Ridge and furrow rainfall harvesting can significantly reduce N2O emissions from spring maize fields in semiarid regions of China

Abstract The ridge and furrow rainfall harvesting (RFRH) system is an effective method for enhancing the rainfall water use efficiency and crop yield. Determining how the fertilization rate affects soil nitrous oxide (N2O) emissions under the RFRH system has important practical significance for improving fertilization strategies and evaluating the environmental effects of the RFRH system. Therefore, we conducted a three-year field experiment in the Loess Plateau, China, to compare the RFRH system with traditional flat planting (T) at four different fertilizer rates (no fertilizer, N:P2O5 at 150:75 kg ha–1, N:P2O5 at 300:150 kg ha–1, and N:P2O5 at 450:225 kg ha–1). Under the same fertilization level, the soil water content (SWC) and dry matter were higher under RFRH compared with T, and the nitrate nitrogen (NO3−-N) content and N2O emissions were reduced. In the two planting models, SWC and NO3−-N of each treatment and its corresponding N2O emission flux were significantly positively correlated. Under the same planting model, SWC decreased but NO3−-N and the N2O emission increased with increasing fertilization rate. SWC was the key variable affecting the N2O emission flux in the RFRH system. In addition, the grain yield under RFRH increased by 2.2–28.0%, whereas the global warming potential (GWP) and greenhouse gas intensity (GHGI) decreased by 1.0–16.1% and 13.0–56.8%, respectively, compared with T. The grain yield and GHGI had quadratic relationships with the fertilization rate. Moreover, GWP increased in a linear manner with the fertilizer rate. These findings suggest that the RFRH system is an effective tillage measure for reducing N2O emissions. When the N:P2O5 fertilization rate was 200:100 to 307:154 kg ha−1, the RFRH system could maintain a higher grain yield and reduce the N2O emissions.