Classification and Causes of Soil Degradation by Irrigation in Russian Steppe Agrolandscapes

Abstract

This chapter covers the causes of soil degradation in irrigated agrolandscapes of Russia. The most significant causes are the extensive use of irrigated arable land and the unfavourable chemical composition of irrigation water. This is especially pronounced in the absence of land reclamation measures. As yet, there is no accepted classification of soil degradation due to irrigation. In this chapter, a classification for the degradation of irrigated soils was developed. Five types were proposed, divided into sub-types. Physical degradation includes the deflation and reorganisation of the soil mass. Chemical degradation suggests the unbalanced removal of biophilic elements or the excessive accumulation of harmful substances. Physico-chemical degradation manifests in negative changes in the soil absorption complex (SAC), which triggers other negative changes. Biological degradation is associated with a decreased content of organic matter in soil and unfavourable biota succession. Hydrological degradation occurs due to negative changes in the soil water regime. The degradation degree indicates how intensively the degradation processes manifest, while the speed of degradation shows the activity of negative changes over time. The nature of the degradation reflects the specificity of the degradation processes. The reversibility of degradation indicates a soil’s ability to restore its original properties. The resistance of soil to degradation is an indicator for the soil’s ability to maintain its productive and environmental functions.