Characteristics of salt accumulation in a sandy soil under saline water irrigation and leaching schedules
2005
Sakaguchi, Y.(Tottori Univ. (Japan). Arid Land Research Center) | Yamamoto, T. | Inoue, M.
A study was carried out using lysimeters to determine the process of salt accumulation in a san dune soil irrigated with salt water. The goal was to find suitable irrigation schedules in sand dune fields. Sorghum (Sorghum bicolor (L.) Moench) was sown in weighing lysimeters uniformly packed with dune sand and plants were irrigated with salt water for two years with different strategies. In the first strategy, the initial soil solution concentration (C) was zero; in the second strategy, the C was same as that of the irrigation water concentration (Ci). Based on the first strategy, the salt storage (S) and salt concentration ratio C/Ci) increased with the number of irrigation but were not affected by the ratio of drainage depth (D) to irrigation depth (I) which is the leaching fraction (LF). The average salt concentration ratio profile in the root zone did not reach the salt concentration ratio profile of a steady state solution. In the second strategy, S and C/Ci reached the steady state condition temporarily and fluctuated according to increasing LF. The salt concentration ratio profile of the root zone reached that of the steady state solution under a steady state condition when the salt input in the irrigation water was equivalent to the output in the drainage water. As a result, two irrigation schedules were suggested for a sand dune field: (i) When the soil solution concentration is zero, the design of the ratio of D to I which is the leaching requirement (LR) should be set at a low level if C is lower than Ci and at a high level if C is greater than Ci. (ii) When C is nearly equivalent to Ci, the LR should be set appropriately, taking into account the salt tolerance of the crop.
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