EVALUATION OF A TRIPLE LINE SOURCE SPRINKLER SYSTEM FOR SALINITY CROP PRODUCTION STUDIES

Numerous line source sprinkler experiments have been described in the literature, but they do not provide an in-depth analysis of their potential use for salinity crop studies. This work evaluates the advantages and limitations of a triple line source sprinkler system for use in salinity crop tolerance studies. Two outer laterals are used to apply fresh water, while a third lateral centered between them applies saline water. This layout provides duplication of a salinity gradient on each side of the center line while maintaining a uniform application of water. Applied saline water and soil salinity gradients that developed across the laterals on both sides of the center line were correlated (P < 0.001). These gradients were generally linear (P < 0.01) in the 4 yr studied and were not significantly different (P > 0.05) when the laterals were installed parallel to the prevailing wind direction in soils with good infiltration. Soil salinity was uniform at a given distance from the laterals, as indicated by the low coefficients of variation (less-than-or-equal-to 13%) of the electromagnetic sensor readings. Soil salinity increased during the growing season and was higher in the top portion than in the lower portion of the soil profile. This profile distribution was due to limited soil water infiltration. Most of the leaf injury due to foliar absorbed salts was restricted to the lower, older portion of the canopy. This method proves to be useful for salinity crop studies if soils are selected that allow for high leaching fractions, foliar absorption of salts by the crop selected is relatively low, and the system is operated under low wind conditions.