Modelling corn production in China using AVHRR-based vegetation health indices

Weather-related crop losses have always been a concern for farmers, governments, traders and policy makers for the purpose of balanced food supplies, demands, trade, and distribution of aid to nations in need. Therefore, early crop loss assessment in response to weather fluctuations is an important issue. This paper discusses the utility of Advanced Very High Resolution Radiometer (AVHRR)-based vegetation health indices as a proxy for modelling corn yield and for early warning of drought-related losses of agricultural production in China. The indices were tested in Jilin province on corn yield during 1982-2001 using correlation and regression analysis. A strong correlation between corn yield and the vegetation health indices were found during the critical period of corn growth, which starts 2-3 weeks before and 2-3 weeks after corn tassel. Following the results of correlation analysis, several regression equations were constructed where vegetation health indices were used as independent variables. The estimates of corn yield can be carried out well in advance of harvest and the errors of the estimates are 7-10%. The errors become smaller when the estimations are related to losses in corn yield due to drought.