Effects of Irrigation Methods on Greenhouse Gas Emissions from Arid Farmlands: A Meta-analysis

Abstract

【Objective】 Irrigation methods modulate soil water and root-induced activity thereby influencing gas emissions from soil. In this paper, we analyze the effects of different irrigation methods on greenhouse gas emissions from farmland and the associated underlying mechanisms. 【Method】 The analysis was based on meta-analysis. Experimental results published in journals included in CNKI and Web of Science were used in the analysis. A total of 37 papers with 176 datasets were analyzed to assess the variation in greenhouse gas emissions with irrigation methods, as well as the underlying mechanisms. 【Result】 Compared to drip irrigation, flood irrigation, furrow irrigation and subsurface drip irrigation did not show significant difference in CO2 emissions, while sprinkler irrigation significantly increased CO2 emissions (p<0.05). Flood irrigation, furrow irrigation and sprinkler irrigation increased N2O emissions (p<0.05), but no significant difference between subsurface drip irrigation and drip irrigation was found in N2O emissions. There was no significant difference in CH4 emissions between different irrigation methods. In furrow irrigation, soil temperature was the key factor influencing CO2 emissions. Soil NH4+, temperature, and soil water-filled pore space (WFPS) were the key factors affecting N2O emissions. Soil NO3- played a pivotal role in CO2 emissions in flood irrigation, while soil NH4+, temperature, and soil water content influenced N2O emissions most. Sprinkler irrigation predominantly influenced soil WFPS and hence N2O emissions. Subsurface drip irrigation impacted soil temperature and hence CO2 emissions; soil NO3- and WFPS combined influencing N2O emissions. Drip irrigation influenced soil NO3- and NH4+, WFPS and soil temperature, thereby affecting CO2 and N2O emissions. 【Conclusion】 Replacing sprinkler irrigation and traditional flood irrigation and furrow irrigation by drip irrigation in arid regions can reduce greenhouse gas emissions from soils.

Keywords

• irrigation method
• soil water distribution
• greenhouse gas emission
• meta-analysis