Assessment of the dynamics of the main agrochemical indicators of irrigated chestnut soils under risk farming conditions in Stavropol

Irrigation is an important element of agricultural production in the arid conditions of the Stavropol Territory. The combination of irrigation, chemicalization and complex mechanization provides highly productive use of land that requires specific scientific support. The purpose of the research is to identify differences in the dynamics of the main agrochemical indicators (organic matter, pH, mobile phosphorus, mobile potassium) on irrigated and non-irrigated chestnut soils. The object of research is chestnut soils located in an extremely arid climatic zone of the Stavropol Territory. The data of complex monitoring of soil fertility in the Apanasenkovsky district were used as the source material. The data for the period from 1991 to 2020 were prepared by the staff of the State Center for Agrochemical Service “Stavropolsky”. The content of soil organic matter was determined by the Tyurin method in the modification of CINAO. Mobile compounds of phosphorus and potassium were determined by the Machigin method in the modification of CINAO. The value of the hydrogen pH index of the aqueous suspension was determined by the potentiometric method. The content of organic matter in chestnut soils increased from 1.8 to 2.0–2.1% both on irrigated and non-irrigated lands. A tendency to leaching of irrigated lands by 0.2 units has been revealed; therefore, in this case, it is recommended to use chemical ameliorants. Moreover, on irrigation, an increase in the content of mobile phosphorus (from 0.8 to 4.0 mg/kg) compared to non-irrigated areas was revealed. The reason for this is the increased doses of phosphorus-containing fertilizers applied during irrigation. During the study period, the content of mobile potassium increased from 77 to 93 mg/kg irrigated chestnut soils compared to non-irrigated ones. The negative dynamics in the content of mobile potassium on irrigation was revealed. It amounted to 364 mg/kg (as of 2020), which is lower than the data of the previous survey period by 81 mk/kg. Particular attention should be paid to the use of potash fertilizers since there is increased removal of this element, despite the high potash potential of chestnut soils in the arid zone of the Stavropol Territory.