Potential for Improving the Yield of Field Crops on Chestnut Soils of Dry Steppes in West Siberia

The research was carried out to assess the potential for improving the yield of soft spring wheat, oats, and sunflower on chestnut soils of the dry steppe in the south of West Siberia to increase the arable land productivity. The study was conducted in 2016–2023 in a long-term stationary field trial in the West Kulunda subzone territory of Altai krai. The experimental design provided for a comparative study of the effectiveness of field crop rotations in the conditions of different saturation with wheat and sunflower against unfertilized and fertilized (N₃₀) backgrounds. On chestnut soils of the dry steppe, the effect of nitrogen fertilizers was determining in changing the yield of wheat on bare fallow (factor contribution 87.4%), strong in changing the yield of oats (68.2%) and sunflower (57.5%), significant in changing the yield of wheat on nonfallow predecessors (36.8%), and appreciable in arable land productivity (24.2%). The effect of crop rotation was determining (74.2%) in changing arable land productivity, strong in the yield of wheat on nonfallow predecessors (62.5%), significant in the sunflower and oat yield (41.4 and 31.5%, respectively), and weak in the yield of wheat after fallow (11.7%). The most favorable conditions for wheat and sunflower were formed for wheat on fallow predecessors when placed after oat; that for oat was after wheat in cereal—fallow-row crop crop-rotations with one sunflower field. The trial minimum productivity of arable land was in crop rotations without sunflower (460…570 gr. un./ha). With a sunflower proportion of 16.7…25%, this value increased in relation to cereal–fallow crop rotation and continuous wheat by 160…280 gr. un./ha (28.1…60.9%) and that with 50% was by 310…420 gr. un./ha (54.4…91.3%). Application of nitrogen fertilizers under crops of cereal–fallow-row crop and cereal–row crop crop-rotations ensured an increase in arable land productivity by 150…250 gr. un./ha (20.5…28.4%) in relation to unfertilized background with payback of 1 kg of nitrogen up to 8.33 gr. un.