Nitrous oxide (N2O) is an effective ozone-depleting substance and an important greenhouse gas in the atmosphere. Fertilization is a major factor that dictates agricultural N2O emissions. In this work, as opposed to the commonly-seen highly-soluble N-fertilizers, we determine the feasibility of using struvite as a slow-releasing N-fertilizer and investigate its mechanism for mitigating N2O emissions. During the 149-d field cultivation of water spinach (Ipomoea Aquatica Forsk), struvite exhibits comparable crop yields, with a 40.8-58.1% N2O reduction compared with commercial fertilizers. In addition, we observe that struvite increases soil bacterial diversity effectively, while decreasing the level of nitrification genes (amoA) and increasing the content of denitrification genes (narG, nirS, nirK, norB and nosZ). By conducting partial least-square path modeling, we find that struvite mitigated N2O emissions by limiting the free ammonia-nitrogen and increasing the soil pH. Moreover, using struvite as the N-fertilizer may increase the struvite price from 50 to 131.7 €/ton, which creates added values for struvite-based P-recovery technologies. These findings provide new insights for effectively mitigating the agriculture N2O emission and help change the inherent impression that struvite is only suitable as a phosphorus (P) fertilizer, which could also benefit the struvite-based P-recovery technologies.
