The role of clay fraction and humus in the formation of the field moisture capacity of arable chernozems

During the plowing of virgin chernozem of leached and prolonged use in arable fund of the forest-steppe zone of Western Siberia revealed changes one of the main indicators of water-physical properties - the field moisture capacity. In studies conducted in the period from 1968 to 2016 has been used of field method. The article describes the material to study the migration of clay fraction in the soil profile; the dynamics of stocks of humus, changing the field moisture capacity and the range of active moisture. The soil of the station is leached chernozem medium loamy medium rich. The station has been created on the virgin site in 1968. After detailed study of the properties, part of it was under cultivation to the present time used in plowing. Re-examinations were held in 1990, 2006 and 2016. Found that prolonged use of the chernozem of the arable land decrease and the lowest ratio of 7.7 % on the initial data. This had a negative impact on the range of active moisture that decreased from 231 to 196 mm. The maximum anthropogenic change of the studied parameters observed in the layer 0-50 cm. Migration of clay particles from the arable horizon is revealed. In 48 years their contents has decreased from 28 to 26 %. Between the field moisture capacity and the proportion of clay fraction strong positive correlation (r = 0.79). Accumulation of silt in the lower part of the profile meter was the cause of the deterioration of the range of active moisture, as evidenced by a high inverse relationship (r = -0.58). For 48 years, the reserves of humus in arable chernozem decreased by 10.4 % compared to virgin soil. Identified a close positive correlation between (r = 0.91) between the reserves of humus and the field moisture content in the 0-50 cm layer of leached chernozem.