To evaluate the effect of leaching irrigation on the spatial distribution of soil salinity, an electromagnetic induction method (EIM) was used to track the salt dynamics of poorly drained fields during leaching irrigation in the Hetao irrigation district. In a 0.3-ha study area, we observed soil salinity and micro-topography at over 700 points, and the groundwater level and salinity at 17 points, between 2002 and 2003. Spatial analysis was used to determine the inter-relationships of soil salinity, irrigation water path, and groundwater. After leaching irrigation, soil salinity in the root zone was reduced temporarily. During the observation period, the distribution of soil salinity did not change greatly. Lateral flow of groundwater was quite slow and there was little difference in groundwater salinity before and after irrigation. There was a good correlation between groundwater salinity and soil salinity.
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