The contribution of perennial fodder crops to the nitrogen balance of agroecosystems in Western Siberia

Abstract

The article presents the results of experiments obtained in stationary experiments on the basis of grain-fallow and grain-grass crop rotations on meadow-chernozem soil in the Omsk region. The influence of spring wheat precursors (alfalfa of the 3rd year of life and fallow) on individual elements of soil fertility and crop yield has been established. It was revealed that when cultivating spring wheat by fallow in the grain-fallow crop rotation, the nitrogen balance (-28 kg/ha) is negative with an intensity of 66 %. When sowing wheat in grain-grass crop rotation on a layer of perennial grasses, the nitrogen balance is positive (+21.0 kg/ha) and the intensity is 119 %. The favorable effect of the legume component in the crop rotation on the nitrogen regime of the soil significantly increased the yield of spring wheat by 0.5 t/ha in comparison with wheat cultivated in the field crop rotation by bare fallow. Under similar conditions, studies were carried out on irrigated meadowchernozem soil in an eight-field stationary grain-grass crop rotation. The removal of nitrogen by the yield of various perennial grasses, as well as the responsiveness of alfalfa, bromus and sweet clover with productivity parameters to the level of nitrogenphosphorus nutrition, were studied. The current mobilization of nitrogen under these conditions under the vegetative brome without fertilizers was 76 kg/ha. When optimizing the phosphate regime of the soil, this indicator increased to 99 kg/ha. The removal of nitrogen by alfalfa on similar agricultural backgrounds increases due to symbiotically fixed nitrogen, by 89 and 193 kg/ha, respectively, or 2.2 and 2.9 times. Alfalfa and sweet clover responded positively to the improvement of mineral fertilizing conditions (P60N60-160). In alfalfa of the 1-5 year of life the collection of green mass and fodder units increased to 40.56 and 7.00 t/ha, respectively, or by 86 and 54 % relative to the control without fertilizers, with 82.76 GJ of exchange energy per hectare. The productivity of sweet clover of the 2nd year of life increased up to 30.85 t/ha of green mass and 2.83 t/ha of fodder units or by 37 and 17 % relative to the control.