Long Term Influence of Manure- Fertilizer Treatments on Soil Biological Health and Yield of Rice Crop

Abstract

Long term manure fertilizer experiments provide valuable information on the impact of long term adoption of nutrient management systems with varying sources, types and combinations of plant nutrient inputs on soil fertility and productivity. A Permanent Manurial Experiment (PME) under rice monoculture is in operation since 1975 at the central farm of the Agricultural College and Research Institute, Madurai. The present study was taken up to evaluate the effects of different manure – fertilizer schedules on certain properties of the soil, available nutrient status, total microbial population and enzyme activities of the soil. In this experiment, four main plot treatments involving three organic manures viz., FYM, GLM and UC @ 12.5 t ha-1 with a no manure control and eight sub plot treatments viz., control N,P,K,NP,NK,PK and NPK. The 57th rice crop (Var ADT 49) was raised during rabi 2016 with NPK recommended dose of 150:50:50 kg N, P2O5 and K2O respectively. The maximum total bacterial population (128 x 106 CFUg-1 of dry soil), total fungal population (70 x 104 CFUg-1 of dry soil) and total actinomycetes population ( 84 x 103 CFUg-1 of dry soil) were registered in the plots that received integrated application of GLM @ 12.5 tha-1 and 100% recommended NPK (150:50:50 kgha-1 during this season). However compared to the bacterial population, the inorganic fertilizers did not have much influence on the fungal population as that of the organic manures. Integrated application of GLM @ 12.5 tha-1 along with N fertilizer with or without P and K registered the maximum dehydrogenase activity, during tillering stage of rice crop. The maximum yields of rice grain and straw (4790 and 8701 kg ha-1) respectively was recorded in the treatments that received GLM and NPK and it was evident that the inclusion of FYM or GLM or Urban compost along with NPK, N, NP, and NK fertilizers recorded significantly higher yields than their individual applications and unmanured and unfertilized control.