MONITORING OF THE SOIL AGGREGATE COMPOSITION UNDER VARIOUS CROPS IN THE MOUNTAINOUS ZONE OF NORTH OSSETIA
Monitoring of soil agrophysical research in the conditions of development of erosion processes on slope and mountain soils is due to the need to preserve soil fertility for the future generations. The structural and aggregate composition is one of the indicators of the agrophysical soil fertility. It also justifies the changes occurring in the soil under the influence of the external environment (natural factors) and the intensity of its agricultural use. The research was carried out at the mountain long-term station of NCSCMFA (a branch of VSC RAS) in Dargavs village. The study of erosion processes on mountain meadow soils in the Dargavs basin led to the determination of many indicators of soil fertility (bulk mass, structure of the arable layer, soil moisture, water resistance of the soil structure, accounting for runoff and washout). The blocky structure amounted to 21.7-62.9 %, the macrostructure amounted to 35.6-78.0 % and the microstructure amounted to 0.3-7.4 %. Tillage with mechanical tools led to the destruction of the blocky structure and their number was reduced by half. The destruction of the blocky structure led to an increase in macroaggregates, while the content of silty fractions also significantly increased by 1.8-2.2 times. Soil structures were destroyed under the influence of raindrops, mechanical treatments and humus losses due to removal with crops and erosion processes, which led to an increase in the blocky and dusty fraction and a decrease in the structural coefficient. The structural coefficient for comparable options decreased by 1,74 units. So in crops of perennial grasses it decreased by 0.9 units, oats by 2,36, winter rye by 3.5, potatoes by 2.02. The average value of the first period of research provided an average value of 2.96 for crops and it is 1.52 units at present.