Development of fallow gray forest soils of the forb-bromegrass stage

Abstract

The experiments were carried out on a 0.5-hectare field plot of the Siberian Federal Scientific Center of Agro-Biotechnologies of the Russian Academy of Sciences; the plot was untilled for more than 30 years. The findings obtained made it possible to study the physical and mechanical properties of the vegetation cover of gray forest soils at the forb-bromegrass stage: the average thickness of the sod layer was 8-10 cm; the degree of sodding - 24.36 g dm²; the sod breaking strength - 1.18 N cm². The presence of roots in the root layer of 10 cm was 7.6 kg m²; at a depth of 10-20 cm - 0.6 kg m². The measurements of soil hardness showed that a force of at least 28 kg cm² was required to puncture a sod layer with the tip of a hardness tester at a moisture content of 20%. At a depth of 25 cm, soil hardness stabilized in the range of 18 kg cm², and at a depth of 40 cm it reached a value of 15 kg cm². The highest soil hardness, over 40 kg cm², was observed at a low moisture content of 10-13% within the A horizon where the humus layer was located. The stubble-breaker “KL-2.5N” was proposed to till the fallow soils. This stubble-breaker is equipped with a special coulter with a moldboard which allows lifting and loosening the sod layer of soil. In the version without a roller, the coulter cuts off the sod layer from the soil, loosens it and creates conditions for drying the root parts of the plants. In the version with a ring roller with a diameter of 600 mm, at repeated tillage, it frees the rhizomes of plants from the soil, creates the necessary structure and levels the field surface. The method of introducing previously abandoned gray forest soils into arable lands is substantiated; the most effective agronomic method is the tillage of the fallow with the stubble-breaker “KL-2.5N”. Already after the third tillage with the stubble-breaker “KL-2.5N” with moldboards and a roller, the soil is suitable for sowing grain crops. At the same time, the number of soil particles less than 10 mm is more than 93%, and the number of particles more than 50% is only 1.38%.