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This study was undertaken to test the hypothesis that an improved system of catchment management in combination with appropriate cropping practices can sustain increased crop production and improve soil quality of Vertisols, compared with prevailing traditional farming practices. Initiated in 1976, the improved system consisted of integrated land management to conserve soil and water, with excess rainwater being removed in a controlled manner. This was combined with improved crop rotation (legume based) and integrated nutrient management. In the traditional system, sorghum or chickpea was grown in the post-rainy season with organic fertilizers, and in the rainy season the field was maintained as a cultivated fallow. The average grain yield of the improved system over 24 years was 4.7 t ha(-1) yr(-1), nearly a five-fold increase over the traditional system (about 1 t ha(-1) yr(-1)). There was also evidence of increased organic C, total N and P, available N, P and K, microbial biomass C and N in the soil of the improved system. A positive relationship between soil available P and soil organic C suggested that application of P to Vertisols increased carbon sequestration by 7.4 t C ha(-1) and, in turn, the productivity of the legume-based system, thus ultimately enhancing soil quality.
