Natural Resource Ecology Laboratory

Research Program

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Preserving Soil Organic Matter in a Changing World

Soil organic matter is the very thin skin on the world’s terrestrial surface, and is the most chemically complex and least-understood component of terrestrial ecosystems. This organic matter serves many functions vital to humanity, such as regulating water flow and supplying nutrients to plants. Hence, the preservation of soil organic matter is vital for the sustainability of food, fiber, and energy production. Soil organic matter is formed through the decomposition of plant material by many organisms living in the soil, and its persistence depends on a variety of factors, most notably, its sensitivity to soil management and climate. Understanding the basic processes that control soil organic matter formation and persistence under land use and climate changes is imperative to propose soil management solutions that assure the preservation of soil functions and a sustainable future for an ever-growing global population.

We use stable isotope labeling, coupled to field manipulations, SOM physical fractionation, compound specific analyses and other state-of-the-art methods to study the formation and persistence of soil organic matter in a variety of terrestrial ecosystems.

Currently this work is supported by the NSF-DEB and the DOE-TES.

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BIOCHAR: A Sustainable Solution to Improve Food Production and Soil Reclamation and Mitigate Climate Change

Biochar is the carbon-rich solid co-product of thermochemical biofuel production, which has been advocated as a good soil amendment capable of sequestering carbon while improving crop yields and ecosystem sustainability. The recovery of biochar from biofuel production systems and its use in critical managed soils has the potential to increase economic returns, while improving environmental quality and enhancing the overall sustainability of the system. Biochar is characterized by several specific characteristics that result in many well-documented benefits to agricultural soils, including: 1) increased aeration, water retention, and structural stability of soils; 2) increased soil carbon sequestration; 3) reduced greenhouse gas (e.g., N2O) emissions from soils; 4) increased pH and nutrient retention capacity (e.g., decreased leaching losses of available nitrate and ammonium); 5) reduced mobility of contaminants; and, thus 6) promotion of soil fertility and plant growth. Our biochar research coupling isotopic techniques to laboratory and field studies, investigates the basic mechanisms underlying the beneficial effects of biochar to its application for food production in dryland and the recovery of degraded soils.

This program is supported by the USDA and the Cotrufo-Hoppess fund for soil ecology research.

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Black Carbon Dynamics

Every year, fire burns several million hectares of forests, grasslands, and savannas, across the globe, and the frequency and intensity of these fires are likely to increase in the future. During fire, some of the burned biomass is converted to black carbon, which is then released into the atmosphere or deposited on the soil as char. Although this char can be utilized by soil microbes, its decomposition occurs at a very, very slow rate. Thus, black carbon generally resides in the soil for a long time (from centuries to millennia), and acts as a long-term carbon sink, thus mitigating global warming. However, the amount of black carbon stocks in soils is not only affected by rates of production and decomposition, but also through losses attributed to wind erosion, runoff, leaching, or subsequent burning. In burned watershed, rivers become black, and the black water may be used downstream for irrigation and other uses. What is then the impact of black carbon in the environment?

We use the Benzene Polycarboxylic Acid (BPCA) markers to quantify black carbon in the environment, and isotopically labeled pyrogenic organic matter to investigate its fate and effects on soil, soil organisms, and water.

This research is funded by the NSF-DEB and International program.

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Sustainable Bioenergy:
Expanding assessments of Bioenergy sustainability to soil organic matter dynamics and carbon sequestration

Bioenergy production is an important component of mitigating climate change and curtailing the use of fossil fuels in the United States and around the world. Enhancing the sustainability of bioenergy feedstock production, through best management practices and regionally appropriate feedstock selection, is crucial to our ability to optimize land use and to meet the multiple demands placed on agricultural lands, such as food, feed, fiber, and fuel production.

We have begun examining the impacts of bioenergy feedstocks on soil carbon sequestration, and how this capacity for carbon storage may vary by region and by feedstock. Roots often are the primary organic matter inputs in agricultural systems, especially in the deep soil. Through decomposition experiments in agroecosystems with the bioenergy feedstock Sorghum bicolor, we are advancing our basic knowledge of the contribution of crop roots to changes in soil carbon pools, and how long the carbon is likely to remain in the soil at the surface and in the deep soil. Thus, we can better inform sustainability assessments of carbon sequestration potential and make better decisions about what feedstocks we should produce.

This research is funded by the USDA NIFA, through a doctoral fellowship to Sarah Fulton-Smith.

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