Water Management in Agriculture

Water Management in Agriculture

The Relation between Irrigation Water Salinity and Soil Salinity

Authors
1 Assistant Professor, Fars Agricultural and Natural Resources Research Center
2 Assistant Professor, National Salinity Research Center.
Abstract
A clear understanding of the relation between irrigation water and soil salinity is necessary for precise analysis of data obtained from salinity experiments or from field observations. Soil salinity is expressed in terms of salinity of saturation extract (EC­e) and soil solution) ECss with the use of EC­e being more common. Often it is assumed that soil salinity (EC­e) is always greater than irrigation water salinity (ECiw). However, EC­e can be less or greater than ECiw. The determining factor in setting this relation is the amount of leaching fraction. In the layer within the root zone where leaching fraction is high, EC­e is less than ECiw. Field data show that EC­e within the root zone can even become less than half of ECiw. It is also shown here that EC­e in the interval between two irrigation episodes does not change and remain constant, while ECss increases with time because of the crop water uptake.
 
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چراغی، س. ع. م. و کریمی، م. 1388. ارزیابی مدیریت­های بهره‌برداری از منابع آب‌وخاک شور در باغات پسته شمال اردکان، گزارش نهایی. مرکز ملی تحقیقات شوری. 88 ص.
Ayers, R.S. and Wescot, D.W. 1985. Water quality for agriculture. Irrigation and Drainage paper. No. 29, Rev. 1. FAO, Rome.
Hanson, B.R. and Grattan, S.R. 1999. Agricultural salinity and drainage. University of California. Irrigation Program.
Letey, J., Hoffman, G.J., Hopmans, J.W., Grattan, S.R., Suarez, D. L., Corwin, D.L, Oster, J.D., Wu, L
and Amrhein C., 2011. Evaluation of soil salinity leaching requirement guidelines. Agricultural Water Management, 98:502–506.
Mass, E.V. and Hoffman, G.J. 1977. Crop salt tolerance- current assessment. Journal of the Irrigation and Drainage Division, 103(2):115-134.
Rhoades, J.D. 1972. Quality of water for irrigation. Soil Science, 113:277-284.
Rhoades, J.D., Kandiah, A. and Mashali, A.M. 1992. The use of saline waters for crop production. Irrigation and Drainage paper. No. 48, FAO, Rome.
Richard L.A, 1954. Diagnosis and improvement of saline and alkali soils. US Department of Agriculture, Agricultural Handbook No 60, Washington (USA), 160 p.
Suarez, D.L., and Simunek J. 1997. UNSATCHEM: Unsaturated water and solute transport model with equilibrium and kinetic chemistry. Soil Science Society of America Journal, 61:1633-1646.
Van Dam, J.C., Huygen, J., Wesseling, J.G., Feddes, R.A., Kabat, P., van Walsum, P.E.V., Groenendijk, P. and van Diepen, C.A., 1997. Theory of SWAP version 2.0. Simulation of water flow, solute transport and plant growth in the SoilWater-Atmosphere-Plant environment. DLO Winand Staring Centre.
Wagenet, R.J. and Hutson, J.L. 1987. LEACHM: Leaching Estimation and Chemistry Model: A Process-based Model of Water and Solute Movement, Transformations, Plant Uptake and Chemical Reactions in the Unstaturated Zone. Cornell University, Centre for Environmental Research.
.