What are the Lifecycle Greenhouse Gas Implications of Soil Amendments on Rangelands? 

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Research Team

Marcia S. DeLonge,* Rebecca Ryals, and Whendee L. Silver (Ecosystem Sciences Division, Department of Environmental Science, Policy, and Management,  University of California at Berkeley)

Methods 

Researchers designed a field-scale model that quantifies greenhouse gas emissions (CO2, CH4, and N2O) from the production, application, and ecosystem response of soil amendments. Using this model, researchers developed a set of case studies for grazed annual grasslands in California. Sensitivity tests were performed to explore the impacts of model variables and management options, including typical manure and fertilizer applications. Finally, researchers conducted Monte Carlo simulations to provide estimates of the potential error associated with variables where literature data were sparse or spanned wide ranges.

Results 

  • Composted manure and plant waste produced less greenhouse gas emissions than either the application of manure slurries or the application of inorganic N fertilizer across a broad range of environmental and management conditions.  
  • Secondary benefits were also achieved by only compost amendments, including increased plant productivity, soil C sequestration, and reduced need for commercial feeds.
  • Compost amendments could result in significant offsets to greenhouse gas emissions, amounting to over 28 MMg CO2e when scaled to 5% of California rangelands, while sustaining productive lands and reducing waste loads.