Effects of fermented organic fertilizer application on soil N2O emission under the vegetable rotation in polyhouse

Vegetable field is one of the main sources of soil nitrous oxide (N2O) emission, yet soil N2O emission from vegetable rotation with combined application of fermented organic fertilizer with inorganic fertilizer in polyhouse is not well evaluated. In this study, we investigated the soil N2O emission in cabbage-tomato rotation management system under different treatments of fertilizer nitrogen (N) sources, including: 100% inorganic fertilizer (IF), 75% IF+25% fermented organic fertilizer (OF), 50% IF+50% OF, 75% IF+25% OF, 100% OF, and no fertilizer (CK). The fertilization amount of N was 180 kg ha-1 to cabbage and 200 kg ha-1 to tomato. Results showed that soil N2O emission flux was in a high level during 1-3 days after basal fertilization for cabbage, and decreased as the proportions of OF increased. During the whole cabbage-tomato rotated cultivation, N2O emission flux was positively related to soil NO3--N and NH4+-N contents, with correlation coefficients of 0.72 and 0.90, respectively. A higher proportion of OF increased the soil total carbon (C), organic C and C/N ratio, but decreased the soil nitrifiers and denitrifiers. The fertilizer N loss caused by N2O emission under different OF treatments was 1.23-2.77%, significantly (p < 0.05) lower than under 100% IF treatment (3.58%), and the loss decreased with the increase of OF proportion. Our study quantitatively revealed the N2O emission under vegetable rotation systems with different fertilizations in polyhouses, and the overall results suggested that the higher soil pH, the lower soil mineral NO3--N and NH4+-N as well as lower soil nitrifiers and denitrifiers contributed to less N2O emission for the OF treatments