An experiment was carried out in a greenhouse, with the surface layer of a clayey Red Yellow Latosol placed in plastic pots. A 4x3x4 factorial was used. Lime rates (0; 380; 760 and 1140 mg kg-1 of soil) and potassium rates (0; 40 and 120 mg kg-1 of soil) and alfalfa cultivars (Crioula, Moapa, Florida77 and CUF101) were studied. A randomized complete block design, with four replications, was used. Plants were harvested 70 days after sowing and allowed to regrow. A second harvest was done between 34 to 41 days after the first one. Florida77 and CUF101 cultivars had the highest dry matter yield at the first harvest, but all the cultivars had similar yields at the second harvest. Maximum DM yield and total amount of nitrogen were estimated to occur with dolomitic limestone rate between 886 and 1095 mg kg-1 (soil base saturation between 64.8 and 68.6%), whereas for potassium they were estimated between 44.7 and 74.2 mg kg-1 . Visual symptoms of potassium deficiency were observed in plants grown in the soil that did not receive potassium fertilization.
liming; potassium; nitrogen; alfalfa; Medicago sativa L.