TY JOUR TI RESULTS OF FIELD STUDIES OF SOIL-TILLAGE TOOLS WITH ELLIPSOVID DISKS KW tillage KW elliptical disks KW rotary tool KW ridging KW soil crumbling KW depth of processing JO Vestnik of Kazan State Agrarian University AU Yarullin , F.. AU Ibyatov, R.. AU Yakhin, S.M. AU Gaynutdinov, R.H. PY 2019 IS 14 PB Kazan state agrarian University