Changes in photosynthetic activity of perennial grasses depending on soil treatment and fertilizers

Perennial grasses are the main source of animal feed. They have important agronomic and ecological significance. High and stable yields are achieved by creating crops with ideal characteristics of the leaf surface, high net productivity of photosynthetic processes, maximum photosynthetic potential and efficient work of the assimilating surface, which ultimately ensures the planned harvest volume is obtained. The article presents the results of the studies of moldboard, surface-moldboard and surface cultivation systems, as well as straw-based fertilization systems both separately and in combination with complete mineral fertilization. Data are provided on the leaf area, dry matter accumulation, photosynthetic potential and net productivity of photosynthetic processes, as well as the yield of perennial grasses on average for 2023–2024. The studies were carried out on sod-podzolic gleyic medium loamy soils of the Yaroslavl region. During the experiments, the use of resource-saving soil cultivation systems contributed to a decrease in the photosynthetic indices of red clover and timothy grass. This can be explained by the suppression of cultivated plants by weeds with minimal soil cultivation. The use of a full rate of mineral fertilizers both separately and together with straw caused an increase in the leaf area, accumulation of dry matter and photosynthetic potential of the above-mentioned crops with maximum values for the SNPK background. The highest yield of green mass of perennial grasses was noted with the surface-moldboard cultivation system in the variant of combined use of straw and a full rate of mineral fertilizers. On average, over the years of research, the indicator was noted at the level of 218–226 c/ha.