This study aimed to investigate the interspecific nutrient competition characteristics and their effects on the productive performance of an oat （Avena sativa L.） and forage pea （Pisum sativum L.） system under different intercropping ratios in Corral lands of the Qinghai alpine region. A field experiment was conducted in Haiyan County， Qinghai Province， from 2023 to 2024， with treatments including Avena sativa∶Pisum sativum intercropping ratios of 2∶1 （O2P）， 1∶1 （OP）， and 1∶2 （OP2）， as well as monocropping oat （MO） and monocropping pea （MP） as controls. Measurements included dry matter yield， plant height， leaf area， stem-to-leaf ratio， contents and accumulations of nitrogen （N）， phosphorus （P）， and potassium （K）. The land equivalent ratio （LER） and competition rate （CR） were calculated. The results showed that： （1） The LER values under all intercropping ratios were greater than 1， with the OP treatment exhibiting the highest value， indicating that intercropping provided an advantage in land resource utilization； （2） The yield CR of oat was consistently greater than 1， demonstrating that intraspecific competition predominated， whereas the CR of pea was less than 1， indicating stronger interspecific competition； （3） Oat exhibited stronger competitive ability for N and P than pea across all intercropping ratios， while competition for K varied with the ratio-pea outperformed oat only under the OP2 ratio； （4） The OP treatment achieved the highest dry matter yield， despite oat individual leaf area being the lowest in this treatment， suggesting that the high system productivity relied primarily on interspecific functional complementarity and population synergy rather than individual morphological advantages. In conclusion， oat/pea intercropping enhances system productivity through resource complementarity and competition coordination， with the 1∶1 intercropping ratio being a suitable model for forage production in alpine Corral lands.

Oats  /  Peas  /  Mixed cropping  /  Nutrient competition