The balance of calcium and magnesium carbonates determines the change of acidity level in arable soils. It is required an adequate assessment of their removal with crop yields to calculate the balance of nutrient elements. The aim of the study is to investigate the effect of traditional fertilizer systems on two backgrounds of arable layer acidity on the content of calcium and magnesium in the green mass of vetch-oat mixture and to quantify the alienation of elements with yield from the soil. The main research method is long-term field experiment on sod-podzolic medium-cultivated soil. The peculiarity of the experiment was a long period of research (5 years) under different agroclimatic conditions. Dry matter yield increase from the decrease in soil acidity on average for 5 years amounted to 5%. Yield growth from fertilization systems for the same period of time ranged from 27 to 59% in relation to the variant without fertilization. On average in the experiment at dry matter yield of 6.7 t/ha, the total yield removal of calcium and magnesium from the soil was 79.8 kg/ha. The value of removal depended more on the fertilizer system than on the soil acidity background. Calcium and magnesium content in green mass of vetch-oat mixture changed more under the influence of fertilizer systems than depended on soil acidity background. On average, the content of CaO in the green mass was 0.83%, and MgO – 0.35% of dry matter (d.m.). According to the research results, we proposed the refined coefficient for calculating the calcium and magnesium removal from the soil by the hay crop of annual legume-grass grass mixtures grown in the Vologda Region, equal to 6.9 kg per 1 ton of conventional hay
Keywords
soil fertility, yield, vetch-oat mixture, calcium and magnesium removal, fertilizer system