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Secondary salinization of irrigated lands in drylands is often caused by rising groundwater levels. Open drainage is widely employed to control groundwater. However, salinity levels tend to remain high under malfunctioning drainage conditions. Shallow subsurface drainage may be a possible solution to prevent salt accumulation, although it is difficult for farmers to apply conventional tile drainage systems owing to construction costs. In this regard, we proposed a low-cost shallow subsurface drainage system used in combination with a new mole-drain drilling technology (cut-drain) developed in Japan, whose drainage capacity is similar to tile drain. The aim of this study is to evaluate the effect of the proposed system. The system was installed in a farmland, Uzbekistan. The experimental field was set with/without the system to observe the differences in the balance of water and salt. The results revealed that the remaining infiltrated water in the field decreased by approximately 26% and the removed net mass of salt was 14 Mg ha−1. The direction of salt movement changed from the deeper zone or surrounding field to the open drainage. Therefore, the proposed system can enhance salt removal from fields.

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Skip furrow irrigation (SFI) can save water by irrigating every alternate furrow. Usually, irrigated furrows are alternated at each irrigation event under SFI. If irrigated furrows are fixed (permanent SFI, PSFI), more water may be saved by reducing the wetting area, and salts may accumulate on the dry side of the ridge. Salt removal sheet, a method of collecting salts on the sheet laid on the soil surface utilizing high evaporation demand in drylands, may be an efficient measure for removal of accumulated salt under PSFI. We evaluated salinity movement and water saving under PSFI through a field experiment in Uzbekistan. In addition, a salt removal sheet was applied to the shoulder of the ridge on the drier side under PSFI to evaluate its potential in removing salt from the soil with the practice. The results showed that salts tend to accumulate on the dry side of the ridge, and the amount of irrigation water was halved without a large crop yield reduction. The PSFI + Sheet was able to catch 6.4% of salts in the top 10 cm soil layer.

Foreign approaches to maintaining a favorable salt regime of soils are analyzed. On the basis of experimental studies, a change in the water-physical properties of the soil during deep loosening and an increase in salt leaching during leaching and vegetation irrigation using the Biosolvent preparation were established. Based on the analysis of the leaching results, the optimal technologies and norms for leaching saline soils have been established.

On the irrigated saline soils of the Syrdarya region of Uzbekistan, the leaching capacity of the Biosolvent desalination device has been studied. The experiments were carried out on bulk soil columns, as well as in the field: during the period of land leaching and irrigation of cotton. Field experiments and phenological observations of plants were carried out according to generally accepted methods. Soil analysis methods follow: texture, -by method of sedimentation; salinity -by measurement of electrical conductivity, in the soil-water suspension (1:1); ionic composition, -by method titration and gravimetric in a soil water extract 1:5. When leaching the soils on the columns with a 2% solution of the preparation, as well as when spraying the soil with a 10% solution of it, before pouring water, the leaching of HCO3Ca and Mg ions increases most of all. By field experiments on soil leaching, with preliminary treatment of the surface inside of the checks with the preparation in a ratio of 1:10, the efficiency of salt leaching increased by 35 ... 42%. This will save 2000 m3 / ha of water, with a drug consumption of 10 l/ha. Testing a preparation for treating the surface of furrows before watering cotton to reduce salt stress on plants showed an increase in salt leaching by 18-23%. As a result of improved conditions in the root zone of cotton, an increase in yield of 7.5 c / ha was obtained. The use of this preparat to reduce seasonal soil salinization in the fields is available to farmers.