2017 ASHS Annual Conference

The lower Colorado River region of the southwestern United States is the location of a multi-billion dollar vegetable industry. Water and salt management are of paramount importance to agricultural sustainability in this region. This region has been challenged to utilize water resources more efficiently but data was limited to estimate annual water and salt balance across the cropping systems. The objective of these studies was to quantitatively track water use and salt balance across typical crop production systems and rotations. Electromagnetic surveys (EM38), augmented with soil samples, were used to estimate spatial and depth related salinity distributions. Water measurement flumes, water depth sensors, soil moisture and salinity sensors, and data loggers, were utilized to measure in-flow hydrographs during irrigation events and quantitate the water delivered and water and salt redistribution in the soil. Eddy-Covariance (ECV) instrumentation was used to track water evapotranspiration losses from fields over the cropping season. Overall, the data show in-season irrigation application efficiencies are high, often approaching or exceeding 90%. Much of the required leaching for salt occurs in irrigation events outside those applied to the major vegetable cash crop, including the rotational lower value crop. Future implications for salt management and the prospects for further improvement in water application efficiency will be discussed.