A Comparative Study on Dynamic Forecasting of Early Rice Yield by Using Different Methods in Hunan Province

The crop yield forecasting is one of the most important aspects of meteorological services for agricultural production. In order to improve the prediction accuracy, different forecasting methods are compared, and dynamic forecasting models of early rice yield are established based on climatic suitability, key meteorological factors and crop growth simulation model. Daily mean, maximum and minimum temperatures, precipitation, sunshine duration, wind velocity and vapor pressure data of 15 representative meteorological stations are used, as well as the early rice growth and yield data of 12 representative agricultural meteorological stations in Hunan Province from 1962 to 2002. Fitting test is performed by constraining the margin of error less than 5%. Extrapolation test is performed using data from 2003 to 2012, showing the accuracy of three methods are similar, all higher than 93.8%, and the dynamic forecasting models practically pass the test of 0.02 level, except for failing the test of 0.10 level on 30 April. Forecasting models from rifeness tiller to elongating stage pass the test of 0.01 level, and forecasting models at reproductive stage pass the test of 0.001 level too. The method based on climatic suitability improves the accuracy by 4%-6% comparing to that based on key meteorological factors and is 8%-10% more accurate than that based on crop growth simulation model. In quantitative forecast, the method based on crop growth simulation model is optimum, leading to obviously more samples whose margin of error is less than 5%. According to the analysis, the better method of early rice yield forecasting is screened out for Hunan Province. The method based on climatic suitability is chosen to carry out trend prediction of early rice yield, and the method based on crop growth simulation model is used to make quantitative forecast. It also provides reference for dynamic forecasting method research of early rice yield in other areas of China.