Location: Agricultural Systems ResearchTitle: Regulation of soil CO2 and N2O emissions by cover crops: a meta-analysis
|MUHAMMAD, IHSAN - Northwest University|
|ZHAO, FAZHU - Northwest University|
|KHAN, AHMAD - Agricultural University Peshawar|
|FU, XIN - Northwest University|
|WANG, JUN - Northwest University|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2019
Publication Date: 5/17/2019
Citation: Muhammad, I., Sainju, U.M., Zhao, F., Khan, A., Fu, X., Wang, J. 2019. Regulation of soil CO2 and N2O emissions by cover crops: a meta-analysis. Soil & Tillage Research. 192:103-112. https://doi.org/10.1016/j.still.2019.04.020.
Interpretive Summary: Impact of cover crops on greenhouse gas emissions. Cover crops can provide multiple agronomic and environmental benefits, but little information is available on their impact on carbon dioxide and nitrous oxide emissions. A meta-analysis conducted by scientists and students from ARS, Sidney, MT and Northwest University, Xian, China, showed that both legume and nonlegume cover crops produced greater carbon dioxide emissions, but legumes produced more nitrous oxide emissions than no cover crop. Cover crop residue incorporated into the soil increased both carbon dioxide and nitrous oxide emissions compared with the residue placed at surface or removed from the soil. Producers can reduce greenhouse gas emissions by using a mixture of legume and nonlegume cover crops with residue placed at the surface instead of incorporating into the soil.
Technical Abstract: Cover crops provide multiple agronomic and environmental benefits, such as enhanced soil C sequestration, aggregation, and water infiltration and reduced erosion, and nutrient leaching, compared with no cover crop. However, little is known regarding the effect of cover crop species, biomass quality and quantity and method of residue placement on greenhouse gas (GHG) emissions. Using meta-analysis, this study examined the effect of cover crop species, quality and quantity of biomass, and residue management on response ratios (RRs) of cover crops to no cover crop on CO2 and N2O emissions following cash crops. All cover crop specie increased CO2 emissions, but reduced N2O emissions compared with no cover crop, except with legumes which increased N2O emissions. The CO2 emissions increased, but N2O emissions decreased with increased cover crop biomass yield. Both CO2 and N2O emissions decreased with increased cover crop biomass C/N ratio, with greater rate of decline for legumes than nonlegumes. Cover crop residue incorporated into the soil increased CO2 and N2O emissions compared with the residue placed at surface or removed from the soil. Cover crops emitted lower CO2 and N2O emissions than no cover crops in silt loam and sandy loam soils, respectively, compared to other soil textures. Although CO2 and N2O emissions varied with cover crop species, using legume and nonlegume cover crop mixture to enhance residue C/N ratio compared to legumes and placing the residue at the surface instead of incorporating into the soil can reduce GHG emissions.Because of enhanced soil C and N storage and other known benefits, improvement in soil health and environmental quality due to cover crop may outweigh CO2 emissions compared to no cover crop.