Leaching irrigated saline sandy to sandy loam apedal soils with water of a constant salinity |
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| Authors: | Johannes Hendrikus Barnard Leon Daniel van Rensburg Alan Thomas Peter Bennie |
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| Institution: | (1) Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, Republic of South Africa |
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| Abstract: | With the optimization of irrigation, more salts accumulate in the root zone of soils, due to less over-irrigation. On-farm
irrigation management requires a certain amount of leaching to ensure sustainability. The objective is to quantify the pore
volume of water required to efficiently leach excess salts from two saline soils, widely irrigated in central South Africa.
A total of 30 lysimeters, 15 per soil type arranged in two parallel rows under a moveable rain shelter, were used. Five different
salinity profiles per soil type, replicated three times, were leached using irrigation water with a 75 mS m−1 electrical conductivity. During irrigation the residual more saline pore water was displaced from the top downward through
the root zone. The mean salinity of the soil profiles approached an equilibrium concentration equal to that of the irrigation
water after 0.9 pore volume of soil was displaced by drainage water. For the sandy soil 0.2 and for the sandy loam soil 0.3
pore volumes were required to efficiently remove 70% of the excess salts. The remainder of the water was needed to leach the
remaining 20% of the excess salts. This, however, was not efficient in terms of the amount of water required. |
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