Evaluation of mixed sowing methods for oats and vetch under drip irrigation in arid areas of Ningxia

In this study, with a view toward improving forage supply capacity, we sought to determine the best mixed sowing method for oats and vetch in arid areas of Ningxia. The study was based on a single-factor randomized block design, and we examined the effects of mixed sowing (inter-row mixed sowing, cross-mixed sowing, strip mixed sowing, oat single sowing, and single sowing) on the agronomic traits, interspecific relationships, and nutritional quality of forage grass under drip irrigation conditions. Comprehensive evaluations were performed using principal component analysis (PCA). The results obtained revealed that the four mixed sowing methods for oats and vetch significantly increased forage yield and improved forage quality (P < 0.05). The output of forage hay reached 11 164.47 kg·ha⁻¹, which is 50.76% and 47.94% higher than that of oats and vetch, respectively. Furthermore, the total relative yields of the four mixed sowing methods were all greater than 1, thereby indicating that intraspecific competition is stronger than interspecific competition. Oats and vetch were found to show a certain niche differentiation. The relative feeding value of interline mixed pasture was 124.38, which was lower only than that of unicast vetch. The findings of PCA analysis revealed that the performance of mixed forage inter-planting with oats and vetch ranked highest. Therefore, we recommend that the inter-row mixed sowing of oats and vetch should be promoted and applied under drip irrigation conditions in the arid regions of Ningxia.