Organic recycling for soil quality conservation in a sub-tropical plateau region

The long-term effect of organic recycling on some aspects of quality in a lowland rice soil of an Indian plateau region was studied. The experiment was set up at the agricultural experimental farm of the Indian Statistical Institute, Giridih, Bihar, India. Two rice cultivars, and treatments with four organic supplements (cowdung manure, Leuceana leaves, decomposed farm residue and Sesbania), chemical fertilizers (urea, superphosphate and muriate of potash) and no input were arranged in a factorial randomized block design. Organic supplements improved soil quality parameters such as water holding capacity, total organic C, microbial biomass C, urease and acid phosphatase activities of soils in comparison to chemical fertilizers and no input. Among the organic supplements, cowdung manure gave significantly higher organic C (1.39%), microbial biomass C (276.46 mu g g(-1) dry soil), urease activity (32.79 and 21.22 mu g urea hydrolized g(-1) dry soil h(-1) at 37 degrees C by the buffer and non-buffer method, respectively) and acid phosphatase activity (1.99 mu mol p-nitrophenol released g(-1) dry soil h(-1) at 37 degrees C) than the others. The conversion of organic C into biomass C (2.46%) was highest in Leuceana-treated soil.