We study how nutrients and carbon move into, within, and out of ecosystems. We are particularly interested in applying ecosystem science to find solutions to some of today’s most challenging problems, including climate climate, sanitation, nutrient pollution, and food production. Browse below to learn more about some of our research projects. Follow our adventures in the field and lab on instagram!
We are partnering with Sustainable Organic Integrated Livelihoods (SOIL) in Haiti to improve approaches to composting human waste. The composting of human waste and its use as an agricultural soil amendment can tackle three important challenges – providing improved sanitation for vulnerable communities, reducing the spread of intestinal-born pathogens, and returning nutrients and organic matter to agricultural soils. The extent of these benefits or tradeoffs are not well known, but have important implications for the widespread adoption of this strategy to promote healthy communities and enhance food security. Our research asks three questions:
(1) How much greenhouse gases are emitted through the process of composting, and how does that compare to other waste management strategies?
(2) Does composting reduce pathogens in the environment?
(3) To what extent can capturing and composting of poop help to close Haiti’s nitrogen cycle?
(4) Can the use of compost in agriculture increase the soils ability to store carbon and grow food?
Regenerative Grazing Systems in Tropical Climates
Novel grazing practices mimicking wild ungulate’s high intensity, short duration grazing habits (called “regenerative grazing”) have been proposed as means to reverse degradation of rangeland ecosystems, increase ranch profitability, and mitigate climate change by building soil organic matter. However, very few data are available on the impact of regenerative grazing on the climate, especially in tropical climates. The goal of this project is to determine the effects of regenerative grazing management on soil carbon storage, greenhouse gas emissions, forage production, and plant community diversity.
Sustainable Manure Management using Biochar and Compost
Human activities have profoundly altered the reactive nitrogen cycle, resulting in consequences to environmental and human health. Manure is also a valuable resource that can return nutrients back to the soil, increase crop yields, and reduce reliance on chemical fertilizers. But, manure is also a major source of nitrogen pollution to the air and water. The amount of nitrogen lost to the environment is ultimately regulated by management practices. We conducted a field studies to study manure practices that aim to maximize benefits of manure nitrogen while minimizing losses to the environment. In a two-year field study conducted at two locations in the Chesapeake Bay Watershed, we amended agricultural soils with different forms of chicken manure – biochar, compost, and raw. We also measured nitrogen dynamics at a pasture-based chicken farm. The research questions we addressed included:
(1) Can the transformation of manure into more stable forms, like compost and biochar, reduce nitrogen losses to the air and water?
(2) What is the full nitrogen life cycle impact of manure-derived biochar, including emissions from biochar production, transportation, and its use as a soil amendment?
(3) What is the nitrogen budget of a pasture-base chicken farm? And, what are the unintended losses of nitrogen to the environment?
Compost Amendments to Grassland
Grasslands managed for grazing have considerable potential for mitigating climate change by increasing carbon storage in soil. Amending rangeland soils with organic matter, such as compost or manure, has been proposed as a means to increase net primary production (NPP), promote ecosystem C storage, and reduce greenhouse gas emissions from waste management. Our research tested the impacts of compost amendments to California grassland soils. This work was done in collaboration with Whendee Silver (UC Berkeley) and her group and the Marin Carbon Project (MCP). See the publications page to check out the results of soil carbon and greenhouse gas dynamics, soil carbon chemistry, ecosystem modeling, plant community composition, and greenhouse lifecycle assessment.