Unraveling crop residue harvest effects on soil organic carbon

Authors: Karlen, Douglas; Schmer, Marty; KAFFKA, STEPHEN - University Of California, Davis; CLAY, DAVID - South Dakota State University; WANG, MICHAEL - Argonne National Laboratory; HORWATH, WILLIAM - University Of California, Davis; KENDALL, ALISSA - University Of California, Davis; KELLER, ALAN - Poet; PIEPER, B.JOHN - Dupont Industrial Biosciences; UNNASCH, STEFAN - Life Cycle Associates; DARLINGTON, TOM - Air Improvement Resource, Inc; VOCASEK, FRED - Servi-Tech Laboratories; CHUTE, ALAN - Iowa Agricultural Bio Fibers

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2018
Publication Date: 11/15/2018
Publication URL: https://handle.nal.usda.gov/10113/6550005
Citation: Karlen, D.L., Schmer, M.R., Kaffka, S.R., Clay, D.E., Wang, M.Q., Horwath, W.R., Kendall, A.M., Keller, A., Pieper, B., Unnasch, S., Darlington, T., Vocasek, F., Chute, A.G. 2018. Unraveling crop residue harvest effects on soil organic carbon. Agronomy Journal. 111:93-98. https://doi.org/10.2134/agronj2018.03.0207.
DOI: https://doi.org/10.2134/agronj2018.03.0207

Interpretive Summary: The American Society of Agronomy (ASA) was asked by a farmer/ethanol investor for help with regard to the sustainability of biofuel production from corn stover. This report summarizes development and outcomes of a national conference and serves as an introduction for a special issue of the journal reporting on the outcomes of the workshop. The information will be useful to farmers, ethanol investors, biofuel associations, conservationists, regulators, action agency personnel and the scientific community.

Technical Abstract: Crop residues have many different roles including protecting soil resources, sustaining soil organic carbon (SOC), cycling nutrients, supporting microbial communities, and providing feedstock for bioenergy or bio-product production. Our objectives are to: (1) summarize what led the ASA-CSSA-SSSA to organize a “Crop Residues for Advanced Biofuels: Effects on Soil Carbon” workshop, (2) review the Workshop structure, and (3) present consensus points, unanswered questions, and Workshop outcomes. Initiated by a farmer/ethanol investor’s letter to the ASA President, the A808 Working Group (WG) was established and after discussing the request, concluded a Tri-Society sponsored workshop involving farmers, ethanol production and marketing groups, agronomists, crop scientists, soil scientists, engineers, NGOs, life cycle analysis (LCA) experts, and regulatory personnel was needed to address the complex question and ensure all viewpoints were fully represented. The WG also recommended that a public and transparent process and record should be used during the workshop and subsequently used to create both technical and educational materials. The WG was expanded to Task Force 1607 who organized the workshop in Sacramento, CA so that California Air Resources Board (CARB) personnel could participate more easily. Four consensus areas [crop residue management (CRM); severity of soil erosion; tillage, CRM and erosion linkages; and importance of simulation (LCA) models] and four unresolved themes [forgone carbon sequestration, CRM effects on SOC stocks, changing climate effects, and the importance of “ecosystem services” rather than single endpoints] were identified. Next steps, including (1) a stakeholder funded SOC database, (2) LCA and SOC model improvements, and (3) development of this special issue which addresses several of the concerns, were direct outcomes of a very successful ASA-CSSA-SSSA workshop.