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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #341931
Title: Can conservation tillage reduce N20 emissions on cropland transitioning to organic vegetable production?

Author
item CHEN, GUIHUA - University Of Maryland
item KOLB, LAUREN - Boulder County Parks And Open Space
item Cavigelli, Michel
item WEIL, RAY - University Of Maryland
item HOOKS, CERRUTI - University Of Maryland

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2017
Publication Date: 10/28/2017
Citation: Chen, G., Kolb, L., Cavigelli, M.A., Weil, R.R., Hooks, C.R. 2017. Can conservation tillage reduce N20 emissions on cropland transitioning to organic vegetable production? Science of the Total Environment. 618:927-940.

Interpretive Summary: Conservation soil management practices such as no-till (NT) and strip-till (ST) are effective ways to sequester carbon and increase soil organic matter in agricultural lands. However, the impact of these practices on greenhouse gases (GHG) such as nitrous oxide (N2O) varies depending on soil structure, climate, and duration of the practice. In a three-year study conducted in a field transitioning to organic vegetable production using winter cover crops in the Mid-Atlantic coastal plain of the USA, researchers found that using NT and ST practices reduced N2O emissions compared to the standard practice of using tillage and black plastic mulch. Crop yield-scaled N2O emissions were consistently greatest in using tillage and black plastic mulch and lower in NT in all three years. These results suggest that under coarse-textured soils in the coastal plain, conservation tillage with winter cover crops may be able to achieve net GHG emission reduction in upland soils. These results will be of interest to government agencies such as USDA-NRCS, other scientists, and policy makers.

Technical Abstract: Conservation soil management practices such as no-till (NT) and strip-till (ST) are effective ways to sequester carbon and increase soil organic matter in agricultural lands. However, the impact of these practices on other greenhouse gases (GHG) such as nitrous oxide (N2O) varies depending on soil structure, climate, and duration of the practice. As such, a three-year study was conducted in a field transitioning to organic vegetable production in the Mid-Atlantic coastal plain of the USA to investigate impacts of two conservation tillage (ST and NT) and two conventional tillage (with black plastic mulch, CT-BP and without surface mulch – bare ground, CT-BG) on soil N2O emissions. Each year, a winter cover crop mixture (forage radish: Raphanus sativus var. longipinnatus, cv. ‘Daikon’, crimson clover: Trifolium incarnatum L., and cereal rye: Secale cereale L., cv. ‘Wheeler’) was grown and flail-mowed in spring. About 80% of annual N2O-N emissions occurred in the vegetable growing season (May – August) for all treatments. Annual N2O-N emissions were greater in CT-BP than in ST and NT and greater in CT-BG than in NT, but not different between CT-BG and CT-BP, between ST and NT, and between CT-BG and ST. Conventional tillage promoted nitrogen mineralization while black plastic mulch further increased soil temperature, which all contributed to greater N2O-N fluxes. Though water filled pore space in NT was higher and correlated well with N2O-N fluxes, annual N2O-N emissions in NT were lowest among four treatments, suggesting a lack of substrates for nitrification and denitrification processes. Crop yield was lower in NT the first year and lower in CT-BP the third year, while yield-scaled N2O-N emissions were consistently greatest in CT-BP and lower in NT in all three years. These results suggest that under coarse-textured soils in the coastal plain, conservation tillage with winter cover crops may be able to achieve net GHG emission reduction in upland soils.