Nature and Strength of the Correlation between Spring Wheat Yield and Soil Factors under Grey Forest Soil Conditions
摘要
This study aimed to evaluate the relationship between the yield of spring soft wheat and the primary agrochemical indicators, as well as the spring reserves of plant-available moisture in the 1-m soil layer of gray forest soil. The research took place between 1982 and 2018 in the Pre-Kama region of the Republic of Tatarstan. Spring wheat was cultivated as part of a crop rotation sequence that included clean fallow, winter rye, and spring wheat. Each year, mineral fertilizers were applied to the preceding crop at the average recommended rates (N40–60, P40–50, K40–60), while no fertilizers were applied directly to the wheat crop. The soil of the experimental plot was classified as medium loamy gray forest soil, with the following agrochemical properties: organic matter content ranging from 2.8 to 3.2%, hydrolyzable nitrogen content from 100 to 149 mg/kg, mobile phosphorus and potassium content (according to the Kirsanov method) ranging from 105 to 184 mg/kg and 79 to 149 mg/kg, respectively, and pH of the saline soil extract ranging from 5.6 to 5.7. The yield of spring wheat grown without fertilizer application varied significantly across the years, ranging from 0.99 to 2.97 t/ha. The availability of macronutrients (NPK) in plant-accessible forms in gray forest soil accounted for 62% of the variation in yield. The optimal nutrient levels for achieving the highest grain yield in this experiment without fertilizer application were identified as 150 mg/kg of hydrolyzable nitrogen, 150 mg/kg of mobile phosphorus, and 140 mg/kg of mobile potassium.