Productivity of grain-fallow crop rotation with black fallow in southern forest-steppe of Western Siberia
The research data for 2016-2021 on the effect of chemicalization background on the formation of spring wheat grain yield in a field grain-fallow four-field crop rotation with black fallow (fallow - wheat - wheat - wheat) are presented. Soils of the field is meadow-chernozem moderately deep low-humus and medium-loamy. Autumn processing was conducted on black fallow for 20-22 cm. During the fallow period early spring harrowing and four times cultivation with harrowing were made. Herbicide Puma Plus EC (1.4 l/ha) was used either on the first or second crop after fallowing. After fallowing two types of fertilization background were also used. First one was used annualy without fertilizers and with adding ammophos (N<sub>12</sub>P<sub>52</sub>) when sowing the first crop. With the second and third crops ammonium nitrate (N<sub>30</sub>) was added. Wheat varieties “OmGAU 90ˮ (2017-2019) and “Stolypinskaya 2ˮ (2020-2021) were sown with a disc seeder at the rate of 4.5 million germinating grains per hectare. The use of herbicide on the first crop after fallow on a fertilized background provided additional grain of only 0.11 t/ha, and on the unfertilized one - 0.31 t/ha. On the second crop after fallow, the fertilization background was enhanced by the introduction of ammonium nitrate (N<sub>30</sub>). The difference with the variant without fertilizers increased to 0.52-0.56 t/ha. On the third crop after fallow, the advantage of the fertilized background decreased to 0.35-0.39 t/ha. Optimal solution is to use herbicide Puma Plus, EC (1.4 l/ha) and ammophos (N<sub>12</sub>P<sub>52</sub>) on the first crop and ammonium nitrate (N<sub>30</sub>) without herbicide on the second and third crop. The grain yield from one hectare of crop rotation area amounted to 2.48 tons.