EFFECT OF FALLOW TYPES ON PROPERTIES OF DARK-CHESTNUT SOILS OF TUVA AND WHEAT PRODUCTIVITY

Abstract

Results are given from the evaluation of fallow types influencing properties of dark-chestnut soils and wheat productivity. When biomass of rape and oats were plowed down, density of the 0-19 cm layer reduced by 0.04-0.08 g/cm3; under favorable weather conditions, rape green-manured fallow contributed to a reduction in soil density to 1.11 g/cm3; plowing down of green manures resulted in increased soil porosity by 3.9-5.5 percent. Investigations of water regimes in crop rotations with various types of fallows under conditions of dry steppe of Tuva showed that bare fallow had more stabile characteristics of moisture availability. Green fallows at the moment of sowing the first crop did not yield to bare ones in available moisture reserves after wet years. The dynamic nitrate nitrogen content is determined by forecrops and weather conditions of a year. Nitrate nitrogen was more accumulated in green fallows during dry years in spring and autumn. During wet years, the nitrate nitrogen content was decreased in all types of fallows. It was revealed that the nitrate nitrogen content before sowing spring wheat on green fallows was more and made up 12.1-12.7 mg/kg of soil (8.5 mg/kg on bare fallow). Spring wheat productivity varies depending on agrometeorological resources, and weakly depends on a type of fallow.