DYNAMIC FORECASTINGMODELS OF SOIL MOISTURE IN WINTER WHEAT AND SOYBEAN FIELDS IN SHALLOW GROUNDWATER LEVEL

The calculating model of phreatic water evaporation in the Jianghuai region is given by means of statistic and water balance methods. According to the water balance principles of crop fields, the dynamic forecasting models of soil moisture in winter wheat and soybean fields with phreatic water evaporation and without phreatic water evaporation are built. The forecasting accuracy of the two models in a condition of shallow groundwater level is compared. The results in 1980 show that the mean absolute errors and mean relative errors of the former for seven periods of two crops are 8.2 mm and 2.8% and the mean absolute errors and mean relative errors of the latter for seven periods of two crops are 20.1 mm and 6.8%. The forecasting accuracy of the dynamic forecasting models of soil moisture in winter wheat and soybean fields including phreatic water evaporation is improved notably.