Irrigation is a common practice used to promote vegetable yields through high agricultural inputs, which potentially increases nitrous oxide (N2O) emissions. However, it is still unclear how an effective irrigation strategy could increase yield by regulating soil water conditions, ultimately mitigating N2O emissions.
In this study, negative pressure irrigation (NPI) and furrow irrigation (FI) were applied to control two different soil conditions (i.e., the stable soil water content and the dry-wet cycles) in a vegetable greenhouse growing amaranth (Amaranthus hybridus L.) and lettuce (Lactuca sativa L.). The key objective was to assess the effect of irrigation on vegetable yields and N2O emissions and further reveal their controlling factors.
Compared to FI, NPI increased the seasonal stability of soil moisture, NH4+-N, and NO3 -N by 11.4%, 26.4%, and 21.2%, respectively. NPI also increased vegetable yields by 16.6% to 20.3%, whereas the average area-scaled and yield-scaled N2O emissions under NPI were 15.1% and 29.2% lower than FI, respectively. Notably, the N2O emissions could be affected by soil moisture, temperature, NH4+-N, NO3 -N, and soil microbial biomass carbon and nitrogen, but the relative importance of these factors was different under the two irrigation systems due to different soil water conditions.
The random forest (RF) model showed that soil moisture was the most crucial factor driving N2O flux under FI, whereas soil NO3 -N and NH4+-N were the key governing factors under NPI. Overall, this study highlights the importance of increasing seasonal soil water stability for improving the sustainability of irrigation, and NPI was a promising irrigation strategy to promote vegetable yields while mitigating N2O emissions.
Li, Shengping & Song, Xiaojun & Liu, Xiaotong & Wu, Xueping & Gao, Huizhou & Lu, Jinjing & Liang, Guopeng. (2023). Negative pressure irrigation as a potential technique for increasing vegetable yields and decreasing nitrous oxide emissions.
Read the complete paper at researchgate.net