TY JOUR TI MATHEMATICAL MODEL OF MINERAL NUTRITION OF SPRING WHEAT ON THE RESULTS OF LONG-TERM RESEARCH OF AGRARIAN UNIVERSITY OF NORTHERN URALS KW mathematical model KW regression statistics KW correlation coefficient KW approximation co-efficient KW statistical processing KW database KW planned productivity KW mineral fertilizers KW spring wheat KW leached chernozyom JO Bulletin of KSAU AU Eryomina, D.V. PY 2017 IS PB Krasnoyarsk State Agrarian University