increasing the thickness of the cultivated layer of soil (to 30–40 cm) and improving its agrotechni-cal properties. Subsoil plowing promotes the accumulation of moisture, intensifies useful microbiological processes and aeration, and increases the content of available nutrients.
Different methods are used for soddy podzolic soils, chernozems, and solonetses. On soddy podzolic soils the subsoil is loosened and mixed with the surface layer. Multilayer plowing is done so that the genetic horizons are shifted, for example, the illuvial to the podzolic. On chernozems deep plowing is done two or three times during a crop rotation. On solonetses the hard solonets horizon is loosened without turning it over onto the surface.
Subsoil plowing is done when a fallow field is plowed or when the soil is worked in the late fall. Simultaneously, organic and mineral fertilizers are added in large quantities and acid soils and solonetses are treated with lime and gypsum, respectively. Green manure (lupine, serradella) is sown, and other methods of improving the plowed layer are used.
REFERENCEGritsenko, V. Obrabotka i uglubleniepakhotnogo sloia pochvy. Moscow, 1971.
Zemledelie, 2nd ed. Edited by S. A. Vorob’ev. Moscow, 1972.
V. S. SHABALINA