Tuesday, November 6, 2007
184-2

Irrigation with Saline Water: Effects of Soil Hydraulic Properties on Crop Response and Leaching Fraction.

Alon Ben-Gal, ISRAEL, Agric. Research Org., Agricultural Research Organization, Gilat Research Center, Mobile Post Negev 2, 85280, ISRAEL, Shachar Elisha, Department of Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel, Lynn Dudley, Dept of Geological Science, Florida State Univ., Florida State Univ, 111 Carraway Bldg, Tallahassee, FL 32306, Effi Tripler, Arava Research and Development, "Arava" Experimental Station, mobile post Eilot, 88820, Israel, and Uri Shani, The Hebrew University of Jerusalem, JerusaleDepartment of Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Sciences, P.O. box 12, Rehovot, 76100, Israel.

The effect of soil hydraulic properties on water and salt balance of an irrigated crop were investigated in order to evaluate the hypothesis that that crop response to irrigation water salinity is dependent on the soil in which it grows. Simulations from both analytical and numerical models of crop response to the soil environment were applied to the case of tomatoes irrigated with increasing water salinity in three (loamy sand, silt loam (loess) and clay loam) soils with different saturated hydraulic conductivities and water retention properties. Both the analytical and numerical models predict increased average and total soil salinity for soils with lower hydraulic conductivities. The analytical model assumes a single effective value of salinity for the root zone and predicts a corresponding decrease in water uptake and biomass production while the numerical model predicts that areas of relatively low salinity in leached upper layers of the soil are sufficient to supply transpiration requirements without yield loss. The simulated results were compared to experimental data from a series of lysimeter experiments. In the experiments, tomatoes in the loamy sand soil showed lower sensitivity to increasing irrigating irrigation water salinity as compared to those in the heavier soils. The results have particular pertinence regarding economic cost of utilizing saline water for irrigation, determination of leaching requirements and estimations of water and salts leaving agricultural fields.