Drip Irrigation in Dryland Agriculture Controls Soil Water-Filled Pore Space and Reduces Greenhouse Gas Emissions: A Meta-Analysis

Drip irrigation (DI) could effectively reduce greenhouse gas (GHG) emissions from dryland agriculture, helping mitigate global warming. Here, we performed a meta-analysis to quantify the effects of dryland DI on GHG emissions under different climatic conditions, soil conditions, and agricultural management practices. The results showed that DI can reduce GHG emissions by decreasing the soil moisture content (i.e., water-filled pore space). The N₂O and CO₂ emissions decreased by 29.2% and 6.1%, respectively, and global warming potential decreased by 18.7%, but CH₄ emissions increased by 9.7%–14.0%. When the irrigation scheduling was higher than 70% and the nitrogen application was 180–300 kg ha⁻¹, shallow buried DI with water flow controlled below 2 L hr⁻¹ was the best strategy for emission reduction. In addition, compared with traditional irrigation methods, DI demonstrates greater long-term effectiveness in reducing N₂O and CO₂ emissions. We also found that greenhouse vegetable production combined with DI has great potential for reducing GHG emissions. This study provides evidence for the application of DI technology to reduce global dryland GHG emissions.