Influence of the predecessor, sowing period and fertilizer in wheat productivity in three-field crop rotations

For the first time, 18-year-old experimental data were analyzed, in which the influence of 3 growth factors of spring soft wheat – a precursor (fallow, vico oatmeal mixture, oats), the sowing period and nitrogen fertilizer were compared. The experiment was carried out under conditions of a 3-field crop rotation on the heavy loamy leached chernozem of the Shadrinsky experimental field of the Kurgan Research Institute in the northwestern zone of the Kurgan region. In influencing the yield of the first wheat, the leading role was played by the previous crop in combination with weather conditions. When comparing the yield during sowing in the 1st and 3rd decades of May, after all 3 predecessors for 14 years, the early period was outperformed. When sowing in the 1st decade of May, the grain harvest of the first rotation crop without fertilizer decreased from 24.8 c/ha after fallow to 16.8–15.8 c/ha after non-fallow precursors. At the 2nd sowing period, the conditions for the formation of the crop were more favorable and ensured the production in the same fields 30.3–21.1–20.5 c/ha, respectively. The yield of the 2nd crop rotation was less. Without fertilizer after the predecessors, it was obtained accordingly 17.5–16.8–15.1 c/ha at the 1st sowing period and 19.5–20.2–18.9 c/ha – at the 2nd term. The fertilizer increased the yield of the first crop mainly after non-paired precursors by 6–9 kg/ha. The yield of the 2nd crop increased with the use of fertilizer after all 3 predecessors, increasing grain harvest by 5–8 kg/ha. The influence of wheat yield growth factors on the accumulation of gluten proteins in grain was greater at an early sowing period and for the first crop rotation. It was more noticeable in the field after fallow: the absence of the 3rd grade of grain quality during early sowing after fallow was noted once in 18 years, when sowing in the 3rd decade – 5 times. The effect of the fertilizer on the gluten content of 1st wheat manifested itself after the non-paired precursors, but only at a dose of N80 and was expressed in its increase by 2–5%, respectively. For 2 crops, the average gluten content, depending on the sowing period, was the same both without fertilizer and with its application. The number of years without grain with grade 3 quality was also almost equal, both for all types of predecessor and the sowing period. An improvement in grain quality from fertilizer was noted in all crop rotation fields and also only at a dose of N80 with an increase in gluten content from 25–26 in the control to 29–30%.