Assessment of fertility agroecological parameters of agro-gray soils when laying a field experiment

The purpose of research is to study the patterns of fertility variability in agro-gray soils of a production area intended for conducting a field experiment with phosphorus-potassium fertilizers. The study was carried out on the company Sukhobuzimskoye land areas in the Krasnoyarsk forest-steppe of the Krasnoyarsk geomorphological district, located within the Chulym-Yenisei denudation plateau in the southwestern outskirts of Central Siberia. Its geographical position is determined by the coordinates 56°26' N and 92°54' E. The object of study is an agro-gray, medium-humus, medium-thick, light-clay soil on red-brown clay, formed on a stepped, slightly sloping southern macroslope of the Shila-Minderla interfluve with pronounced erosion ledges. The heterogeneity of the land plot was studied by reconnaissance survey of the territory, using methodological approaches to the study of highly varying soil properties at close distances. The results of an agrochemical survey of agro-gray soil revealed a slightly acid reaction of the environment, a low content of humus, ammonia nitrogen, mobile phosphorus, and an average supply of mobile potassium. The variability of agrochemical indicators was wide-ranging: the minimum was found for the reaction of the soil environment, the maximum was characteristic of ammonia nitrogen compounds. In general, in descending order of the level of variability, the indicators were distributed in the following decreasing series: N-NH4 (60 %) > humus (19 %) > P2O5 (13 %) > K2O (10 %) > pHH2O (4 %). For the studied soil properties, a strong spatial dependence (10 %) was found, which is associated with the position of the sampling points. The calculated values of the soil-ecological index (SEI) and the soil-agro-climatic index (SAC) were relatively low: 32.0 and 29.6 respectively. At the same time, the "humus content" had an impact on the decrease in the soil coefficient, and the "availability of mobile phosphorus" - on the decrease in the agrochemical index.