Effect of vermicompost/ vermiculture on physico-chemical properties of soil

Abstract

A study was undertaken to assess the effect of application of vermin compost / vermin culture on physic – chemical properties of soil and yield of chilli making use of the soil and plant samples taken from the trial conducted at College of Agriculture, Vellayani. The experiment was conducted during the period from December 1994 to April 1995. The soil of the experimental site was sandy loam. (fine loamy kaolinitic isohypothermic Typic Kandiustults). The experiment was laid out in randomized block design with four replications and six treatments. The treatments consisted of FYM + NPK fertilizers, vermin compost + NPK fertilizers, vermin culture with local worms and with Eudrillussps, vermin culture with above sps. Of worms + basal dose of NPK fertilizers. Soil samples were collected from all the replications of the various treatment before planting, at maximum flowering stage and at harvest. Plant samples were also collected at the above growth stages. Soil and plant samples were analysed in the laboratory to find out the effect of application of vermi compost / vermin culture on physic – chemical properties of soil and content of nutrients in plant parts viz. leaf, shoot and root. Results of preliminary analysis of soil samples collected before the experiment revealed the beneficial effect of application of vermin compost/vermin culture on physic – chemical properties of soil. Physical properties of soil such as bulk density and particle density were found to be much reduced in plots treated with earthworms while porosity was increased in them. Percent of water stable aggregates in plots with insitu application of worms was found to be more than 50 percent but an optimum mean weight diameter of above 0.50 mm was recorded by all treatments. Water stable aggregates with greater than 0.25 mm size had helped to retain more moisture due to the increased intraggregate spaces. The moisture content in soil was found to be more due to the coverage of organic wastes on soil surface. Water holding capacity and hydraulic conductivity were also much influenced by the presence of earthworms. The increased infiltration rate with insitu application of worms to soil indicated the improvement in water permeability of the soil as compared to plots without worms. But surface compaction of soil was found to be not much affected by the application of vermin compost / vermin culture and it showed negative correlation. Application of organic manures either as farmyard manure or vermin compost with inorganic fertilizers had significant influence on soil reaction and organic carbon content of the soil. Organic carbon content was found to be increased with increasing nitrogen rates at both depths of 0 – 15 cm and 15 - 30 cm. Available nutrient contents of the soil viz. available nitrogen, phosphorus and potassium and exchangeable calcium and magnesium were influenced significantly due to different treatments at maximum flowering stage and at harvest. Application of vermin compost + NPK increased the availability of nutrients in soil while application of vermin culture alone with local worms or Eudrillussps. Had resulted in a lower value. Regarding the nutrient content in plant parts such as leaf, shoot and root, all the nutrient contents were highest in the plot treated with vermin compost + NPK fertilizers followed by farmyard manure + NPK. Significant correlation existed between available nutrient in soil and plant nutrient content. Maximum yield and growth parameters were also recorded by the treatment receiving application of vermin compost + NPK fertilizers and the results thus clearly indicate that application of vermin compost along with NPK is essential to maintain high yields. Application of vermin culture alone with local worms or Eudrillussps. Or together with basal dose of fertilizers also failed to give higher yields. Thus by adopting vermin culture technique only the physical properties of soil can be improved while its effect on chemical properties is negligible. So combined application of vermin compost/vermi culture with inorganic fertilizers is found to be better for improving the soil productivity and fertility.