Paper: “The climate change mitigation potential of annual grasslands under future climates,” Ecological Applications. 2022;e2705. https://doi.org/10.1002/eap.2705.
Research Team: Mayer, Allegra, and Whendee L. Silver
Findings: A one-time amendment of com- post to rangeland acted as a slow-release organic fertilizer and increased NPP by up to 390–814 kg C ha-1 year-1 across sites. The amendment effect on NPP was not sensitive to Earth system model or emissions scenario and endured through the end of the century. Net SOC sequestration amounted to 1.96 0.02 Mg C ha-1 relative to unamended soils at the maximum amend- ment effect. Averaged across sites and scenarios, SOC sequestration peaked 22 +/- 1 years after amendment and declined but remained positive throughout the century. Though compost stimulated nitrous oxide (N2O) emissions, the cumulative net emissions (in CO2 equivalents) due to compost were far less than the amount of SOC sequestered. Compost amendments resulted in a net climate benefit of 69.6 +/- 0.5 Tg CO2e 20 +/- 1 years after amendment if applied to similar ecosystems across the state, amounting to 39% of California’s rangeland. These results suggest that the biogeochemical benefits of a single amendment of com- post to rangelands in California are insensitive to climate change and could contribute to decadal-scale climate change mitigation goals alongside emissions reductions.
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