Lecture -III

Compost and Composting

Compost Compost is a microbiologically well decomposed black to brown amorphous organo-mineral product

Composting:

Microbial Degradation Process that Converts Organic

Matter to a Stable Humus like Product under Controlled

Conditions.

More about food for your decomposers Your compost workers will thrive if you give them a

balanced diet.• Composting will be most rapid if the decomposers are

fed a mix of carbon rich and nitrogen rich materials.

• Carbon rich organic wastes are known as “browns” Leaves (30-80:1) ;Straw (40-100:1) ; Paper (150-200:1); Sawdust (100-500:1); Animal bedding mixed with manure (30-80:1)

• Nitrogen rich organic wastes are known as “greens” Vegetable scraps (12-20:1); Coffee grounds (20:1);

Grass clippings (12-25:1); Manure- Cow (20:1); Horse (25:1); Poultry (10:1), with litter (13-18:1)

The word compost is derived from the Latin word “COMPONERE” to mean put together

Basic principles underlying Composting

Composition of plant materials C:N ratio

Mechanism of decomposition process which are brought about by microbes.

Aerobic vs anaerobic

A knowledge of Metabolism of these micro organisms.

Waksman et al.1949

Types of compostingComposting may be divided into two categories by the nature of the decomposition process. In anaerobic composting, decomposition occurs where oxygen (O) is absent or in limited supply. Under this method, anaerobic micro-organisms dominate and develop intermediate compounds including methane, organic acids, hydrogen sulphide and other substances. In the absence of O, these compounds accumulate and are not metabolized further. Many of these compounds have strong odours and some present phytotoxicity. As anaerobic composting is a low-temperature process, it leaves weed seeds and pathogens intact. Moreover, the process usually takes longer than aerobic composting. These drawbacks often offset the merits of this process, viz. little work involved and fewer nutrients lost during the process.

Aerobic composting takes place in the presence of ample O. In this process, aerobic microorganisms break down organic matter and produce carbon dioxide (CO2), ammonia, water, heat and humus, the relatively stable organic end product. Although aerobic composting may produce intermediate compounds such as organic acids, aerobic micro-organisms decompose them further. The resultant compost, with its relatively unstable form of organic matter, has little risk of phytotoxicity. The heat generated accelerates the breakdown of proteins, fats and complex carbohydrates such as cellulose and hemi-cellulose. Hence, the processing time is shorter. Moreover, this process destroys many micro-organisms that are human or plant pathogens, as well as weed seeds, provided it undergoes sufficiently high temperature. Although more nutrients are lost from the materials by aerobic composting, it is considered more efficient and useful than anaerobic composting for agricultural production. Most of this publication focuses on aerobic composting.

Essential requirements for composting :-

A suitable starter

Addition of water

Presence of Air :

Massive organic Refuge

CEREAL STRWS, CROP STUBBLES, COTTON STALKS, GN HUSKS, SUGARCANE TRASH, FARM WEEDS AND GRASSES, HOUSE REFUSE, WOOD ASH, LIITER, URINE SOAKED EARTH FROM CATTLE SHED

URINE, DUNG, SEWAGE, SLUDGE, A/S, NaNO3, CaCN2

50-60% WATER for satisfactory decomposition

Oxidation process, requires O2, air to be introduced to the compost heap after 10-15 days

Points likely to remember for successful preparation of quality compost:

• Selection of suitable composting substrates- on the basis of C/N ratio and the content of recalcitrant material, alkaloids, phytotoxic materials, obnoxious substances, heavy metal and pesticides.

• Recipe of composting substrates- To have quality compost there should have definite blending ratio between the base raw materials and among other supportive substrates. Waste: raw cowdung:live soil :FYM, 8:1:0.5:0.5 is the right blending mixture(on dry weight basis) for quality compost preparation

• Methodology of composting- Composting methods like Heap, pit, windrow etc are used. But composting in heap produces good quality of compost heap produces good quality of compost and cost involvement is less.

