From Depletion to Restoration: Lessons From Long‐Term Monitoring of Carbon Gains and Losses in Cropping Systems

Details

• Journal Title:
  Global Change Biology
• Personal Author:
  Moore, Caitlin E. ; Blakely, Bethany ; Pederson, Taylor L. ; Gomez‐Casanovas, Nuria ; Gibson, Christy D. ; Knecht, Anya M. ; Aslan‐Sungur, Guler ; DeLucia, Evan H. ; Heaton, Emily A. ; VanLoocke, Andy ; Meyers, Tilden ; Bernacchi, Carl J.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; ARL (Air Resources Laboratory)
• Description:
  As global atmospheric CO2 rapidly approaches a key tipping point, there is an urgent need to implement strategies to reverse this pattern. A generally accepted understanding of carbon (C) in agricultural fields includes: (H1) substantial C loss occurs when natural vegetation is converted to crops, (H2) soils typically reach a steady‐state C concentration under contemporary practices, and (H3) improved management or crop selection can enhance soil C stocks over time. Significant variability exists, but studies consistently show large C losses from agricultural ecosystems, supporting H1. Although steady‐state C levels (H2) are commonly assumed, measuring C gains or losses in mature agroecosystems is challenging. Efforts to increase soil C storage (H3) have limited data due to the diversity of potential practices, compounded by substantial variability in soil C measurements. Here, long‐term (7–17 year) ecosystem C flux data from diverse cropping systems revealed that conventionally tilled annual row crops (maize and soybean) act as significant long‐term atmospheric C sources, challenging H2. Furthermore, conservation tillage practices reduced C losses compared with conventional tillage but showed minimal evidence for long‐term ecosystem C storage, even after 20+ years. This indicates that no‐till practices reduce C losses but imply that no soil C is added, challenging H3. By contrast, perennial Miscanthus × giganteus, Panicum virgatum, and restored tallgrass prairie systems store C at the ecosystem scale more effectively than minimally tilled annual row crops. Analysis over multiple years demonstrates significant ecosystem C storage with perennial crops, varying by species, starting in the first year of transition. These findings, although focused on one region, suggest that the assumptions of steady‐state C levels and increased storage from conservation practices do not universally apply and that significant changes to agroecosystems are required to increase C storage.
• Source:
  Global Change Biology, 31(6)
• DOI:
  https://doi.org/10.1111/gcb.70291
• ISSN:
  1354-1013 ; 1365-2486
• Format:
  pdf
• Publisher:
  Wiley
• Document Type:
  Journal Article
• License:
  https://creativecommons.org/licenses/by/4.0/
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:e86d7f104747202a57c1c28a5dd0a2ab4fac781c7eb3b0eaa95e21024333c532d2eed531c4ac4bb6ff2a71bb51aeacc5549cdfd009623ea557fedc1b71c3189b
• Download URL:
  https://repository.library.noaa.gov/view/noaa/71420/noaa_71420_DS1.pdf
• File Type:
  [PDF - 828.46 KB ]