To evaluate the effects of intercropping arrangements on phosphorus use efficiency and interspecific competition in legume-grass mixtures， same-row intercropping （T） and alternate-row intercropping （Y） was conducted by the pot experiment. The study investigated the relationships among phosphorus use efficiency （PUE）， interspecific competition， and the overyielding effect in triticale-hairy vetch and triticale-common vetch systems. The results showed that for the triticale-hairy vetch mixture， yield and overyielding were higher in the same-row arrangement， whereas the triticale-common vetch mixture was the opposite. The relative yield （RY） was higher in the alternate-row arrangement for both systems. Metrics including encroachment rate （A）， competition rate （CR）， and relative crowding rate （K） indicated that triticale was the competitively dominant species. Phosphorus use efficiency varied in the triticale-hairy vetch system， and it was higher for triticale under alternate-row but higher for hairy vetch under same-row intercropping； in the triticale-common vetch system， both species showed higher PUE in the alternate-row arrangement. Threshold analysis revealed that highly competitive ability coupled with high PUE synergistically induced the overyielding effect under the alternate-row arrangement. In conclusion， for establishing annual forages in the cool region of Zhaosu， the alternate-row intercropping of triticale and common vetch is recommended.

Legume-grass intercropping  /  Interspecific competition  /  Phosphorus use efficiency  /  Overyielding effect