Influence of biologized crop rotations on agrophysical soil properties, crop weediness, and arable land productivity in the arid steppe of the Southern Urals
The research aimed to develop biologized crop rotations and to determine their influence on soil fertility and arable land productivity in the arid steppe of the Southern Urals. The work was performed in 2019-2020 in the Trans-Ural steppe of the Republic of Bashkortostan. The soil was ordinary medium loamy chernozem; the average annual precipitation did not exceed 300 mm. In the experiments, we compared the links of seven-field biologized crop rotations of two types with the six-field grain-fallow crop rotation. Already in the initial period of development, biologized crop rotations influenced soil properties and crop weediness due to the presence of alfalfa and the use of straw for fertilization. The arable layer density decreased to 1.10 g/cm3 versus 1.13 g/cm3 in the grain-fallow crop rotation. The decompaction of the soil contributed to the accumulation of moisture under the alfalfa in the biologized crop rotation. Moisture reserves were slightly inferior to the value of this indicator in the grain-fallow crop rotation - 81-98 mm and 88-106 mm, respectively. Spring reserves of productive moisture in a meter layer of soil against the background of leaving 1.8-2.0 t/ha of straw amounted to 97-98 mm; without its introduction, they were 81-88 mm, which was 12-15% less. In biologized crop rotations by the period of harvesting, the number of weeds was 1.5-2.0 times less than in grain-fallow crop rotations. Owing to optimization of soil properties, decrease in crop weediness, and drought resistance of alfalfa, biologized crop rotations were distinguished by significantly higher productivity compared to the control grain-fallow crop rotations. The average annual productivity of one hectare of biologized crop rotations against an unfertilized background was 1.23-1.25 thousand cereal units, which was 8.8-10.6% more than in the fallow crop rotation; against a fertilized background it was 1.35-1.36 thousand cereal units, or 4.7-5.0% higher than in the grain-fallow crop rotation.