Evaluation of productivity of different Vicia sativa cropping systems in the Lhasa area of Tibet, China

The dry matter yield, soil fertility, and economic output of different rotation systems of common vetch (Vicia sativa) were studied under field conditions in the Tibetan Plateau in the Lhasa region for two consecutive years. The treatments used in this study were fallow – Hordeum vulgare – fallow (F–H–F), rape (Brassica napus) – Hordeum vulgare – rape (R–H–R), common vetch – Hordeum vulgare – common vetch (V–H–V), common vetch – Hordeum vulgare – rape (V–H–R), and rape – common vetch – rape (R–V–R). The results showed that the highest yields were observed with V–H–R and R–H–R (27.24 and 26.89 t·ha^–1, respectively). There was a significant difference in total crude protein production between the rotation systems (P < 0.05), and the R–H–R system had the highest, at 3.68 t·ha^–1. The V–H–V and V–H–R systems with Lanjian No. 1 had higher average soil total N content than that of the F–H–F and R–H–R systems, which increased by 134.9%, 19.6%, 115.6%, and 9.8%, respectively. The differences in soil organic carbon content among the rotation systems were not significant. The systems with the highest economic output values were V–H–V and V–H–R, at 44 284 and 41 444 CNY·ha^–1, respectively. Therefore, spring common vetch provides excellent forage for relieving forage shortage in livestock husbandry of the Tibetan Plateau, and has great potential.