Research has shown that extending the vegetation period of winter rye grown for green manure until the third ten-day period of May results in the highest yield of green biomass – 40 t ha-1 and, accordingly, the greatest accumulation of sequestered atmospheric carbon – 4.32 t ha-1. However, with this incorporation date, the highest soil bulk density and hardness were recorded in the root zone during buckwheat cultivation. The lowest bulk density in the 0–30 cm soil layer was achieved when the green manure was incorporated in the second ten-day period of May – 1.14 g/cm³ at the time of sowing and 1.16 g/cm³ at flowering. Incorporation in the same period also resulted in the lowest soil hardness: 13.8 kg/cm² at sowing and 16.0 kg/cm² at flowering. Incorporating the green manure no later than 10 days before buckwheat sowing led to the highest reserves of productive moisture in the 0–10 cm topsoil layer – 12.2–12.4 mm. At flowering, the best moisture reserves in the 0–30 cm layer were observed after incorporation in the second ten-day period of May – 35.2 mm. The most favorable soil agrophysical parameters contributed to the highest buckwheat yield – 2.72 t ha-1 when winter rye was incorporated in the second ten-day period of May. The use of winter rye as green manure enriches the soil with organic matter and helps sequester carbon from the atmosphere by utilizing natural resources. This winter crop also protects soil from water and wind erosion, promotes biological loosening, and supports the activity of soil biota due to active root function. Incorporating green manure into the soil 10 days before buckwheat sowing allows achieving an optimal balance: obtaining the maximum amount of green biomass without significant loss of soil moisture. This is critical for successful germination of the organic buckwheat crop and for loosening the soil.