Productivity of crop rotations with perennial grasses and leguminous crops in the dry-steppe zone of the Lower Volga region.

The research was carried out in the fields of the Lower Volga Research Institute. The work was completed in 2017-2020. The soil of the experimental site is light chestnut, heavy loamy, with a humus content of 1.74% in the arable layer. The average annual precipitation was 339.7 mm. The technology of cultivation of these crops was generally accepted for the research area. The placement of options (A) is sequential and options (B) are placed in blocks in three tiers. The main tillage in the experiment is soil-free, treated with a SibPME stand to a depth of 25-27 cm. Zoned varieties of agricultural crops are cultivated. Records and observations were carried out according to the recommendations. During the period July-August, the largest amount of precipitation fell in 2016 -- 119.0 mm; the smallest in 2017 -- 6.0 mm, in other years this indicator was in the range of 32.8-86.0 mm. On average, over the years of research, the largest accumulation of crop residues, straw and roots in a 4-pole crop rotation with black steam is 3.4 t/ha. The amount of nitrogen entering the soil with straw and crop residues was noted in an 8-month crop rotation of 49.8 kg/ha. The largest amount of biological nitrogen (according to Trepachev's method) was accumulated under alfalfa crops of 34.4 kg/ha. The analysis of soil samples for the content of humus over the years of research did not reveal significant changes. The best precursor for winter wheat is black steam. For perennial grasses, peas, the grain yield of winter wheat in some years is reduced by 4- 12 c/ha. The analysis of the correlation dependence of crop rotation productivity showed that the highest dependence with precipitation for May-June is t = + 0.50 for grain and feed units and slightly less for protein-t = +0.26-0.50. [ABSTRACT FROM AUTHOR]