Key Words

SOIL HEALTH, VERMICOMPOST, C/N RATIO, EARTHWORM

Introduction

Most of the biodegradable organic waste can be converted into vermicompost. When earthworms feed on organic waste, it under goes physical and chemical breakdown during the process of ingestion and digestion. The recycling of waste through earthworm is called as vermicompost. Two important things were considered in preparation of recipes for the quality production of vermicompost. First, food preference by earthworms and second, carbon and nitrogen ratio. Lindwrt (1941) studied the mechanism of eating of broad leaf litter by some earthworms. The abundance of earthworm species differ with C/N ratio of the soil organic matter (Kale and Krishnamoorthy, 1981). The earthworm Lampito manritii showed preferences to leaf litter. The preferences vary with references to dry leaf matter and to disintegrating leaf in soil. Caron and nitrogen of the leaf is not the criterion for this appetitive and consumatary behaviour. It is discussed that probably volatile potentiators or modifiers in leaf are responsible for feeding behaviour of the worms.

In composting process, the ratio of carbon and nitrogen (C/N) is one of the important parameter, which gives an indication of rate of decomposition. Gaur (1992) suggested that a C/N ratio of 30:40 is optimum for efficient composting. When material with a high carbon content is used with a C/N ratio exceeding 40:1, it is desirable to add nitrogen supplements to ensure effective decomposition (Ismail, 1997).

Materials and Methods

Recipes were prepared by mixing different waste materials in different proportions. The recipes were prepared with balanced C/N ratio. The C/N ratio of the organic material should be below 40:1. To maintain this ratio the organic waste were mixed with green mulch, following organic waste were used for vermicomposting.

Waste material (approximate) C/N ratio
Saw dust 400:1
Paddy straw 80:1
Wheat straw 100:1
Leaf litter (mango leaf) 54:1
Cattle feed waste 75:1

These organic waste were mixed with nitrogen rich materials e.g. cow dung (20:1), leguminous plant leaves e.g. dhaincha leaves (25:1), babul leaves (30:1), bean leaves (12:1) to enhance decomposition and maintain C/N ratio below 40:1. Five types of recipes were prepared in different combinations by mixing organic waste, cow dung and leguminous. These five type of recipes were subjected to vermicomposting studies with three species of earthworm i.e. Eudrilus eugeniae, Eisenia fetida and Perionyx excavatus in plastic pots.

Experimental Details

Design : Randomized complete Block Design (RCBD)

Treatments : 3 with worms + 1 without worms (control) i.e., 4 treatments

Replication : 3 (Three)

No. of pot : 4 x 3 (12 pots in each set of experiment

Total 5 set of experiment were arranged.

Total pots required for whole experiment 12 x 5 = 60 pots.

Chemical analysis of the vermicompost was done in Agricultural Chemistry lab by export for NPK and C/N ratio

Results and Discussion

Two important things should be considered in preparation of recipes for the quality production of vermicompost.

(i) Food preference

(ii) C/N ratio of the substrates used for preparation of recipe.

(iii) Food preference by earthworm: The mechanism of cating of broad leaf litter by some earthworms was studied by Lindwist (1941). Kale and Krishnamoorthy (1981) reported that the earthworm Lampito mauritii showed preferences to leaf litter. Hatanbe et al. (1983) reported that sludged cake when supplemented with cellulose material such as rice straw proved to be good growth medium. The dung of cattle, sheep, horses, pigs or dropping of poultry birds form the ideal feed for earthworms. Wheat bran, gram bran and vegetable waste when added to dung in 10:1:1:1 ratio would enhance the biomass production. poultry dropping and cow dung in 1:1 ratio are an appropriate diet in mass production of earthworms (Bano and Kele, 1984). Kale and Bano (1988) reported that mix dung and grass was a good diet for earthworms. Ratekar (1992) reported three farm waste, kitchen waste in combination with cow dung were good medium for multiplication of earthworms. Manna et al. (1994) reported the maize stover as the most suitable amongst the food material used e.g. wheat straw, maize stalk, chickpea straw, soybean straw and city garbage for the growth of earthworms.

In the present investigation the recipes were prepared by mixing the cow manure and green mulches with the different organic waste materials which are in correspondence with the reports of the different workers. C/N ratio of the substrates used in preparation of recipe: C/N ratio of the recipe affect the decomposition process and quality of vermicompost. Gaur (1992) suggested that a C/N ratio of 30-40 is optimum for efficient composting. A C/N ratio of 25 resulted in the highest stability of the product and best fertilizer value of the production (Ndegwa and Thompson, 2000). Ismail (1997) suggested to add nitrogen supplements to get a C/N ratio below 40:1. Senapati and Dash (1982) reported that plants can not assimilate mineral (nitrogen) unless the C/N ratio of vermicompost falls around 20 or below.

Keeping in view the above pacts the recipes were prepared by balancing by balancing the c/n ratio of the substrate in the present investigation. The recipes were mixed with green mulches to get a C/N ratio below 40:1. The findings are in correspondence with the suggestions of gram (1992) and Ismail (1997).

Thus, the recipes prepared was subjected to feed. Thus, the recipes prepared was subjected to feed the earthworms species Eudrilus eugeniae, Eisenia fetida and Perionyx excavatus. The earthworms showed better survival and fast multiplication in all recipes. The vermicomost preduced after feeding the worms have increased nitrogen, phosphorus and potash (table-2). These findings were in aggrament with the findings of Singh and Rai (1997), Vashanthi and Kumarswamy (1999), Probodhini (1994), Edwards and burrows (1998). Balasubramaniam and Bai (1995) reported that the nitrogen content of the worm casts increases with the supplementation of organic waste as feed. The C/N ratio of end products of all recipes was decreased below 20:1 in 120 days of composting by earthworms. This observation corroborate with the findings of Jadrijeric et al. (1991). Talashilkar et al. (1999), Dash and Scnapati (1985, 1986), Elvira et al. (1996, 1998). Manna et al. (1997) also reported a reduction of C/N ratio during vermicomposting due to addition of earthworms.