| According to the related relationship between soil relative moisture with climate factors and circular factors in spring sowing period of five soil moisture regions in Northeast Area, selected the major impact factor for soil relative moisture, constructed the multiple linear regression models to predict the soil relative moisture during April and May. The results indicated that: (1) The soil relative moisture with freezing rain and precipitation were shown positive correlation in five regions, while negative correlation with the date of soaking rain, temperature and sunshine hours. Moreover the relativity of soil relative moisture with freezing rain and the date of soaking rain in April were more remarkable than in May. (2) The soil relative moisture in spring sowing period for each region was rather close relation with multiple circular factors, the absolute values of correlation coefficients was more than 0.4 and passed the significant test at 0.05 level, also these impact factors were major concentrated in November and December of the previous year. (3) Based on key climate factors and circular index to construct the multiple linear regression models for the soil relative moisture during April and May were total passed the F test and the multiple correlation coefficients were larger than 0.5, also the forecasting precision of model was basically more than 80% with rather high accurac
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