Response of Soil N 2 O emissions to soil microbe and enzyme activities with aeration at two irrigation levels in greenhouse tomato (Lycopersicon esculentum Mill.) fields

Abstract

Aerated irrigation is proven to increase soil N 2 O emissions; however, the mechanisms of N 2 O release are still unknown. A field experiment for two consecutive greenhouse tomato-growing seasons, from August 2016 to July 2017, was carried out to examine (1) the differences of aeration and irrigation on soil N 2 O emissions with a static chamber GC technique, and on soil physical and biotic parameters, and (2) the response of soil N 2 O emissions to soil physical and biotic parameters. Two irrigation levels were included: 60% (low irrigation) and 100% (high irrigation) of the full irrigation amount. Each irrigation level contained aeration and control, totaling four treatments. During the two growing seasons, soil N 2 O emissions with aeration were 4.5% higher than the control (p > 0.05). Soil N 2 O emissions under the high irrigation were 13.8% greater than under the low irrigation, and the difference was significant in 2017 (p < 0.05). Aeration and irrigation had positive effects on the mean soil nitrifier abundance and mean soil urease activity, and the impact of irrigation on urease was significant in 2016 (p = 0.001). In addition, aeration negatively influenced the mean soil denitrifier abundance, while irrigation positively influenced the mean soil denitrifier abundance. Regression analysis showed that the soil water-filled pore space, temperature, and denitrifier abundance were primary factors influencing soil N 2 O fluxes. This study provides a further understanding of the processes affecting soil N 2 O emissions and N dynamics, which may assist in developing mitigation strategies to reduce N 2 O emissions.