 : 100% NPK RD briquette (50:50) 330.00 78.88 366.27 2.96 0.72 3.28

T5:75%NPK RD straight ferti by crow (50:50)

175.62 51.79 207.95 2.03 0.60 2.40

T6: 75% NPK RD briquette (50:50) 240.63 61.35 292.08 2.27 0.70 2.77

T7:50% NPK RD straight ferti by crow (50:50)

170.10 41.74 199.88 2.28 0.60 2.66

T8 : 50% NPK RD briquette (50:50) 181.24 45.48 237.81 2.20 0.66 2.88

CD at 5% 20.20 7.03 7.90

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Treatments Nutrient uptake(Kg ha-1)

Nutrient utilized by cane (Kg t-1)

More et al.(2014)CSRS, Padegaon Inceptisol

Table10: Effect of broadcast coated DAP Malefic Itaconic Copolymer (Avail®) on corn grain yield at Waseca, MN in 2002.

TreatmentsGrain yieldBu/A

Whole plant

source P ratelb P2O5/A

P management

Yield lb DM/ A

Uptakelb P/A

T1 : None 0 - 136.2 686 1.85

T2 : DAP 25 Broad cast 151.0 562 1.77

T3 : DAP 50 Broad cast 155.2 754 2.17

T4 : Coated DAP 25 Broad cast 171.8 778 2.72

T5 : Coated DAP 50 Broad cast 174.6 834 2.47

LSD (0.10) - - 18.6 134 NS

44Randall and Vetsch (2002)Waseca, MN Calcareous soils

Table 11. Maize response to enhanced P availability from

Malefic Itaconic Copolymer (Avail®)

Treatments Yield t/ha

T1 : Control, No P 8.16

T2 : MAP broadcast 8.28

T3 : MAP + Polymer broadcast 9.47

T4 : MAP banded 8.28

T5 : MAP + Polymer banded 9.85

LSD (0.05) 1.00

45Sanders et al. (2003) USA Acid soil pH 5.9. P2O5 @20 lb/A

Table 12: Polymer and P application methods effect on wheat yield

Treatments Yield t/ha

T1 : Control 3.14

T2 : MAP banded 3.68

T3 : MAP + polymer, banded 5.17

T4 : MAP broadcast 3.91

T5 : MAP + polymer, broadcast 4.41

T6 : MAP + seed, broadcast 3.70

T7 : MAP + polymer + seed, broadcast 4.59

LSD (0.05) 0.44

46Sanders et al. (2003)USA Soil pH 7.6. P2O5 @30 lb/A

Table 13: Corn responses to enhanced P availability on high soil pH (7.8).

Treatments Dry weight P g/6 plants

P % P Uptake mg/6 plants

Grain Yieldbu/A

T1 : Control, No P 14.5 0.306 44 108

T2 : MAP banded 18.8 0.309 58 116

T3 : MAP+polymer banded 19.3 0.328 64 122

LSD (0.10) 2.7 0.016 10 5

47Sanders et al. (2003)USA Soil pH 7.8. P2O5 @ 20 lb/A

Table 14 : Field trial using slow-release micronutrient fertilizers on rice yields, nutrient uptake, at Baruipur (variety- Jaya )

Treatments Yield(kg/ha)

Total Uptake (gm/ha)

Zn


Fe


Mn


Cu

Control 3242 70.6 246 140 21

S1- Sulphates 3076 70.6 350 158 22

S2- Sulphates 3596 75.6 303 162 26

S3- Sulphates 3748 85.7 341 179 23

P1- Slow-release 4647 105.1 472 236 33

P2- Slow-release 4998 120.8 615 288 33

P3- Slow-release 4383 110.6 492 229 34

CD (5%) 758.3 22.4 215 74.4 Cont ….

48Calcutta, WB Bandyopadhyay et al. (2014)New alluvium

Cont.... Multi micronutrient Slow-Release Fertilizer of Zinc, Iron, Manganese, and Copper

Treatments Level Dose

C Control; -S1 Sulphates of Zn, Fe, Mn,

and Cu;S1 : 1 kg/ha Zn + 0.33 kg/ha Fe + 0.165 kg/ha Mn + 0.083 kg/ha Cu;

S2 Sulphates of Zn, Fe, Mn, and Cu

S2 : 2 kg/ha Zn + 0.66 kg/ha Fe + 0.33 kg/ha Mn + 0.165 kg/ha Cu;

S3 Sulphates of Zn, Fe, Mn, and Cu

S3 : 4 kg/ha Zn + 1.33 kg/ha Fe + 0.66 kg/haMn + 0.33 kg/ha Cu.

P1 Slow-release micronutrients;

P1: 1 kg/ha Zn + 0.33 kg/ha Fe + 0.165 kg/ha Mn + 0.083 kg/ha Cu;


P2: 2 kg/ha Zn + 0.66 kg/ha Fe + 0.33 kg/ha Mn + 0.165 kg/ha Cu;


P3: 4 kg/ha Zn + 1.33 kg/ha Fe + 0.66 kg/haMn + 0.33 kg/ha Cu.

49Calcutta, WB Bandyopadhyay et al. (2014)

Table 15: Field trial using slow-release micronutrient fertilizers on potato yields, nutrient uptake, at Nalikul ( variety - Jyoti)

Treatments Yield(kg/ha)


Zn

Total Uptake

(gm/ha) Fe


Mn


Cu

Control 9900 217 764 69 91

S1- Sulphates 10700 239 948 107 97

S2- Sulphates 9500 216 915 93 97

S3- Sulphates 11000 277 756 85 103

P1- Slow-release 14075 432 1966 151 163

P2- Slow-release 12550 396 1756 140 148

P3- Slow-release 16025 560 2569 225 198

CD (5%) 3460.0 83.9 479.5 33.3 33.1

50Calcutta, WB Bandyopadhyay et al. (2014)Old alluvium

Table 16: Effect of different treatments on available nutrients by sugarcane ratoon at harvest

N P KInitial 289.00 27.00 310.00

T1 : Control(No fertilizer) 261.85 21.53 247.20

T2 : 100% NPK RD straight ferti. by conventional method 305.55 27.54 288.19

T3 : 100% NPK RD straight ferti. by crow bar (50:50) 316.65 37.68 302.32

T4 : 100% NPK RD briquette (50:50) 324.85 37.76 332.72

T5 : 75%NPK RD straight ferti by crow (50:50) 313.30 27.46 291.31


T7 : 50% NPK RD straight ferti by crow (50:50) 304.69 20.00 289.80


CD at 5% 13.62 9.69 27.63

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Treatments Available nutrient (Kg ha-1)

More et al.(2014)CSRS, Padegaon Inceptisol

Some disadvantages of SRFs

Most slow release chemical fertilizer cost considerably more to manufacture than conventional fertilizers.

Applying sulfur-coated urea almost always lowers soil pH as aforementioned. However, this acidification may cause nutrient disorders such as calcium deficiency or magnesium deficiency.

Nutrients are not released as predicted because of low temperatures, flooded or droughty soil, or poor activity of soil microbes.

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Application of slow release chemical fertilizers improves the yield, quality, nutrient uptake, nutrient availability and improve FUE as well as minimize nutrients losses in different crop.

Application of coated DAP and MAP helps in increase crop yield and enhancing P availability.

Application of Malefic Itaconic Copolymer MAP enhancing crop yield and P availability in calcareous soils.

The slow release chemical fertilizers technology of macro and micro nutrients not only has the potential to improve crop yields and farmer profits but also has positive implications on possible environmental footprint of fertilizer use.

Conclusion

Thank youFor your kind attention

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Education

slow release fertilizer in crop production