NITROGEN REGIME OF LEACHED CHERNOZEMS OF THE NOVOSIBIRSK OB REGION WHEN APPLYING MINERAL FERTILIZERS IN THE GRAIN CROP ROTATION

It was found that in a meter-thick layer of chernozem leached in a pure bare fallow field crop rotation: bare fallow-wheat-wheat-wheat steam can accumulate up to 70 kg / ha of nitrate nitrogen, 50–70% of which is concentrated in a layer of 0–40 cm, and the supply of plants very high. The content and reserves of nitrogen in the layers 0–40 and 0–100 cm of soil in all variants of the experiment had a high direct relationship with the reserves of productive moisture, the correlation coefficients (r) were 0.88–0.99 and 0.84–0.98, respectively. Mineral fertilizers applied by various methods in the form of fertilizer with nitrogen, phosphorus and potassium (Azofoska) at a dose of 43 kg a. s. / ha did not compensate for the nitrogen removal by spring wheat; their supply of plants at the end of the crop rotation remained very low. At the same time, 50–70% of its reserves were concentrated in the 0–40 cm soil layer. The greatest absorption of nitrogen by microorganisms in the arable soil layer occurred in the control, and mineral fertilizers reduced it by 2 times. Nitrogen deficiency in the soil on average for 3 years in the control was 30 kg / ha, and with the introduction of azophoska in rows, scattered and locally – 23; 10 and 9 kg / ha, respectively. The largest increase in wheat yield and payback of 1 kg of a. s. of mineral fertilizers with grain was obtained with spread and row application – 23 and 26% to the control and 10 and 11 kg / kg, respectively, the smallest – with local – 9% and 4 kg / kg.