Nitrogen fertilizer and nitrapyrin for greenhouse gas reduction in wolfberry orchards on the Qinghai–Tibetan Plateau

Abstract

Wolfberry production has become a major agro-industry on the Qinghai–Tibetan Plateau, causing increased nitrogen (N) pollution and greenhouse gas (GHG) emissions. Appropriate N fertilizer rate and nitrification inhibitors may mitigate GHG emissions and improve N use efficiency. A 2-year field experiment was conducted to measure the effects of N application rate and nitrapyrin on GHG emissions, to reduce GHG emissions and N pollution. We used eight treatments: Control (CK), 667 kg·ha‾¹ N (Con), 400 kg·ha‾¹ N (N₄₀₀), 267 kg·ha‾¹ N (N₂₆₇), 133 kg·ha‾¹ N (N₁₃₃), 400 kg·ha‾¹ N plus 2.00 kg·ha‾¹ nitrapyrin (N₄₀₀I₂.₀₀), 267 kg·ha‾¹ N plus 1.33 kg·ha‾¹ nitrapyrin (N₂₆₇I₁.₃₃) and 133 kg·ha‾¹ N plus 0.67 kg·ha‾¹ nitrapyrin (N₁₃₃I₀.₆₇). Compared with Con treatment, N₄₀₀ maintained fruit yield and increased net income, but saved 40% of N fertilizer and decreased the cumulative N₂O emission by 14–16%. Compared to N₄₀₀, N₂₆₇ and N₁₃₃ treatments, the cumulative N₂O emission of N₄₀₀I₂.₀₀, N₂₆₇I₁.₃₃ and N₁₃₃I₀.₆₇ treatments was reduced by 28.5–45.1%, 26.6–29.9% and 33.8–45.9%, respectively. Furthermore, N₄₀₀I₂.₀₀ resulted in the highest wolfberry yield and net income. The emissions of CH₄ and CO₂ were not significantly different among treatments. Moreover, the global warming potential (GWP) and the greenhouse gas emission intensity (GHGI) of N₄₀₀I₂.₀₀ declined by 45.6% and 48.6% compared to Con treatment. Therefore, 400 kg·ha‾¹ N combined with 2.00 kg·ha‾¹ nitrapyrin was shown to be a promising management technique for maintaining wolfberry yield while minimizing GWP and GHGI.