The article presents the results of field trials on the effect of cover crop of alfalfa on the humus content in the soil and ameliorative status light meadow saz soils. It was revealed that the cover crop alfalfa helps increase humus in the soil after the alfalfa from 6 to 14,7 percent in the arable and sub arable soil horizons. At the end of the experiment in the soils of the experimental plot chlorine ion content decreased to 0,003% and the sulfate ion to 0,023% by weight of soil.