TY JOUR TI EFFICIENCY OF SULFUR BENTONITE AND AMMONIUM SULFATE IN THE NUTRITION SYSTEM OF SUNFLOWER HYBRIDS ON TYPICAL GRAY FOREST SOILS OF THE REPUBLIC OF TATARSTAN KW sunflower KW sulfur KW sulfur bentonite KW ammonium sulfate KW nitrogen-phosphorus-potassium background KW gray forest soils KW yield KW hybrid. JO Agrobiotechnologies and digital farming AU Tahaviev, I.D. PY 2026 IS 5 PB Kazan state agrarian University