Crop yields in reference areas of the forest-steppe zone of the Omsk Irtysh region

The research is based on the results of local monitoring carried out in 1994–2018 on reference sites established on agricultural lands. The purpose of the research is to identify the level and patterns of changes in yields and regulatory agrochemical indicators on the zonal soils of the forest–steppe of the Omsk region. The objects of research were cultivated plants (spring wheat, barley, oats, potato, corn, sunflower, alfalfa, awnless brome) of the forest-steppe zone of the Omsk region at reference sites located at the enterprises “Druzhba” of the Gorky district (soil - ordinary thin low-humic heavy loamy chernozem), “Pushkinsky” of the Omsk region (meadow-chernozem moderately deep medium-humic heavy loamy soil), and “Yuryevskoye” of the Kormilovsky district (meadow-chernozem deep low-humic light loamy solonets). The level and patterns of changes in yields and standard agrochemical indicators on zonal soils are revealed. The coefficient of used nutrients from the soil in grain crops for nitrogen is 88–95%, for phosphorus – 11–32%, for potassium – 13–41%; in row crops for nitrogen is 42–93%, for phosphorus – 6–40%, for potassium – 13-110%; in forage crops for nitrogen is 85-89%, for phosphorus – 7–12%, for potassium – 17–23%. The current nitrification rate for grain crops was from 40 kg/ha on meadow-chernozem solonets to 79 kg/ha on common chernozem; for row crops - from 39 kg/ha on meadow–chernozem solonets to 114 kg/ha on meadow-chernozem soil; for forage crops – from 23 kg/ha on meadow-chernozem solonets to 37 kg/ha on meadow-chernozem soil. The least amount of it was formed on saline soil. The consumption of nitrogen, phosphorus and potassium by plants to obtain a unit of product weight is: grain crops – 43, 14 and 25 kg/ton; row crops – 4, 1.5, 7; forage crops – 11, 3, 23 kg/ton. The normative indicators defined in the research can be used to calculate fertilizer doses on forest-steppe soils and the balance of elements in crop rotation.