THE ROLE OF GRASS CROP ROTATION IN THE FOOTHILLS OF THE REPUBLIC OF NORTH OSSETIA – ALANIA

The purpose of the study is to identify the effect of grass crop rotation crops on the physical, agrobiological parameters of soils and on crop productivity in the forest-steppe zone of North Ossetia – Alania. Objectives: to study the structural and aggregate composition of the soil; to determine the volumetric mass of soil under crop rotation crops; to identify the general biological activity of the soil, the effect of crop rotation on their productivity. The object of the study is grass crop rotation cultures. The studies were conducted in 2020–2022 in the field stationary crop rotation of the SKNIIGPSH VSC RAS in the conditions of the forest-steppe zone of the Russian North Ossetia – A. The soil of the experimental plot is represented by leached chernozems on pebbles, where humus ranges from 3.4 to 4.7 %. The experiments were carried out in triplicate. The area of the experimental plots is 100 m2, and the registration plot is 96 m2. It was established that at the beginning of the growing season, the blocky fraction under rotation crops varied from 13.50 to 50.10 %, and soil lumps from 0.25 to 10 mm (macrostructure) – from 49.40 to 82.60 %, fraction < 0 .25mm – from 1.80 to 8.0 %. The structure coefficient varied from 2.22 % (corn) to 2.49 % (oats + clover). Research has proven that leached chernozems contain from 45.0 to 66.5 % of aggregates that resist the erosive action of water, due to which these soils have a good structure. Over the years of research on oats + clover crops (on average 0–30 cm soil layer), the soil density was 0.95 g/cm3 at the beginning of the growing season, 1.19 g/cm3 during the period of intensive growth, 1.22 g/cm3 – at the end of the growing season. This trend is evident in all crop rotations. In our research on the collection of feed units, the grass link of the crop rotation was highlighted, where the total indicator was 15.05 t/ha, and in the row crop link of the crop rotation – 13.12 t/ha. The highest indicators of metabolic energy in the grass section of the crop rotation were obtained for winter wheat and amounted to 4.76 GJ/ha, and in the row crop link for grain corn – 8.13 GJ/ha.