Features of enzymatic activity of soils in agricultural landscapes of the Vladimir high plains

The research aimed to study the enzymatic activity of grey forest soil (GF) and grey forest soil with a second humic horizon (GF SHH) depending on fertilizer systems in agricultural landscapes in the Vladimir region. The work was carried out in 2021–2023 in a stationary field experiment on two soil varieties. The following backgrounds for intensifying the use of fertilizers were studied (for rotation of a 6-field crop rotation): zero (Z) – manure 40 t/ha; intensive (I) – manure 40 t/ha + N₁₀₀Р₈₀К₁₆₀; intense mineral (IM) – N₃₅₀P₂₂₀K₃₉₀; high-intensity mineral (HIM) – N₄₈₀P₂₈₀K₅₇₅; intensive organomineral (IOM) – N₃₁₀P₁₅₀K₃₁₀ + manure 60 t/ha; high-intensity organomineral (VIOM) – N₄₃₀P₁₆₀K₃₆₀ + manure 80 t/ha. Against the studied backgrounds of fertilizer use in the GF SHH, a stable trend of increasing the activity of catalase and invertase was revealed. The average activity of catalase in the soil of the second humus horizon was 23 % higher than in the GF, at the same depth (20–40 cm). The maximum catalase activity in the experiment was observed against an intense background (I) in the GF SHH: layer 0–20 cm – 2.41 ml O₂/g; 20–40 cm – 1.96 ml O₂/g. Invertase activity in soil with a second humus horizon at a depth of 20–40 cm is on average 30 % higher than in grey forest soil. The highest value of this indicator was observed in the soil of two soil phases against an intense background in the 0–20 cm layer – 3.50–3.55 mg of glucose/g in 40 hours. The average humus content in the second humus horizon GF SHH was at level 3,76 %, which was 33 % higher than in GF in a layer of 20–40 cm. The maximum value of this indicator in the experiment (layer 0–40 cm) was observed in GF SHH against the intensive background of fertilizer use – 4.86 %.