Assessment of nitrate nitrogen supply in soils of the forest-steppe zone using soil diagnostics

The purpose of the study is to generalize and evaluate the provision of nitrate nitrogen in arable soils of natural districts of the Krasnoyarsk Region depending on various factors and conditions. We summarized the results of a continuous agrochemical survey of soils for the content of nitrate nitrogen in three natural districts of the Krasnoyarsk Region: Central and Western, South Minusinsk and Eastern groups of districts included in the agrochemical service zone. We systematized the long-term results of an agrochemical survey on the content of nitrate nitrogen in the soils of the study objects depending on the following factors: weather conditions, predecessor, soil tillage. The influence of three methods of basic treatment of a fallow field on the content of mineral forms of nitrogen (dump processing, disking and cultivation) was studied. The soils were grouped according to the supply of soils with nitrate nitrogen, depending on the listed factors. Agrochemical survey of soils on farms in the forest-steppe zone of the Krasnoyarsk Region for the period 2011-2019 indicates that the proportion of fields with different groups according to the supply of nitrate nitrogen in different years was unequal, depending on the weather conditions of the year. Dry conditions during the growing season significantly reduced the activity of nitrate accumulation. Fallow fields do little to accumulate nitrates. Only 50 % of the fallows from the surveyed fields justify their purpose as optimal nitrogen precursors. The supply of nitrate nitrogen for grain crops, row crop predecessors, fallow, rapeseed and even perennial grasses is low and very low. A weak ability for nitrate accumulation was noted in soils of fields cultivated without moldboard. After cultivation, 40.7 % of the surveyed fields are characterized by a low supply of nitrate nitrogen; after disking, 46.2 % of the fields have very low nitrogen content. Dump processing promotes active nitrification. In most cases, plowing is significantly superior to non-moldboard cultivation. The following decreasing series of influences of factors on the intensity of nitrate accumulation and the provision of soils with this form of nitrogen has been formed: weather conditions > precursors > soil tillage methods.