Assessment of the impact of irrigation on the ecological state of gray-brown soils of the Ganja-Kazakh massif

The article presents the results of a study of irrigated gray-brown soils of the Ganja-Kazakh massif, the reasons for changes in individual soil properties associated with the characteristics of specific soil-hydrogeological conditions. It was pointed out that irrigation of gray-brown soils with low mineralized slightly alkaline waters leads to a change in the qualitative composition of salts, an increase in the content of absorbed sodium and its activity. There is also a tendency towards dehumidification of irrigated soils and deterioration of their agrophysical properties. To eliminate the negative effects of irrigation, it is necessary to systematically, comprehensivelyregulate soil processes and regimes. Thus, during irrigation for 50-60 years, the main properties ofgray-brown soils that determine its fertility deteriorated. However, a negative effect of irrigation water with a mineralization of 1.25-2.50 on the salt regime of the soil was noted. Optimization of the reclamation state of soils, prevention of salinization and increase of fertility is promoted bymodern agrotechnical measures in combination with an optimal irrigation regime (68-78% HB), as well as with improving the qualityof irrigation water byreducing its discharge from irrigated fields and the use of chemical meliorants. Since irrigation of gray-brown soils with mineralized waters was carried out on small areas until recently and, as a rule, was not accompanied by a general increase in the groundwater level, secondary salinization of soils is noted locally in the lowered relief elements. In the main irrigation area for most systems, the period of active salt accumulation observed in the first 3-5 years after the start of irrigation stabilizes at the level of 0.12-0.25% in arable horizons and 0.26-0.32% in sub-arable horizons, and they do not leave the gradation of unsalted. Based on the conducted research, generalization and analysis of the literature data, a systematics of changes on gray-brown soils occurring during irrigation was carried out.