• Use of compost culture- Carrier based composting culture (@0.05%) for expedite the rate of decomposition will help for quality compost

• Enrichment of composting- Compost is inheritantly low in plant nutrients. Fortification with biotic e.g. N-fixing and P-solubilizing organisms and organic farming acceptable naturally occurring low grade abiotic inputs like rockphosphate, pyrite etc can improve the nutrient status of the product. 20% rockphosphate, 5% pyrite and 0.05% each of nitrogen fixing bacteria and phosphate solubilizing m.o can improve the quality of compost wrt N and P.

Criteria for Composting

C : N ratio - 25-35 : 1

Particle size - 50 mm

Moisture content - 50-60%

Air flow - 0.6-1.8 m3/day/kg

Temperature - 550C - 600C

for 1st 3 days

Agitation - Periodic turning

at 15 days interval

Heap size - Any length,

1.5 m high, 2.5m wide

Activators - Microbial inoculants

Types of Composting

Indore Method (Rural compost) (Howard and Wad,1931)

Bangalore Method (Urban compost) (CN Acharya,1939)

Coimbatore Method

Anstead’s Method

ADCO Method (Hutchinson and Richards(1921)

NADEP method (N.D. Pandharipande )

NRL Method

Phosphocompost Method

Vermicompost method

EM (Effective microorganism ) Method

ADCO Process Agril. Development Company, England

Hutchinson and Richards(1921) at Rothamsted Experimental Station , England

ADCO powder as a starter material @ 7.0 kg/ 100 kg dry waste

Ammonium Sulphate : 60 lbsSuperphosphate : 30 lbsMuriate of potash : 25 lbsGround lime stone : 50 lbs

1 ton dry Compost

Procedure:The basic raw material straw is spread in layers and sprinkled over with a solution of ammonium sulphate. Then powdered lime stone is applied as broadcast. Then another straw layer is put on. The piling of the layer is continued till a decent heap of convenient height is built up. After about 3 months of fermentation the resulting material is similar to FYM and hence called “synthetic FYM”

MATERIALS Stalks of cotton, maize, millet and the pulses. (Ideally they should be chopped to a particle size below 2 inches). CONSTRUCTION

Start building the heaps by laying a lattice of old branches at the bottom. Divide the base area of the heap into a 6 (roughly equal) transverse sections, five of which are filled and one left vacant.

Indore Method Howard and Wad,(1931) Indian Institute of Plant Industry, Indore

Cowdung as starter and anaerobic processPrepare a trench having dimension; 30′x 14′ x 3′(Trench)

14ft

Make each section of 7 layers (figure 1) of 9″ thickness. In a 9″ layer, have 4″ of dry waste, 3″ of green weeds and leaves, 2″ of FYM and a sprinkling of urine-earth-wood ash.

(The layering process is illustrated in figure-2). 

Make 3 ventilation holes or vent of 4″ diameter. The first pole should be in the middle at a distance of not more than 7′ feet from the heap, the rest two vent will be in two corners with a maximum distance of 3½ft from each side. Continue building of the section up to a height of 5′, after establishing the air vents.Build five sections in the similar manner, leaving the sixth one vacant (The sixth one is utilized while turning the heap). Water the heap, lightly, just after completion and again in the next morning.

14f

Turning also facilitates thorough mixing of the ingredients and their aeration. Carry out 1st turnings after 2 weeks,followed by 2nd turning after 5 weeks. A third turning is realized only if the original materials are recognizable, after 9 weeks. It takes around 12 weeks for final composting, though a little longer during monsoons.

The final product has a pliable texture, an earthy smell and is dark brown or grey in colour. This matured compost is half of its original volume as it simply shrinks due to the cooling process.

