Study of Microbial Population and Enzyme Activities in Intercropped Peanut Rhizosphere with Different Nutrient Application

The aim of this study was to investigate the effect of different levels of chemical fertilizers (CF) alone or in combination with farmyard manure (FYM) under lime or no lime amelioration on biological properties of the rhizosphere soil of peanut, grown as intercrop with sabai grass (Eulaliopsis binata (Retz.) C.E. Hubb) in an acid lateritic soil. The effect of five fertilization levels viz., no CF (F0), CF @ 20:40:30 (F1), CF @ 40:80:60 (F2) kg ha-1 NPK, F1 + 2.5 t FYM ha-1 (F3) and F2 + 5 t FYM ha-1 (F4) with (2 t ha-1) and without lime application were studied on the bacterial density, dehydrogenase and phosphatase enzyme activities (i.e. acid and alkaline phosphomonoesterases), nitrogen accumulation in nodules and phosphorus solubilizing power at 25, 50, 75 and 100 days after sowing of peanut for two years. Results showed significant effects of fertilization levels and growth stages of the crop on the microbial activities. Populations of symbiotic nitrogen fixing and phosphorus solubilizing bacteria, soil enzyme activities, nitrogen accumulation in nodules and phosphorus solubilizing power in the FYM+CF treated plots significantly increased compared to sole CF treatments under both lime and no lime application. Lime application improved the activity of dehydrogenase and alkaline phosphomonoesterase enzymes, while decreased acid phosphomonoesterase activity. This study revealed that integrated application of optimum level of inorganic fertilizer, farmyard manure along with lime could improve the biological properties of an acid lateritic soil as well as the growth of peanut under sabai grass-peanut intercropping system.