Effects of utilization modes, planting patterns, and nitrogen applications on the yield and quality of perennial forage

The objective of this study was to explore the effects of planting patterns and nitrogen applications on forage yield and quality under different utilization modes. Therefore, we applied grazing (G) and mowing (M) treatments on cultivated grasslands in Huan County, Gansu Province. For each utilization mode, there were three planting patterns (W: monoculture of Bromus inermis; H: monoculture of Onobrychis viciifolia; and WH: mixed planting of the two forages) and three nitrogen application levels (N₁: 0; N₂: 80 kg·ha⁻¹; and N₃: 160 kg·ha⁻¹). The results showed that 1) Compared to the M treatment, the G treatment significantly increased the total fresh and hay yields and significantly decreased the crude fat, neutral detergent fiber (NDF), and acid detergent fiber (ADF) content, thus increasing the relative feeding value (RFV). 2) Compared to the W planting pattern, the WH and H planting patterns significantly increased the total fresh and hay yields, with WH significantly higher than H, and significantly increased the crude protein and crude fat content, significantly reducing the NDF content, and significantly increasing the RFV. 3) The total fresh and hay yields increased significantly with the increase in nitrogen application, and the crude protein and crude fat content of the N₂ and N₃ treatments were significantly higher than those of N₁, whereas the NDF and ADF content were significantly lower than those of N₁, and RFV was significantly higher than that of N₁. Therefore, the planting pattern of mixed grassland of B. inermis and O. viciifolia and nitrogen application of 160 kg·ha⁻¹ are suitable management strategies for the cultivated grazing grassland in East Gansu.