4. Bangalore process [ Aerobic and anaerobic process] :

This process of composting was developed byDr.C.N.Acharya in the year 1949

1. Basic raw material used: Any organic material

2. Starters or inoculants[Undecomposed: FYM or mixture of dung and urine or Undecomposed] litter

3. Additives:Bone meal or oil cakes , wood ash

NADEP METHOD OF COMPOSTINGNarayan Deotao Pandharipande of Maharastra (Pusad).

DescriptionThis method of making compost involves the construction of a simple, rectangular brick tank with enough spaces maintained between the bricks for necessary aeration. The recommended size of the tank is 10’ (length) x 5’ (breadth) x 3’ (height). All the four walls of NADEP tank are provided with 6// vents by removing every alternate brick after the height of 1ft. from bottom for aeration. Tank can be constructed in mud mortar or cement mortar.

ESTABLISHMENT ACTIVITIES Raw materials required for filling NADEP tank: Agricultural waste (Dry & green) : 1350-1400 kg. Cattledung or biogas slurry : 98 –100 kg. fine sieved soil – 1675 kg. Water – 1350-1400 litre.

The important technique: the entire tank should be filled in one go, within 24 hours and should not go beyond 48 hours, as this would affect the quality of the compost.

Before filling, the tank is plastered by dilute cattle dung slurry to facilitate bacterial activity from all four sides. It is also filled in definite layers each layer consisting of the following sub layers.

4 to 6// thick layer of fine sticks, stems, (To facilitate aeration) followed by 4 to 6// layer of dry and green biomass.

4 kg Cow dung is mixed with 100 litre of water and sprinkled thoroughly on the agricultural waste to facilitate microbial activity.

60 kg of fine dry soil is spread uniformly over the soaked biomass for moisture retention and acts as a buffer during biodegradation

Thus the proportion of organic materials for each layer is 100 kg organic biomass: 4kg cowdung + 100 litre water+60 kg soil. In this way, approximately 10 -12 layers are filled in each tank. After filling the tank, biomass is covered with 3// thick layer of soil and sealed with cow dung + mud plaster

**** EM-based quick compostingEffective micro-organisms (EM) consist of common and food-grade aerobic and anaerobic micro-organisms: photosynthetic bacteria, lactobacillus, streptomyces, actinomycetes, yeast, etc. A unit consists of 9 pits measuring about 180 cm (length) × 120 cm (width) × 90 cm (depth), enclosed by low walls and covered with a roof

Preparation of EM solution (accelerator)One litre of 'instant solution' is made by Mixing 10 ml of EM10 ml of EM, 40 ml of molasses 40 ml of molasses and 950 ml of water 950 ml of water and leaving it for 5 to 7 days, depending on temperature. The solution is then added to 1 litre of molasses 1 litre of molasses and 98 litres of water to obtain 100 litres 98 litres of water to obtain 100 litres of ready-to-use EM solution. This amount is enough for 3 3 pits. The EM solution functioning as accelerator reduces the composting period from 3 months to 1 month.

EM-based quick composting in Myanmar

Raw materials for compost rice straw; farmyard manure; urea fertilizer; EM solution.

***Composting organic materials with high lignin content - coir pithCoir pith is a waste from the coir industry (TNAU, 1999). During the process of separating fibre from the coconut husk, a large volume of pith is collected. The pith, containing about 30% lignin and 26% cellulose, does not degrade rapidly, posing a major disposal problem. However, it can be composted by using the fungus Pleurotus sp. and urea.

To compost 1 tonne of coir pith, the materials required are: 5 spawn bottles (250 g) of Pleurotus sp. and 5 kg of urea

The first step in the compost preparation is to select an elevated shaded place, or to erect a thatched shed. The surface is then levelled and an area 500 cm × 300 cm is marked out. To start with, about 100 kg of coir pith is spread. About 50 g of Pleurotus spawn is spread over this layer. About 100 kg of coir pith is spread on that. On this layer, 1 kg of urea is spread uniformly. The process is repeated until all the pith (1 tonne) is utilized. Water is sprinkled repeatedly so as to maintain the moisture optimum of 50 %. Well-decomposed black compost is ready in about a month. The C:N ratio falls to about 24:1 and the N content rises from 0.26 to 1.06 percent.

