Soil salinity modeling over shallow water tables. I: Validation of LEACHC

Soil salinity is a very common problem in today's irrigated agriculture. Hi gh salinity levels adversely impact crop yields and reduce overall soil qua lity. The presence of a saline shallow water table can be a major contribut or to this problem. The LEACHC version of LEACHM is one of the few numerica l models that considers independent movement of individual ions along with their detailed chemistry. This model has apparently not previously been tes ted under saline shallow water table conditions. LEACHC was evaluated using both lysimeter and field data from the literature. The model performed rea sonably well in simulating solute transport above a saline shallow water ta ble. For both data sets used in model validation, less reactive ions (sodiu m and chloride) were predicted well while calcium concentrations were under predicted. For the field data, the model predicted soil electrical conducti vity (EC) profiles better than most of the individual ions. The water conte nt profiles associated with the field data were also predicted quite well. Based on these results, LEACHC was selected as a simulation tool for evalua ting the effects of management practices on salinity transport in crop root zones above a saline shallow water table.