Irrigation and Greenhouse Gas Emissions: A Review of Field-Based Studies

Abstract

Irrigation practices can greatly influence greenhouse gas (GHG) emissions because of their control on soil microbial activity and substrate supply. However, the effects of different irrigation management practices, such as flood irrigations versus reduced volume methods, including drip and sprinkler irrigation, on GHG emissions are still poorly understood. Therefore, this review was performed to investigate the effects of different irrigation management strategies on the emission of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) by synthesizing existing research that either directly or indirectly examined the effects of at least two irrigation rates on GHG emissions within a single field-based study. Out of thirty-two articles selected for review, reduced irrigation was found to be effective in lowering the rate of CH4 emissions, while flood irrigation had the highest CH4 emission. The rate of CO2 emission increased mostly under low irrigation, and the effect of irrigation strategies on N2O emissions were inconsistent, though a majority of studies reported low N2O emissions in continuously flooded field treatments. The global warming potential (GWP) demonstrated that reduced or water-saving irrigation strategies have the potential to decrease the effect of GHG emissions. In general, GWP was higher for the field that was continuously flooded. The major finding from this review is that optimizing irrigation may help to reduce CH4 emissions and net GWP. However, more field research assessing the effect of varying rates of irrigation on the emission of GHGs from the agricultural field is warranted.

Biological Waste Air and Waste Gas Treatment: Overview, Challenges, Operational Efficiency, and Current Trends

“…In industrial applications, irrigation can be continuous or intermittent and the flow rate can be both adapted to hydrophilic or lipophilic characteristics of the waste gas compounds and the wetting behavior of the package [20,21]. In case of agricultural or municipal applications, which are often characterized by NH 3 emissions, continuous spraying is strictly necessary to minimize N 2 O emissions, since otherwise an average of 26% of the NH 3 -N load is released as N 2 O-N into the clean gas [22,23]. Since the flow rate is still only approximately 1-10% of that of the bioscrubber, this procedure is called semi-wet system, but it can still be used for dosage of nutrients or alkaline for neutralization, as well as pre-humidification of the waste gas [5,9].…”

Formation and Fluxes of Soil Trace Gases

“…Although the laboratory incubations they performed were made with soil from the same field plots and the same type of biochar as the field experiment, they were unable to obtain consistency between biochar effects on N 2 O and CO 2 emissions as measured in the lab relative to the field. Along these same lines, Sapkopta et al (2020) review the available literature to understand how reductions in irrigation in agricultural systems influence soil emissions of CO 2 , N 2 O, and CH 4 and their associated global warming potential, and find consistent increases in CO 2 and decreases in CH 4 emissions, but inconsistent trends in the response of soil N 2 O emissions to irrigation treatment [11]. In both manuscripts, reasons for discrepancy between laboratory and field and across field studies are discussed, some of which may be relatively easily addressed in future studies, through even more strictly regimented matching of experimental materials and designs and more expansive field experimental approaches [10,11].…”

“…Along these same lines, Sapkopta et al (2020) review the available literature to understand how reductions in irrigation in agricultural systems influence soil emissions of CO 2 , N 2 O, and CH 4 and their associated global warming potential, and find consistent increases in CO 2 and decreases in CH 4 emissions, but inconsistent trends in the response of soil N 2 O emissions to irrigation treatment [11]. In both manuscripts, reasons for discrepancy between laboratory and field and across field studies are discussed, some of which may be relatively easily addressed in future studies, through even more strictly regimented matching of experimental materials and designs and more expansive field experimental approaches [10,11]. That said, laboratory experiments will always have challenges to represent natural temperature and soil moisture fluctuations, plant and other biological inputs/effects, and differences in physical and biochemical properties of soil (i.e., spatial heterogeneity).…”

“…Similarly, Jones et al (2018) utilized laboratory incubations, allowing for isotopic labeling and controlled environmental conditions, in parallel with their elaborate field measurements, to assess gross fluxes of CH 4 and further elucidate underlying mechanisms that could explain their observed field variability in CH 4 emissions. This approach may be well suited to more conclusively pinpoint impacts on soil GHG emissions by reducing irrigation to agricultural systems [11].…”

Gasification of Cup Plant (Silphium perfoliatum L.) Biomass–Energy Recovery and Environmental Impacts

“…An important factor in the cultivation of energy crops is the relationship between agrotechnical activities and the amount of energy obtained. Carbon sequestration as a result of irrigation and fertilization is 0.12-3.46 and 0.32-0.74 Mg of C per 1 ha per year, respectively [5]. Fertilization and irrigation are among the treatments most affecting the productivity of plant biomass, as well as the amount of energy obtained.…”