Spring soft wheat yield variation in the Republic of Tyva steppe zone under the hydrothermal conditions, precursors and mineral fertilizers influence

The purpose of research is to study the effect of year conditions, predecessors and nutrition levels on the yield of spring soft wheat. The study was carried out in the steppe zone of the Republic of Tyva on dark chestnut, medium loamy soils, in a three-field crop rotation with a short rotation (pure fallow - wheat - wheat; pure fallow - perennial grasses - wheat; pure fallow - oats - wheat) permanent wheat, on two backgrounds nutrition: without the use of fertilizers (control, background 0), the use of fertilizers - (background 1). The best predecessors of spring soft wheat were perennial grasses and pure fallows. In moderately wet years, the yield of wheat after perennial grasses and bare fallow averaged 2.62 t/ha, in excessively wet years - 1.35 t/ha. This is due to the high content of nitrate nitrogen in the soil in the initial period of growth and development of wheat according to these predecessors. The use of mineral fertilizer increased the yield of spring wheat after perennial grasses and bare fallow in moderately wet years by an average of 4.2 %, and in excessively wet years by an average of 21.9 %. Moisture reserves in the spring depended more on the hydrothermal conditions of the previous year of research than on the predecessors. Fallowing in moderately wet years accumulated 19.5 % more productive moisture than other predecessors. In excessively wet years, the best moistening conditions were formed after perennial grasses with fertilizer application, where the productive moisture was 4.5 % more than in the control.