Effectiveness of early fallow on Steppe chernozems

Abstract

Topicality. Clean fallow is a reliable means of drought control, increasing productivity and sustainability of Steppe agriculture. At the same time, a fallow remains the most vulnerable field of the crop rotation, which requires perfect methods of maintenance that can counteract erosion processes, prevent humus losses, and improve the moisture availability of wheat. Purpose. To determine the soil protection and agrotechnical effectiveness of early fallow (sunflower, stubble, maize) when growing winter wheat in the conditions of the Northern Steppe of Ukraine. Materials and methods. The primary tillage of clean fallow was carried out with heavy cultivators, combined units, and plows. The erodible resistance of chernozem was assessed by field modeling and hydrological methods, to frost heaving – by soil lumpiness and the amount of post-harvest residues. The water-physical properties of the arable layer were determined in accordance with generally accepted methodical recommendations, the yield – by direct harvesting, and the grain quality – in accordance with DSTU 3768:2019. Results. It was established that maintaining arable land according to the early fallow scheme contributes the soil deflation and erosion control. At the same time, the migration of fine soil outside the field does not exceed 1.5–4.3 t/ha per year. The introduction of early fallow after cereals and row crops contributes to additionally accumulate productive soil moisture in the amount of 130–150 m3/ha compared to the control (plowing 25–27 cm) and restore moisture reserves for the spring tillering of wheat plants (207–221 mm or 86–92 % of the ultimate field water capacity, 0-150 cm layer). On sloping lands, the two-phase tillage of early fallow is preferable, which includes strip loosening to 40–45 cm depth in late autumn and shallow loosening to 14–16 cm depth in spring. In terms of productivity of winter crops, early fallows are not inferior to fall tillage. On the plains, the best variant of fallow maintenance was variant, which combines mulching with the cultivation of cover crops, on the slopes – with soil slitting. When involving all by-products of predecessors in the cycle, it is advisable to feed plants with nitrogen fertilizers in the spring with a dose of N30-60. The application of mineral nitrogen provided an average wheat yield on early fallow at the level of 5.52–6.66 t/ha and food grain with a protein content of 11.5–11.9%, gluten - 22.6–24.6%. Conclusions. Maintaining arable land according to early fallow scheme reliably protects the soil from erosion and ensures the restoration of productive moisture reserves to the level of 86–92% of the ultimate field moisture capacity in the second year. According to the wheat grain yield, spring tillage (12–16 cm) was not inferior to autumn plowing (25–27 cm). The effectiveness of early fallows is enhanced by soil slitting, cultivation of post-harvest (cover) crops, optimization of nitrogen nutrition of plants. Key words: early fallow, winter wheat, tillage, post-harvest residues, fertilizers, erosion, moisture, yield, grain quality