Composting
Biodynamic composting
Biodynamic composting is a faster way of producing compost. Here the compost is made on the surface, rather than in the traditional pit. The heap is energised using a set of preparations that both enhance the nutrient content of the compost and hasten the decomposition process. The compost heap is built on a flat site away from tree shade and water logging. A rectangle around 2m wide and 4m long is marked out (the actual size depending on the biomass availability). A ‘wind tunnel’ of logs is placed lengthwise in the middle of the rectangle.
The rectangle is covered with a first layer of dry matter about 22cm thick which is then drenched and completely covered with cow dung slurry or goat manure. This is covered with a 15cm thick layer of green matter, which is sprinkled with water and covered with a thin layer of soil. The third layer again consists of 15cm of dry matter which is sprinkled with water and 30 kg of rock phosphate (which enhances decomposition and provides phosphorous). The fourth layer is again 15 cm of green matter which is sprinkled with water and covered with a layer of 30 kg crushed slaked lime (which also enhances decomposition). The fifth layer is more dry matter which is sprinkled with water and with cow dung slurry or goat manure. The sixth and final layer is 22 cm of green matter which is sprinkled with water and completely covered with cow dung or goat manure. The heap is plastered with a mixture of soil and cow dung (3:1) over the top and sides.
The final height of the compost heap is just over a metre. Any cracks in the plaster are immediately sealed with plastering slurry. Samples can be taken from 2-3 sides of the heap to check whether the compost is ready. The sample is crushed and smelt. A smell like forest soil indicates that degradation is 70-80% complete and the compost ready for use. Generally, compost is ready within 8-12 weeks (depending on the time of year).
Effective microorganisms (EM) technology and EM composting
'Effective microorganisms technology' is a method developed by Professor T. Higa of Japan in which a mixed culture of beneficial microorganisms (primarily photosynthetic and lactic acid bacteria, yeasts, actinomycetes, and fermenting fungi) is applied as an innoculant to increase the microbial diversity of soils. This improves the soil quality and health, which improves the growth, yield, and quality of crops. In the variant being tested at ICIMOD it is combined with composting, to make an easy to prepare and very effective organic fertiliser.
Composting is a largely biological process in which microorganisms (both aerobic and anaerobic) decompose organic matter and lower the carbon-nitrogen ratio of refuse resulting in a final product of well-rotted compost. Compost has a high content of organic matter and important nutrients and is very useful for soil conservation and improving and maintaining soil fertility. In cooler climates, however, and with coarse material, the process of composting can be quite slow.
The EM composting method uses effective microorganisms and molasses to speed up the composting process and provide an improved compost product. Vegetation, especially weeds from cropping alleys and unwanted (exotic) forest weeds like banmara (Euphatorium adenophorum), is chopped and mixed with a small amount of goat manure and fermented organic matter containing beneficial microorganisms, and 1% of a solution of EM in molasses. The mixture is placed in piles on the ground. In the summer, it transforms into mature compost in 5-6 weeks.
Pusa vermicomposting
Vermicomposting, or worm composting is a simple technology for converting biodegradable waste into organic manure with the help of earthworms (the red worm Eisenia foetida) with no pile turning, no smell, and fast production of compost. The earthworms are bred in a mix of cow dung, soil, and agricultural residues or pre-decomposed leaf-litter. The whole mass is converted into casts or vermicompost, which can be used on all types of plants in vegetable beds, landscaping areas, or lawns.
A 3m long, 1.25m wide, and 1m high pit is constructed with bricks on a moist and/or shaded site. If brick is not available, box or bamboo bin can also be used. To facilitate drainage digging into the soil, the base of the pit is covered with an 8 cm thick layer of sand. This is covered with a 15 cm thick layer of dry cow dung crushed into small pieces, followed by a layer of pre-decomposed degradable dry biomass and another thick layer of crushed dry cow dung. Finally the heap is covered with a thin layer of soil and the worms are poured on top.
A thatched roof should be built over the pit to maintain 40-50% moisture and 20-30°C temperature. Regular watering is needed to maintain the optimum moisture level. After 5-6 weeks, the top layer is removed and piled in one corner of the pit. After a few days, the newly exposed earthworms have burrowed down and the next top layer can be harvested. About 600 to 1000 worms can convert 45 kg of wet biomass in a week yielding about 25 kg of vermicompost. The earthworms are removed when all the compost has been taken out, and can be stored in moist paddy straw or a jute bag for later use. Vermicompost can be applied to any crop at any stage.
