THE NATURE AND STRENGTH OF THE CORRELATION OF SPRING WHEAT YIELD WITH SOIL FACTORS IN CONDITIONS OF GRAY FOREST SOIL

The study was carried out in order to assess the dependence of the yield of spring soft wheat on the main agrochemical indicators and spring reserves of productive moisture in a meter layer of gray forest soil. The work was carried out in 1982-2018. in the Kama zone of the Republic of Tatarstan. Spring wheat was cultivated in the crop rotation link: pure fallow - winter rye - spring wheat. Under the predecessor, the average recommended norms of mineral fertilizers (N40 ... 60P40 ... 50K40 ... 60) were annually introduced; fertilizers were not applied directly under the wheat. The soil of the experimental plot is gray forest medium loamy with the following agrochemical parameters: organic matter content - 2.8 ... 3.2%, easily hydrolyzable nitrogen - 100 ... 149 mg / kg, mobile phosphorus and potassium (according to Kirsanov). ) - 105...184 and 79...149 mg/kg, respectively, pHrast. – 5.6...5.7. The yield of spring wheat cultivated without fertilization varied greatly over the years and ranged from 0.99 to 2.97 t/ha. It amounted to 62% due to the influence of the provision of gray forest soil with the main nutrient macronutrients (NMC) in a form available to plants. The content of readily hydrolysable nitrogen 150 mg/kg, mobile forms of phosphorus and potassium 150 and 140 mg/kg, respectively, turned out to be the optimal level for the formation of the largest grain yield of spring wheat in the experiment on gray forest soil. without the use of fertilizers.