Salinization as a Critical Factor of Land Fertility in the Astrakhan Region
According to the degree of salinization, soils are divided into low, medium, strongly and very strongly saline groups. On low saline soils, crop yields are on average reduced by 25%, on medium saline ones it reduced by 50%, on strongly saline ones it reduced by 75% and on very strongly saline soils it reduced by 100%. In the Astrakhan region, such soils are quite common; this issue is particularly relevant in connection with the reduction in the area of non-saline agricultural soils, as well as with minimal amounts of applied organic and mineral fertilizers. The purpose of the study was to update information on the extent and chemism of salinization of agricultural soils in the Astrakhan region to substantiate measures to prevent secondary salinization. For the local monitoring of the state of soils in the Astrakhan region, 25 reference plots were founded, where soil samples were taken followed by the determination of the quantitative and qualitative composition of inorganic salts. Soil salinization was also assessed in the integrated monitoring of soil fertility of irrigated arable lands. Soils in all areas of the Astrakhan region are subject to salinization to a greater or lesser extent and contain sulfates, chlorides, and bicarbonates. In the region, there is a gradual increase in the area of saline soils on irrigated lands. In the Volga region from 2009 to 2014, the area of non-saline soils of irrigated arable land decreased more than 2 times; in the Kharabalinsky district from 2011 to 2016 it decreased almost 3 times; in Volodarsky and Ikryaninsky districts from 2012 to 2017 the most of the non-saline soils became soils with some salt content. According to the survey results, the largest areas of non-saline soils of irrigated arable land of all districts of the Astrakhan region are located in the territory of Enotaevsky and Akhtubinsky districts.