*****Composting weeds:This method has been developed for composting weeds such as parthenium, water hyacinth (Eichornia crassipes), cyperus (Cyperus rotundus) and cynodon (Cynodon dactylon). The materials required are: 250 g of Trichoderma viride , Pleurotus sajor-caju consortia, and 5 kg of urea. An elevated shaded place is selected, or a thatched shed is erected.An area of 5 m × 1.5 m is marked out. The material to be composted is cut to 10-15 cm in size. About 100 kg of cut material is spread over the marked area. About 50 g of microbial consortia is sprinkled over this layer. About 100 kg of weeds are spread on this layer. 1kg of urea is sprinkled uniformly over the layer. This process is repeated until the level rises to 1 m. Water is sprinkled as necessary to maintain a moisture level of 50-60% . Thereafter, the surface of the heap is covered with a thin layer of soil. The pile requires a thorough turning on the twenty-first day. The compost is ready in about 40 days.

Windrow Composting

Bin composting

When is compost finished?

Compost is mature when• The color is dark brown• It is crumbly, loose,

and humus-like• It has an earthy smell• It contains no readily

recognizable feedstock• The pile has shrunk to

about 1/3 of its original

volume

Quality Judgment

Size Reduction of Heap

Colour of Product

C:N Ratio

Presence of Weed Seed

Presence of Pathogens

Seed Germination Test

Smell of Product

Crop Response

Benefits of Compost

Nutrient Value

Excellent Soil Conditioning Agent

Increases Organic Content

Improves Soil Texture

Improves Soil Permeability

Improves Water-Holding Capacity

Encourages Soil Microflora and Fauna

• Improved aggregation

Composting Microorganisms

Cellulose decomposers : Trichurus spiralis

Trichoderma viride etc.

Lignin decomposers : Polyporus versicolor

Ganoderma lucidum

Phanerochaete chryosporium etc.

Method of preparation of liquid manureMethod of preparation of liquid manure1.5 kg fresh cow dung and 1.5 kg fresh green leaves of Subalul and

Babla are to be taken in a closed mouth cotton bag. The bag is then placed inside 40 litres water taken in a drum. The drum is to be kept in a open place with covering the mouth for

about 20 days. The water is to be stirred every morning with a stick by removing the

cover over the drum and the whole task is to completed as quickly as possible.

After the required time period (there would be no bad odour and the colour of the liquid will change to light tea liquor) the concentrated liquid is then diluted with water 5 times (that means total volume of the liquid then come to 200 litres).

The diluted liquid is then applied either on soil surface or on the plant foliage.

Preparation of liquid manure

1.5 kg fresh cow dung + 1.5 kg fresh green leaves

40 litre of water

(after around 20 days)

Diluted and the final volume is 200 litreThe average nutrient content of the liquid manure: N – 1%, P2O5 – 2% , K2O – 2%.

Upon this handful of soil

Our Survival depends

Husband it & it will grow

Our food, fiber & fuel

& surround us with beauty,

Abuse it, the soil will degrade

& collaspe taking mankind with it

Concepts :

Organic wasteCrop rotation

Crop residueLegume

CompostBiol. Pest Management

Biofertilizer

Animal-based manure

Agro-industry waste

ORGANIC FARMING

Composting organic materials with high lignin content - lime treatment

By adding organic wastes such as sawdust, wood shavings, coir pith, pine needles, and dry fallen leaves, while preparing organic waste mixtures for composting, one can ensure that the compost produced contains sufficient and long-lasting humus. However, gardeners often find that where they use lignin-rich plant materials, the compost does not ripen rapidly.

