Revanuru, Sucharitha (ICRISAT, Patancheru, AP, India, Buldg 212/First Floor, Systems Modeling, ICRISAT, Near Hyderabad, AP, 502324, India; Phone: 91 4030713438; Fax: 914030713075; Email: s.revanuru@cgiar.org)

Simulation of the Effects of Manure Quality, Soil Type, and Climate on N and P Supply to Sorghum and Pigeon pea in Semi-Arid Tropical India

S. Dimes, S. Revanuru *

Experimentation in India examined the response of sorghum and pigeon pea to inputs of low and high quality manures on N and P responsive alfisol and vertisol soils. A special feature of the work is that inorganic fertilizer treatments were included to help quantify the cereal and legume responses to the N and P content of the manure. This paper provides a brief overview of the Indian experiments and results, and reports on the performance of APSIM to simulate aspects of the observed legume and cereal crop responses to N and P inputs, and the residual legume benefits to a following cereal. For this preliminary evaluation, the model performed poorly in simulating the observed P response at low N levels. However, further modifications to input parameters for the P model, especially in relation to P supply and uptake for deeper soil layers may improve the fit between observed and predicted results. In contrast, APSIM performed well in predicting the growth of pigeon pea and the residual N benefits to a following cereal crop, including the response to additional inputs of N fertilizer.