Predicting summer rice yield based on biophysical and technological parameters on monsoon lands of Brahmaputra valley, India.

摘要

A deterministic approach for the crop grain yield function that follows reciprocity law of diminishing return to fertilizer use is adopted to simulate the effects of biophysical dynamics and fertilizer use for summer rice yield in the Brahmaputra valley. Variations in the potential yield of rice, a frontier parameter of the yield function, and the parameter related to reproductive yield which acts as a coefficient of Fertilizer Use Efficiency (FUE) are assessed by using the biophysical attributes of land (soil and weather) in terms of Potential Productivity Index (PPI) for paddy crop growth as submodel of the function. The model and submodels were parameterized with collecting monthly precipitation and temperature statistics over 15 (1975-90) years of seven meteorological stations located in the Brahmaputra valley, the soil texture data of three major soil types (new alluvial, old alluvial and piedmont) and the statistics relating to summer rice yield and fertilizer use for different areas for a period of 28 (1975-2003) years from various government agencies. Grain yield of summer rice increases at a constant rate as PPI increases. However, the intensive use of fertilizer diminishes its (rice yield) rate in a specific biophysical scenario because of decreasing FUE in presently employed yield function..