Nitrate nitrogen’ intrafield and temporal variability in the Western Siberia fields

The paper presents the results of studying the intra-field and temporary inhomogeneity of the content of nitrate nitrogen. The survey found that there are several types of soil on the field: dark gray forest soil, leached chernozem, meadow chernozem, meadow solodized and solod. All soils belong to the heavy loamy variety. Research involved determining the contour of each soil within the boundaries of the studied field. Determination of nitrate nitrogen was carried out from May to September in 2018-2020. In the course of the experiments carried out, a variation in the content of nitrate nitrogen in the arable layer was established both in space and in time. Before sowing grain crops, the average content of nitrates in the field was 6.3 mg/kg, varying from 3.8 (malt) to 8.2 mg/kg (meadow-chernozem soil). Each soil in the field had its own characteristics of nitrogen dynamics during the growing season. The maximum variability in the content of nitrates was noted in the dark gray forest soil - 11-38 %; the minimum spread is in the meadow solod (Cv = 3-9%). The presence of the application of mineral fertilizers during the study of spatial and temporal heterogeneity was due to the formation of various hydrothermal conditions of the arable layer, which affect the activity of nitrifying microflora. This is the rationale for the need to form elements of soil plots based on the soil cover of fields. It was found that the variability of the content of nitrate nitrogen depends on the type of soil and the time of the growing season with an influence of 21 and 24 %, respectively. The nature of the annual dynamics of nitrates in soils is manifested to a minimum (the influence of the factor "year" - 4 %).