Soil and Agrochemical Characteristics of the Svetloyar Irrigated Sitein Volgograd Oblast

摘要

The agrochemical properties of humus-accumulative horizons of irrigated soils on the key site of the Svetloyar irrigation system in Volgograd oblast are analyzed. The field layout before the operation of the irrigation system and a long period of irrigation resulted in redistribution of the carbonate material. Its concentration in the upper part of the soil profile amounted 5-13%, which led to the formation of a dense soil crust and alfalfa crop failure areas (mortality spots). These sites are well detected on the materials of satellite imagery. In the over-45-year period of irrigated arable land exploitation, there has been a significant decrease in the humus content in comparison to arable, nonirrigated lands. The humus content in the soils of thekey sites averaged 1.23% and approached the minimum acceptable level, according to (Metodicheskie..., 2003). The soil degradation is caused by the overall low level of farming culture and the long-term use of the surface irrigation method. The content of mobile phosphorus (20—102 mg/kg) and exchangeable potassium (316— 806 mg/kg) varied widely from medium to very high levels in these soils.