The forage yield, soil nutrients, and variation of soil nutrition were compared by monocultures of Avena sativa, Vicia sativa, Pisum arvense, and combination of A. sativa + V. sativa and A. sativa + P. arvense mixed patterns to explore the effects of soil amelioration while ensuring the performance of forage production in Maizhokunggar Sibu pasture of Tibet in 2019. The results showed that: (1) The hay yield of mixed sowing ratio of A. sativa∶V. sativa at 70%∶30%, and A. sativa∶P. arvense at 50%∶50% were the highest, which increased by 11.8% and 28.0% compared to monocultures of A. sativa, and increased by 24.5% and 17.4% compared to monocultures of A. sativa and P. arvense, respectively. (2) The crude protein (CP) of monocultures of V. sativa and P. arvense were 19.29% and 15.74%, respectively. The CP content of mixed sowing treatments showed a decreasing trend with increasing A. sativa sowing ratio, and the highest decreasing amplitude was 54.48% and 57.12%, respectively; while the neutral detergent fiber (NDF) and acid detergent fiber (ADF) showed the opposite trend. (3) The content of soil organic matter, total nitrogen (N), alkali-decomposed N, available phosphate (P), and available potassium (K) of monocultures of A. sativa were reduced by 1.10, 0.03 g·kg-1, and 22.93, 3.27, 4.38 mg·kg-1, respectively, compared with that in the monocultures of A. sativa. Increasing sowing rate of legume effectively improved the soil nutrients. The content of soil organic matter, total N, alkali-decomposed N, and available P were increased by 4.5%, 9.1%, 3.6%, and 6.1%, respectively, which improved the supply of available nutrients such as alkali-decomposed N and available P. In summary, grass-legume mixture is beneficial to the purpose of increasing forage production and conservation of cultivated land. |