Vermiculture

Introduction

Vermiculture is a branch deals with rearing and maintaining of earthworms for vermicompost preparation. Earthworms decompose waste organic materials and given out in a granular form which is known as vermicompost. It also includes cocoons and young stages of earthworms. It includes different organic waste material like crop residues, straws, leaves, animal waste, residues of green manuring crops, household waste material etc.

Generally there are 3200 species of earthworms are occurring in nature. Out of these Eisenia fetida and Eudrelis eugina are used for preparing vermicomposed.

Two methods are used for vermicompose preparation.

• Heap method

• Trench method

Benefits of vermiculture

• The earthworms play a vital role in the entire process; in ploughing and fertilizing the soil and providing all the needed nutrition to the plants.
• The earthworms have contributed to improve the soil structure, soil fertility, promote soil aggregation, encourage favorable soil reactions and enrich the nutrient status of the soil and in the process promoting the plant growth and improving the quality of the produce.
• Earthworms churn the soil and make it porous.
• They improve the soil by helping it achieve proper air, water and solids in the required ratio for maximum plant growth.
• Earthworms improve the water infiltration rate. Its maze of tunnels increases the soil's ability to absorb water.
• Earthworms bring up minerals and make plant nutrients more available.
• Earthworms also neutralize soil pH. Analysis of earthworm castings or manure shows that the soil in the castings has neutral pH (7) regardless of whether the existing soil is above or below pH (7).
• Earthworms compost plant residues.
• Earthworms stimulate microbial population. Free-living nitrogen fixing bacteria are more numerous around the sides of the earthworm's burrows.

Steps to be followed for vermicompost preparation

• The basin of the tree itself can be used as a vermibed.
• Vermicastings at the rate of about 5-10 kgs. Should be applied per tree depending on the size and age of the tree.
• About 25 kgs. Of any farm yard manure (FYM) should be applied evenly on the top of the vermnicatings.
• This is then mulched with organic litter. Slashed weeds available on the farm can be used for this purpose.
• Watering can be done as per the regular applications itself, ensuring that proper moisture is maintained.
• When all the above steps are followed, a conducive atmosphere is created for triggering the vermicastings and starting the vermiculture process.
• Once the earthworms have the suitable environment for existence, they start consuming the organic matter and turning it into rich vermicompost.
• This vermicompost is a bio-fertilizer enriched with beneficial soil micro-organisms.
• The vermicastings are highly stable and do not disintegrate thus preventing soil erosion.
• The vermicompost contains all the essential plant nutrients like N, P and K, thus eliminate usage of any further chemical inputs.

Vermicomposting using paddy straw

Vermicomposting is an appropriate technique for efficient recycling of animal wastes, crop residues and agro-industrial wastes. Paddy straw is a wide C: N (80:1) organic material, low in nitrogen and phosphorus but fairly rich in potassium. In conventional method of composting, paddy straw takes 6-8 months for decomposition resulting in a poor quality of compost. The process of conversion of organic materials into manure is chiefly microbiological and greatly influenced by the proportion of carbonaceous and nitrogenous materials present in organic wastes.

Microorganisms need carbon for cell structure formation and nitrogen for cellular protein synthesis. It was found that C: N ratio of 30:1 or lower for raw material was desirable for efficient composting. So, C: N ratio of organic materials poor in nitrogen should be made narrow by adding nitrogen in the form of any nitrogenous fertilizer to it for better decomposition. Superphosphate is generally added to fortify the phosphorous content of the compost.

Earthworm activities are important in adding faster decomposition process mainly done by microbial actions. An experiment was conducted in Orrisa taking red earthworm (Eisenia foetida) for the decomposition of paddy straw in presence of fertilizer sources to add N and P. Dried and chopped (3-4cm) paddy straw, after thorough mixing with fresh cowdung slurry was introduced into pots. Nitrogen in the form of calcium ammonium nitrate was applied to raise the N level of the straw to 2% N and phosphorus as single super phosphate to raise the total P2O5 content to 0.2%. Watering was done to pots to maintain the moisture content to 40-50%. After 2 week of preliminary decomposition, red earthworms were released at 10 adults per pot. The experimental results showed neutral reaction of the compost masses indicating their suitability for soil application. The straw decomposition was 91% by vermiculture in presence of fertilizer N & P which was greater than the control. The C:N ratio decreased to 10:1 due to earthworm activity alone and further decreased to 8:1 when inoculated in presence of N+P, showing better influence for the decomposition of a wide C:N ratio material like paddy straw. The earthworm population was increased by 16-20 times.