TY JOUR TI DYNAMICS OF FERTILITY OF AGRICULTURAL CHERNOZEMS OF FOREST-STEPPE ZONE OF THE CENTRAL CHERNOZEM REGIONS OF RUSSIA KW phosphorus KW potassium KW fertilizers KW chernozem KW fertility KW acidity KW liming KW organic matter KW macro- and microelements JO Vestnik of Kazan State Agrarian University AU Surinov, A.V. PY 2021 IS 16 PB Kazan state agrarian University