Effect of mineral fertilization and soil cultivation practices on root mass accumulation of alfalfa was studied. Field trial was conducted in the Institute of Forage Crops, Pleven, Bulgaria on leached chernozem subsoil type and no irrigation. The next treatments were tested: (1) For fertilization as follows: N0P0K0 (control), N60P100K80 (an accepted technology), N23P100K35 (nitrogen was applied 1/2 in first year of growing, 1/2 in third year), N23P100K35 (nitrogen was supplied pre-sowing), N35P80K50 and Аmophose, calculated at fertilizing rates N27P120K0 and (2) For soil cultivation as follows: soil loosing 10-12 cm, plough at depth 12-15 and 22-24 cm (an accepted technology), 18-22 and 30-35 cm. It was found that alfalfa plants accumulated the biggest amount of dry root mass (4550 kg haG 1) at the plough at the depth of 18-22 and fertilization at N35P80K50. Supplying of plants with an initial amount of nitrogen was essential for the root mass formation in shallow soil cultivation practices. Both, mineral fertilization and soil cultivation had effect on root mass accumulation of alfalfa.