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.