Agroeconomic justification for plowing spring wheat straw when using increasing doses of mineral fertilizers in the forest-steppe of the Trans-Urals

The purpose of research is an agroeconomic justification for the plowing of by-products generated when growing spring wheat on various agricultural backgrounds. Research was carried out in field conditions in the northern forest-steppe of the Trans-Ural Region from 2013 to 2016 on leached arable chernozem. The experimental options included the introduction of increasing doses of mineral fertilizers necessary to obtain a yield of 3.0 to 6.0 t/ha of grain. The natural agricultural background was used as a control. After harvesting the grain crops, the straw was crushed by a combine and scattered among the experimental options. Accounting for the mass of straw and its selection for experiments was carried out during sheaf analysis, after which the accompanying indicators of the content of nitrogen, phosphorus and potassium were determined. It was established that the yield of spring wheat in the variant with a natural agricultural background on average over the years of research amounted to 2.0 ± 0.1 t/ha of grain, while the straw yield reached 2.4 ± 0.1 t/ha. The application of mineral fertilizers in a dose from N40P10 to N180P140 kg a.m./ha ensured the formation of from 3.0 ± 0.1 to 4.9 ± 0.2 t/ha of grain and straw from 4.6 ± 0.3 to 6 .4 ± 0.3 t/ha. The nutrient content in plant residues grown in the variant with a natural agricultural background was: nitrogen 0.69 ± 0.05 %, phosphorus 0.18 ± 0.01 and potassium 0.67 ± 0.02 %. In the fertilized variants, the NPK content in spring wheat straw was higher than the control and reached: nitrogen 1.15 ± 0.5 %, phosphorus 0.22 ± 0.1, potassium 1.10 ± 0.02 %. After harvesting activities, nitrogen - 17 kg/ha, phosphorus - 4, potassium - 16 kg/ha - is returned to the soil with plant residues grown under control (without fertilizers). The use of mineral fertilizers for the planned yield of spring wheat led to an increase in nutrient reserves in the straw: nitrogen 39-74 kg/ha, phosphorus 9-14, potassium 43-68 kg/ha. The cost of nutrients contained in spring wheat straw is 1870 rubles/ha. For fertilized options - 4519-7852 rubles/ha. The main share falls on potassium - up to 60 %, nitrogen - up to 30 % of the cost of nutrients. We recommend that in fields where the yield is more than 4.0 t/ha of grain, the straw should be chopped and plowed.