Greenhouse gas emissions and management practices that impact them in US rice systems

Authors: LUNQUIST, BRUCE - University Of California, Davis; MARCOS, MATHIAS - University Of California, Davis; Adviento-Borbe, Arlene; ANDERS, MERLE - American Biocarbon Ct, Llc; HARREL, DUSTIN - Louisana State University; LINSCOMBE, STEVE - Louisana State University; Reba, Michele; RUNKLE, BENJAMIN - University Of Arkansas; TARPLEY, LEE - Texas A&M Agrilife; THOMPSON, ALLISON - Field To Market: The Alliance For Sustainable Agriculture

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2018
Publication Date: 5/3/2018
Citation: Lunquist, B.A., Marcos, M., Adviento-Borbe, A.A., Anders, M., Harrel, D., Linscombe, S., Reba, M.L., Runkle, B.R., Tarpley, L., Thompson, A. 2018. Greenhouse gas emissions and management practices that impact them in US rice systems. Journal of Environmental Quality. 47(3):395–409. https://doi.org/10.2134/jeq2017.11.0445.
DOI: https://doi.org/10.2134/jeq2017.11.0445

Interpretive Summary: Rice cultivation is a significant source of methane emissions, accounting for 9-11% of greenhouse gas (GHG) emissions from agriculture globally. Current guidelines to estimate total GHG from rice systems and to identify factors influencing magnitude of emissions have been focused on Asia where about 90% of world' rice is produced. However, US rice production practices are different from Asian rice management thus existing emission factors may not be applicable to US GHG inventories. This paper summarized data from peer-reviewed publications of US rice emissions. Management practices that affect gas emissions were highlighted and used to create emission factors relevant to US rice production. The practice of alternate wetting & drying irrigation, straw burning which reduced crop residue, application of sulfur, use of hybrid CLXL 745 and dry seeding reduced CH4 emissions by 3 to 83%. More studies are needed to accurately estimate total CH4 emissions from rice ratooning. Nitrous oxide emissions remained small relative to CH4 emissions across US rice regions. This information will benefit researchers, national and international scientific working groups on GHG inventories and importantly rice growers on trading of carbon emissions to Carbon Credit Marketplace.

Technical Abstract: Previous reviews have quantified factors affecting greenhouse gas (GHG) emissions from Asian rice (Oryza sativa L.) systems, but not from rice systems typical for the United States, which often vary considerably particularly in practices (i.e., water and carbon management) that affect emissions. Using meta-analytic and regression approaches, existing data from the United States were examined to quantify GHG emissions and major practices affecting emissions. Due to different production practices, major rice production regions were defined as the mid-South (Arkansas, Texas, Louisiana, Mississippi, and Missouri) and California, with emissions being evaluated separately. Average growing season CH4 emissions for the mid-South and California were 194 (95% confidence interval [CI] = 129–260) and 218 kg CH4 ha-1 season-1 (95% CI = 153–284), respectively. Growing season N2O emissions were similar between regions (0.14 kg N2O ha-1 season-1). Ratoon cropping (allowing an additional harvestable crop to grow from stubble after the initial harvest), common along the Gulf Coast of the mid-South, had average CH4 emissions of 540 kg CH4 ha-1 season-1 (95% CI = 465–614). Water and residue management practices such as alternate wetting and drying, and stand establishment method (water vs. dry seeding), and the amount of residue from the previous crop had the largest effect on growing season CH4 emissions. However, soil texture, sulfate additions, and cultivar selection also affected growing season CH4 emissions. This analysis can be used for the development of tools to estimate and mitigate GHG emissions from US rice systems and other similarly mechanized systems in temperate regions.