Efficiency of nitrogen fertilizers and biological preparations for winter rye on soddy-podzolic soil of different cultivation status

There was studied the influence of soddy-podzolic light loamy soil of different cultivation status on the agronomic efficiency of mineral fertilizers application with varying doses of nitrogen and biological preparations applied against the mineral background, in Pskov region. On moderately cultivated soil the linear dependence of grain yield on nitrogen rates was established. An increase in nitrogen doses from 20 to 80 kg a. i./ha resulted in obtaining an additional yield compared to the control variant, which is dependent on soil pH: yield growth by 6% to 42% was recorded on soil with pH of 5.6; from 8% to 73% – on soil with pH of 5.3; from 32% to 69% – on soil with pH of 5.2; from 66% to 175% – on soil with pH of 4.8. Payback from applied fertilizers rose with increasing doses of nitrogen. Soil properties also influenced the payback value. The maximum payback, 12 kg of grain per 1 kg of NPK, was recorded when N 80 P 40 K 70 with split nitrogen fertilizing was applied to the soil with pH = 4.8. The introduction of biological products to the variant with mineral fertilizers (N 20 P 40 K 70 + N 20 ) contributed to an increase in grain yield : the introduction of microbiological preparation Bisolbifitis provided additional 7.55%; spraying of foliar fertilizers – 3.67%–8.78%. On the soil with long-term cultivation status the dependence of yield on the doses of applied nitrogen in the range from 20 to 80 kg a. i./ha looked like a polynomial. Maximum yield was obtained in different years when nitrogen was applied at rates from 40 and 60 kg a. i./ha. An increase in the dose of nitrogen from 20 to 40 kg was accompanied in 2019 by an increase in the yield of grain from 11.2% to 22.6%. An increase in nitrogen rates from 20 to 60 kg in 2020 and 2021 resulted in the growth of grain yield from 20% to 65%. Respectively. When the most effective doses of nitrogen were applied the payback from fertilizers was 5 kg of grain per 1 kg of NPK in 2019; 7 kg of grain per 1 kg of NPK in 2020; and 10 kg of grain per 1 kg of NPK in 2021. On the soil cultivated and improved for a long-term the effect of foliar fertilizers with biological preparations Kodamine B-Mo and K-Humate-Na was less significant (3–3.5%).