Long-term effect of fertilization on soil chemical and biological characteristics and productivity under sorghum (Sorghum bicolor)_wheat (Triticum aestivum) system in Vertisol

An experiment was undertaken during 2007_08 to study the effect of long-term fertilization and manuring on soil chemical and biological properties in Vertisol. The dynamics of soil characteristics was studied in the on-going longterm fertilizer experiment initiated in rainy (kharif) season 1988 at Akola, Maharashtra comprised 12 treatments including NPK levels with and without FYM, sulphur and zinc replicated four times in randomised block design. The manure and mineral fertilizers were given to sorghum [Sorghum bicolor (L.) Moench] crop every year and only mineral fertilizers were applied to succeeding wheat (Triticum aestivum L. emend Fiori and Paol). Soil samples from all the treatments were collected from 0_20 cm depth. The chemical and biological soil characteristics were studied. Significantly highest increase in soil organic carbon and total nitrogen were recorded with 100% NPK + FYM @10 tonnes/ha. The availability of N, P, K, S, soil microbial biomass carbon and nitrogen, dehydrogenase assay and productivity of sorghum and wheat were significantly increased with the integrated application of organic manure (FYM @ 10 tonnes/ha) and mineral fertilizer (100% NPK) over control and other fertilizer treatments after 20 years of experimentation. Highly significant positive correlation of total productivity was observed with available K, N, and P, whereas moderately positive significant correlation was observed with organic carbon, total nitrogen and biological parameters.