Effects of nitrogen fertilizer levels on the production and nutritive value of forage rye in the Lhasa Dagzê District

The effects of different nitrogen fertilizers on the production and nutritive value of forage rye in the Lhasa Dagzê District were investigated using ‘Dongmu 70’ forage rye (Secale cereale). Five pure nitrogen fertilizing levels (0, 75, 150, 225 and 300 kg·ha⁻¹ , designated as N₀, N₇₅, N₁₅₀, N₂₂₅, and N₃₀₀, respectively) were set up, and the plant height, number of branches, fresh yield, hay yield,and nutritive value of the forage rye were measured for two consecutive years. The results showed that the application of nitrogen fertilizers could significantly increase the production and nutritive value of the forage, the forage rye had the best performance with the 225 kg·ha⁻¹ nitrogen treatment, and the dry yield can reach up to 9898.33 and 9390.14 kg·ha⁻¹ in 2020 and 2021, respectively. The important nutritive value evaluation indexes, such as crude protein, ether extract, starch, neutral detergent fiber, and the acid detergent fiber of forage grass were improved with the increase in nitrogen levels. Thus, from the forage production and nutritional value considerations, the recommended nitrogen fertilizer levels for forage grass farmland in the Lhasa Dagzê District are 225 kg·ha⁻¹.