TY JOUR TI VALUE OF PREDECESSOR IN THE CONDITIONS OF INTENSIFICATION OF GRAIN PRODUCTION OF THE REPUBLIC OF TATARSTAN KW crop rotation KW winter rye KW pure fallows KW occupied fallows KW productivity JO Vestnik of Kazan State Agrarian University AU Minikaev, R.V. AU Fatihov, D.A. PY 2020 IS 14 PB Kazan state agrarian University