Characteristics of long-term temporal and spatial variation of corn field soil moisture and relationship between soil moisture and corn yield in South Heilongjiang

Based on the observation data of soil moisture during corn growing season(from May to September) in 1983—2009 from 15 agro-meteorological stations in South Heilongjiang Province,with the statistical method of the climatic tendency rate and trend coefficient,using of GIS spatial analysis module,the characteristics of spatial and temporal variations of soil moisture and relationship between them at different growth stages of corn growing season in South Heilongjiang Province were analyzed.The results showed that: Soil moisture during different growth stages of corn in 1983—2009 had a decreasing trend and was significantly positively correlated to precipitation;The spatial distribution of soil moisture was obviously different in various areas,the soil moisture was normal or relatively higher in Sanjiang Plain and the middle agricultural area,while it was relatively lower in western Songnen Plain.The spatial distribution of annual change trend rate of soil moisture showed that: Most of the Middle East Songnen Plain and most of Mudanjiang area had a decreasing trend, only a few areas showed an increasing trend.In the dry areas of Qinggang and Tailai in western Songnen Plain,corn yield and the actual growth period of each growing season and soil moisture showed a significantly positive correlation,and partial dry or wet soil had a adverse influence on corn yield.