SIMULATED INTERANNUAL AND SOIL-RELATED VARIATIONS IN PLANTING DATE EFFECTS ON RAINFED SOYBEAN YIELDS

摘要

The effects and interactions of planting date on rainfed soybean yield with interannual climate change and soil type were investigated using CROPGRO- soybean model. Simulations ran for 19 planting dates, Maturity Group Ⅳ, 4 soil types, 30 years weather data from Corbin, Suffolk, West Point in Virginia, USA. Yield was similar on early plantings and went down with late plantings. Interannual variations linearly declined with planting dates. Small interactions occurred between planting date and soil type. Optimal planting dates lied somewhere within 125th ～ 150th day of year for different sites. Irrigation on Bojac soils is recommended for profitable crops.