Annotation It is shown that the buffer capacity of dry matter of alfalfa of the first cut in the flowering phase is 5.66-5.94 mol / liter. With an increase in the content of crude protein and crude ash by 1%, it increases by 0.14-0.40 and 0.49-0.86 mol / liter, respectively, with an increase in the content of soluble carbohydrates by 1%, it decreases by 1.44 mol / liter … The dry matter of the second cut alfalfa has a high forage quality. The content of crude protein from the stemming-beginning of budding phase to the flowering phase is in the range of 23.44-20.20%, crude ash 9.24-8.10%, while the content of crude fiber is reduced to 22.92-29.01%, dry matter - up to 20.84-26.00%. The buffer capacity of dry matter reaches 9.69-7.23 mol / liter. The main influence on the buffer capacity is exerted by the mineral composition of the dry matter. An increase in the content of crude ash by 1% increases the buffer capacity of dry matter by 0.55 ± 0.16 - 1.36 ± 0.14 mol / l, an increase in the content of crude protein by 1% increases the buffer capacity by 0.15 ± 0.06 - 0.39 ± 0.14 mol / liter.