Effect of different sowing patterns on production performance and soil nutrients in Avena sativa + Vicia sativa mixtures

The productivity performance of legume–grass mixtures was analyzed by comparing forage yield, forage nutrients, seed yield, and soil nutrients inVicia sativa + Avena sativa mixtures with different sowing patterns (mixed cropping, intercropping, and different mix ratios). The effects of sowing pattern on the relationships between soil nutrient characteristics, productivity performance, and the advantages of mixed sowing were discussed. The results showed that 1) V. sativa + A. sativa mixtures can gain advantages from mixed sowing. The legume : grass mix ratios of 50 : 50 with mixed cropping, 50 : 50 with intercropping, and 75 : 25 with mixed cropping all displayed obvious advantages in forage yield and seed yield. 2) Mixed sowing patterns had little effect on soil organic matter or soil total nutrient content. Monocultures of A. sativa had higher soil available phosphorus contents. The biological nitrogen fixation of V. sativa increased the supply of soil nitrogen, and mixed cropping is therefore beneficial for the accumulation of soil alkali nitrogen. 3) When a mixed community structure was used as a control factor, forage yield and crude protein yield were dependent on soil nitrogen nutrition and negatively correlated with soil available phosphorus. When a mixed, high V. sativa ratio (80% and 100%) was used as a control factor, soil nitrogen nutrition negatively affected forage yield, crude protein yield, and forage yield advantage. At lower ratios the relationships were positive. Soil available phosphorus negatively affected forage yield, crude protein yield, and yield advantage, but positively affected grain yield advantage, and showed no correlation with mixed planting proportion. In conclusion, A. sativa + V. sativa mixtures with a legume : grass mix ratio of 75 : 25 with a mixed cropping pattern conferred higher mixed advantages in these cool climate pastoral areas. The mixed pattern could not only improve soil fertility, but also increase harvest forage yield and improve the quality of grass products.