OPTIMIZATION OF HUMUS CONTENT IN DARK CHESTNUT SOILS OF WEST KAZAKHSTAN

Abstract

There is shown a change in the humus content in dark chestnut soils of West Kazakhstan in connection with long-term anthropogenic impact. A general tendency to humus losses in the process of the long-term agricultural use was found for this type of soils. The calculations have shown that an annual humus loss in dark chestnut soil makes up 0.6-1.1 tons per ha. Changes in the humus content are given for different soil tillage techniques: plowing, cultivation with shovels at the depths of 25-27 cm and 12-14 cm, and zero tillage. The use of cultivation with shovels at the depth of 25-27 cm in a crop rotation resulted in a significant increase in the humus content in the 0-40 cm soil layer as compared with plowing to the same depth. It has been established that, to create positive humus balance in dark chestnut soils in four-course rotations, there should be applied 12-16 tons of manure per ha annually. Under current conditions established in agricultural production of the region, when manure application is problematic, the question of replenishing organic matter in the soil can be solved by introducing perennial grasses into crop rotations with emergency fields.