Regularities of water consumption of grasses in forest pastures by types of agricultural landscape in the Volga steppe zone

Abstract

Water consumption and productivity of grasslands are closely related to the type and degree of protection from erosion of the agricultural landscape. One of the main indicators of the type of agricultural landscape is the slope of the slope, which determines the level of soil fertility and productivity of agricultural land. With an increase in the slope, especially on erosive types of agricultural landscape (>30), the thickness of the a+B horizons decreases by more than 3 times from 64 cm on the plakor (<10) to 20 cm on steep slopes (10-200). The humus content in the soil horizon a decreases from 4.69 to 1.97%, or 2.72% in absolute value. Over 35 years, the complex of anti-erosion techniques has increased the power of soil horizons A+B, depending on the type of agricultural landscape, by 1-6 cm, the content of humus-by 0.16 - 0.36%, NPK – by 9.1-30.0%: a larger increase corresponds to the erosive types of agricultural landscape (>30). Productivity and water consumption of pasture lands depend on the level of soil fertility, snowiness of winters, the degree of moisture in the growing season, and the growth dynamics of pasture grasses. In the average humidification years (2015,2016) on open types of agricultural landscape, the productivity of grasses was 1.23-3.14 t / ha, the coefficient of water consumption -675-1538 m3 / t, and under the influence of anti-erosion techniques, respectively-1.73-4.05 t/ha and 627-1242 m3/t. The difference in water consumption coefficients reaches 23.8% on steep slopes (10-200). In dry years with the previous snowy winter on open types of agricultural landscape, the coefficient of water consumption is 930-1500m3/t, under the influence of anti-erosion techniques-703-1169 m3/t, or less by 32.7-28.3%. In wet years, the water consumption coefficient takes the lowest values due to the high productivity of grasses (5.61-8.89 t/ha). The complex of anti-erosion agrotechnical and forest-reclamation techniques is created in accordance with the type of agricultural landscape: on slopes with a steepness of 0-50-forest strips and mulched crevices; 5-80-forest strips and shrubby scenes; >80 - protective forest stands on terraces.