CONTENT OF MAIN NUTRIENTS IN ORDINARY CHERNOZEM AND PRODUCTIVITY OF FIELD CROPS IN CROP ROTATIONS AT MIDDLE TRANSVOLGA AREA
The importance of long-term use of mineral fertilizers, plant residues, soil treatment systems in the accumula- tion of basic nutrients in ordinary chernozems of the Middle Transvolga, and the high efficiency of the application of mineral fertilizers in the transition to savings systems for their use has been established. The introduction of siderates and perennial grasses into crop rotation, as well as the use of straw as fertilizers, increases the content of nitrate nitrogen by 32-35%, the mobile phosphate by 7.0-7.6% and stabilizes the potassium regime in compari- son with the cereal crop rotation. This makes it possible to increase the payback of fertilizers, which must be tak- en into account when developing systems for the reproduction of soil fertility. With the long-term application of modern technological systems for tillage and sowing, the supply of soils with nitrogen is stabilized, the content of mobile phosphates in it increases by 14.1-17.8%, the exchangeable potassium content by 14.9-22.7%. The highest productivity of crop rotation (1.82 tons of feed units/ha) was established with differentiated tillage, which is 2.8-5.2% higher than other options.