Monitoring soil salinity

SUITABLE inventories of soil salinity do not exist in the United States, nor are there monitoring programs to track the salinity status of soils. National or state programs to protect soils against salinity are likewise nonexistent. Proper operation of a viable, permanent irrigated agriculture, which also uses water efficiently, requires periodic information on soil salinity. Only with this information can the effectiveness of irrigation project operation be assessed with respect to salt balance and water use efficiency. The need for monitoring will likely increase. Less water will be available for leaching as the competition increases for water now used in irrigation. In addition, restrictions are expected to be placed on the discharge of salt from irrigation projects. With less leaching, there will be a corresponding increase in soil salinity. Monitoring soil salinity is complicated by salinity's spatial variability. Numerous samples are needed to characterize an area. Monitoring is also complicated by salinity's dynamic nature, due to the influence of management practices, water table depth, soil permeability, consumptive water use, rainfall, and salinity of the perched groundwater. When the need for repeated measurements is multiplied by the extensive requirements of a single sampling period, the expenditures of time and …