Botanical composition and productivity of drought-resistant grass mixtures based on crested wheat-grass for improving steppe meadows in the middle Lena River valley

Abstract

For the first time, the effect of compound fertilizers on the botanical composition, linear height of the grass stand, and productivity of non-irrigated drought-resistant meadow mixed grass crops for the improvement of steppe meadows was studied under the conditions of natural moisture and cryogenic soils of the Nam agricultural landscape in the middle taiga subzone of Yakutia. The linear growth of the Modun crested wheat-grass variety was stable at a height of up to 54 cm. The mixed cereal grass crops consisting of high-growing varieties exceeded the control by 9.6 cm or 17%, while the mixtures with alfalfa went beyond the control by 12.6 cm or 23% which indicated the comfort of plant growth in the cryogenic soils of Yakutia. In the cereal grass mixture, the highest survival rate was observed in the dominant crested wheat-grass variety Modun (59.1% of dry matter), while the involvement of awnless brome was up to 29.1% of dry matter and Siberian wildrye - 10.3% of dry matter; the hay yield decreased to 2.70 t ha which was by 15% lower than that of the control. The most efficient drought-resistant vetch-grass mixture consisting of crested wheat-grass up to 39.4% of dry matter, awnless brome - up to 26.7% of dry matter, and yellow alfalfa - up to 32.3% of dry matter, produced an average hay yield of up to 3.23 t ha with increased productivity in terms of metabolizable energy up to 32.76 GJ, fodder units - up to 2410, and crude protein - up to 0.461 t per ha. The energy nutritional value of the grass mixture of crested wheat-grass, awnless brome and yellow alfalfa was increased regarding the content of metabolizable energy in 1 kg of dry matter to 9.6 MJ and digestible protein in fodder units to 128 g which corresponded to first-class hay according to GOST 54452-2021.