Crop rotation as a basis of soddy podzolic soil fertility of Upper Volga
On soddy podzolic soil in Upper Volga, the productivity of biological crop rotations with various content of grain and legume crops under different conditions of mineral nutrition and soil treatment are studied. The proportion of legume grasses is 25 and 50%. Moldboard ploughing decreases soil density by 0.03-0.04 g/cm3 compared to subsurface tillage. Crop rotation containing 50% legume grasses have the largest average content of plant residues in soil 41.5-50.7 dt/ha dry matter. The use of legume crops and mineral fertilizers (NPK)90 contribute to maintaining labile phosphorus and potassium in soil at a medium and high level. The content of exchangeable potassium also depends on soil treatment. Options with clover of the first year within 4- and 6-field crop rotations and winter rye within a 4-field rotation with moldboard ploughing exceed subsurface tillage systems in terms of potassium content. Crop yield based on mineral fertilizers is higher than the control by 7.1-9.4 dt/ha unit. When it comes to tillage, the efficiency of a 4-field crop rotation exceeds subsurface tillage by 14%, 6-field rotation by 8%. Crop rotation has less impact on yielding capacity. In a 6-field rotation, it is higher by 2-7% on average than in a 4-field due to a greater level of organic matter and improvement agrophysical soil properties. The greatest profitability shows the 6-field rotation in terms of moldboard ploughing and amounts to 53% as control and 83% on a fertilized soil.