Application of Grey System Theory Evaluating the Influencing Factors of soil Salinity

Dynamic monitoring the topsoil and plow pan soil Electrical Conductivity(EC) and the influencing factors continuously in the Yangtze River Estuary,the degree of association of soil EC and the influencing factors was established by applying the theory and method of grey system in 2006-2007.The results showed that the degree of association in topsoil was Ground water depth Evaporation Groundwater ECFreshwater ECPrecipitation River water EC,and in plow pan soil was Ground water depthGroundwater ECPrecipitationEvaporation River water ECFreshwater EC.The water table was the most active and straightforward factor to topsoil EC and plow pan EC.For the topsoil the evaporation and Groundwater EC were the second influence factors,the precipitation increased the leaching and could lower the topsoil salinity content.For the plow pan soil,Groundwater EC,Precipitation and Evaporation all had big correlation.In addition the three factors'value was similar.So the grey system method is simple and ideal method to analyze the soil salinity.