THE EFFECT OF ALFALFA STAND ON SURFACE RU NOFF AND WATER EROSION

Effect of alfalfa stand on runoff and erosion manifestations mentioned on sloping locations was studied in a system of Six elementary model basins. Inclination (slope gradient) of individual pairs of basins amo unted to 3, 8 and 12%. Rainfall surface runoff and erosion soil washin g were classified in Tab. II and characterized mathematically as funct ional dependence of growth height (three variants: a - stubble, b - 4 to 25 cm, c - 26 to 60 cm) and rain intensity (F-D) calculated from da ta mentioned in Tab. I. Functional dependence of runoff coefficient (p hi) on rain intensity can be expressed as follows: a) phi = 0.10 F-D - 0.06; b) phi = 0.07 F-D - 0.08; c) phi - 0.05 F-D - 0.08; calculated values related to erosion soil washing (m(e)) are expressed analogical ly: a) m(e) = 11.67 (F-D - 1); b) m(e) = 1.33 (F-D - 1); c) m(e) = 0.5 6 (F-D - 1). Results of the study demonstrated significant positive hy drological role of alfalfa. Erosion washing on grown alfalfa locations was as much as 250 times smaller and on alfalfa stubbles as much as 2 7 times smaller as compared to unsown locations.