Development of High-Yield Forage Agrocenoses for Sustainable Livestock Production in Northern Kazakhstan

Low forage productivity of natural grasslands remains a major limitation for sustainable livestock production in the forest–steppe zone of Northern Kazakhstan, highlighting the need for high-yield, locally adapted forage systems. This study evaluated nine forage agrophytocenoses, including perennial grasses and legume–grass mixtures, established in 2024 and assessed over two growing seasons on leached chernozem soils. Plant height, stand density, and biomass yields were quantified at optimal harvest stages, with statistical differences tested using one-way ANOVA and Tukey’s HSD (p < 0.05). Legume-containing agrophytocenoses consistently outperformed natural grass cover and grass monocultures in canopy development and biomass accumulation. The highest productivity was achieved in Lolium multiflorum + Medicago sativa (I+A), Medicago sativa + Festuca arundinacea (A+TF), and Onobrychis viciifolia + Festulolium + Phleum pratense (S+F+T), reaching up to ~19.66 t ha−1 green biomass and ~5.24 t ha−1 dry matter. In contrast, Agropyron cristatum monoculture yielded minimally during establishment, while ryegrass mixtures with annuals declined in the second year. Optimized legume–grass agrophytocenoses represent the most productive and agronomically reliable strategy to enhance forage supply and improve environmental resilience in Northern Kazakhstan.