A technique for making good compost from hard plant materials involves mixing lime in a ratio of 5 kg per 1 000 kg of waste material. Lime can be applied as dry powder or after mixing with a sufficient quantity of water. Treatment with lime enhances the process of decomposition of hard materials. Liming can enhance the humification process in plant residues by enhancing microbial population and activity and by weakening lignin structure. It also improves the humus quality by changing the ratio of humic to fulvic acids and decreases the amount of bitumen, which interferes with the decomposition process. Instead of lime, powdered phosphate rock Instead of lime, powdered phosphate rock can be used in a ratio of 20 kg per 1 000 kg of organic waste20 kg per 1 000 kg of organic waste. Phosphate rock contains a lot of lime. The phosphates and micronutrients contained in phosphate rock make composts rich in plant nutrients

Composting

Solid Composting Liquid composting

Solid Composting

Conventional Composting

Phospho-composting

Vermicomposting

Two-step composting

Method Oriented CompostingMethod Oriented Composting

Heap method

Pit Method

Vermicomposting

Substrate Oriented Composting

Agril Wastes

Industrial wastes

Municipal Solid Wastes (MSW)

Sewage Sludge

Enrichment /Enrichment / FortificationFortification

BioticBiotic AbioticAbioticOrganicOrganic

Procedure

A unit pile is about 5(l) ×1(w) ×1(h) m3 in size.

Straw is stacked in layers of 20 cm height, 1 m width, and 5 m length to form a pile. The pile is sprinkled with water (Plate 1) for adequate moisture content, followed by addition of a FYM layer 5 cm high, and the sprinkling of a few handfuls of urea (100-200 g). EM solution is sprinkled to accelerate aerobic decomposition.

1. Compost pile in preparation

2. The pile is covered with a plastic sheet after attaining the desired height

This procedure is repeated until the pile is about 1 m high and then it is covered with a plastic sheet (Plate 2).

The pile is turned after two weeks (Plate 3) and then again after another week. Normally, the compost is ready two weeks later when the heap has cooled down and the height of the pile has fallen to about 70 cm.

3.The pile is being turned

“The most problematic odour is ammonia NH3”

Grass clippings

Food scraps

Leaves

Using the natural process of decay to change organic wastes into a valuable humus-like material called compost

Compost

Kitchen scraps

Garden trimmings

Materials to avoid during composting

Avoid organic materials that could cause problems during or after composting

• Oil, fat, grease, meat, fish or dairy products, unwashed egg shells (tend to attract pests, vermin)

• Hard to kill weeds (bindweed, quackgrass) and weeds that have gone to seed (could infest garden area when compost is used).

Cat or dog waste attracts pests,

could spread disease)

Diseased or insect ridden plants

(could infect or attack garden plants when compost is used)

Practical example: Assume that a representative cultivated soil in a condition favouring

vigorous nitrification is examined. Nitrates are present in relatively large amounts and the C:N ratio is narrow. The general purpose decay organisms are at a low level of activity, as evidenced by low carbon-di-oxide production.

Now, suppose that the large quantities of organic residues with a wide C:N ratio (50:1) are incorporated in the soil under conditions supporting vigorous digestion. A change quickly occurs. The heterotrophic flora-bacteria, fungi, and actinomyctes - become active and multiply rapidly, yielding CO2 in large quantities. Under these conditions, nitrate nitrogen practically disappears from the soil because of the insistent microbial demand for this element to build their tissues. And for the time being, little or no N , is in a form available to higher plants. As decay occurs, the C/N ratio of the plant material decreases since C is being lost and N conserved.

This condition persists until the activities of the decay organisms gradually subside due to lack of easily oxidisable Carbon. Their number dercrease, CO2 formation drops off, N ceases to be at a premium and nitrification can proceed. Nitrates again appear in quantity and the original conditions again prevail except that, for the time being, the soil is somewhat richer both in nitrogen and humus.

This sequence of events, an important phase of the carbon cycle, is shown in Fig. (previous slide).