Collector-drainage water reuse for crop irrigation: Experiment on saline lands of southern Kazakhstan

As a consequence of global climate change and the resultant recurring periods of drought and water scarcity, the ecological status of irrigated lands in southern Kazakhstan has deteriorated. One of the largest massifs in terms of area is Myrzashol, located in the south of the Turkestan region. Field experimental studies have been conducted on this array over the past 25 years. Experimental work was carried out on saline, abandoned, old-irrigated lands of this massif. As a result of the development of secondary salinization and salinization of soils, the area of irrigated lands with varying degrees of salinity increased from 50.4 to 99.2 thousand hectares or 2 times. In all, the irrigated area under consideration contains approximately 147.0 thousand hectares of land. Of this area, 67% has varying degrees of salinity. An increase in the concentration of salts in the soil not only reduces crop yields, but also disrupts the soil structure and porosity. This, in turn, negatively impacts the soil’s water permeability. As a result, the land with such soils is excluded from agricultural production due to low productivity and ineffective irrigation. This article presents the results of field studies to determine the effect of irrigation with mineralised collector-drainage water (CDW) on the yield of cotton and alfalfa using CDW with a mineralisation of 2.4 to 4.0 gram/litre (g/l). A control site was used for comparison, where these crops were irrigated using fresh irrigation water with mineralization levels of up to 0.5 g/l. Additionally, we explored the feasibility of using collected water for the irrigation of agricultural crops. Based on the findings from field experiments, it has been concluded that using CDW with sulphate-type mineralisation levels up to 4.0 g/l to irrigate cotton and salt-resistant alfalfa forage crops on saline soils can lead to production yields of 27.1 centners per hectare (hereinafter - c/hа) and 155.0 c/ha for cotton and alfalfa, respectively, without depleting valuable freshwater resources. These harvests are considered lucrative for this type of land without requiring the use of fresh water.