A global meta-analysis of cover crop on soil carbon storage within a corn production system

Authors: JOSHI, DEEPAK - South Dakota State University; SIEVERDING, HEIDI - South Dakota School Of Mines And Technology; XU, HUI - Argonne National Laboratory; KWON, HOYOUNG - Argonne National Laboratory; WANG, MICHAEL - Argonne National Laboratory; CLAY, SHARON - South Dakota State University; Johnson, Jane; THAPA, RESHAM - Tennessee State University; WESTHOFF, SHANIA - South Dakota State University; CLAY, DAVID - South Dakota State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2023
Publication Date: 5/10/2023
Citation: Joshi, D.R., Sieverding, H.L., Xu, H., Kwon, H., Wang, M., Clay, S.A., Johnson, J.M., Thapa, R., Westhoff, S., Clay, D.E. 2023. A global meta-analysis of cover crop on soil carbon storage within a corn production system. Agronomy Journal. https://doi.org/10.1002/agj2.21340.
DOI: https://doi.org/10.1002/agj2.21340

Interpretive Summary: Meta-analysis is a tool for identifying overall trends by comparing results of many independent studies. The current project used meta-analysis to understand the effect of cover crops on soil organic carbon (SOC) within corn-based cropping systems. Cover crops are plant species grown following a cash crop to provide soil coverage. Benefits attributed to cover crops include reduced erosion and increased SOC. Increasing SOC can mean removing a corresponding amount of carbon dioxide from the atmosphere. Also, increasing SOC typically results in healthier soil. The objective of this work was assessing the ability to cover crops to increase SOC when used in corn systems. Our findings showed that SOC storage in no-tillage was 8.5% and that carbon storage in tilled systems were 6.61%. In a corn (Zea mays) following corn rotation carbon storage was 8.58%; whereas, in a corn following soybean (Glycine max) rotation carbon storage was 5.11%. These data suggest that the current cover crop/corn production systems are sequestering 5.5 million tons per year in the United States and have potential to sequester 175 million tons per year globally. Along with increasing the SOC, adopting cover crop increased corn yield 23%. These findings can be used to improve C footprint calculations and develop science-based policy recommendations.

Technical Abstract: In agriculture, the carbon (C) cycle can be separated into three pools: carbon dioxide (CO2) in the atmosphere, organic C in plant and animal tissues, and organic C in the soil. Within this system, photosynthesis converts atmospheric CO2 to organic C in plants, which is eventually oxidized to CO2 through respiration. If C fixation is greater than respiration, then soil organic C levels can increase. The hypothesis of this paper is that by increasing CO2 fixation, cover crops increase soil organic carbon (SOC). The objective was to conduct a meta-analysis on the effect of cover crop adopted within a rotation that includes corn (Zea mays) system on SOC. Of the 3856 identified published cover crop studies, only 62 provided an adequate amount of information to be included in the study. Overall, cover crop in corn rotations field increased SOC by 7.8%. The SOC increase was attributed to the cover crop enhanced CO2 fixation by the cover crop being greater than the amount of SOC lost through respiration. Our findings showed that SOC storage in no-tillage was 8.5% and that C storage in tilled system was 6.61%. In a corn (Zea mays) following corn rotation C storage was 8.58%; whereas, in a corn following soybean (Glycine max) rotation C storage was 5.11%. These data suggest that the current cover crops/corn production systems are sequestering 4.98 million Mg of SOC-C year-1 in the United States and has potential to sequester 159.2 million Mg SOC year-1 globally. Along with increasing the SOC, adopting cover crop increased corn yield 23%. These findings can be used to improve carbon footprint calculations and develop science-based policy recommendations.