HORIZON MIXING IN SOLONETZIC AND ASSOCIATED SOILS: EFFECT ON DROUGHT-STRESSED BARLEY AND WHEAT

Abstract

Seven placements ranging from natural sequence to complete mixing of the genetic soil horizons in soil columns were applied to six Dark Brown Chernozemic and Solonetzic soils. Two cultivars of barley (Hordeum vulgare L.) and one of wheat (Triticum aestivum L.) were grown in the greenhouse on the columns without watering after initial moistening to field capacity. Soil horizon mixing enhanced crop growth on the three Solonetzic soils but not on the Solodic or the two Chernozemic soils. With horizon placement in the natural sequence, almost half of the roots were contained in the upper 12.5 cm of the column. With complete horizon mixing, root distribution with depth was almost uniform. Maturity and senescence of the plants were delayed on the saline soils compared to the normal stils. The results agree with the known beneficial effects of soil horizon-mixing by deep plowing on some dryland Solonetzic soils and indicate that after such drastic landscape disturbance as occurs in strip mining, the solum should be stockpiled and replaced on the spoil but may be mixed without serious depression of crop productivity. The glacial till subsoils, which were of relatively low salinity in this study, were found to be superior to B and C horizon materials when placed beneath A horizon soil and within the rooting zone of the crop.