Carbon Sequestration

Environmental Sciences and Engineering Institute (ESEI)

The mission of the Environmental Sciences and Engineering Institute (ESEI) is to promote the development of science and engineering required for sustainable utilization of natural resources and for improvement of environmental quality. Our mission is realized by enhancing communication and fostering collaboration among faculty, and by supporting and assisting in project development. Our role with CASMGS is to coordinate the global climate change and carbon sequestration research here at Purdue.

Contact: Dr. Ron Turco

Agricultural Practices' Impact on Carbon Sequestration

Optimizing soil conditions to convert and retain carbon as stable SOC is the goal of those looking to sequester carbon on agricultural lands.

Dr. Tony Vyn and his group in the Agronomy Department are conducting research on the impact of tillage systems on carbon storage. Generally, SOC is protected under the large aggregate, low oxygen conditions found in no till systems. However, other conservation tillage methods may be optimal under the soil and moisture conditions found in northern Indiana and other areas of the eastern corn belt. Field studies are being conducted on experimental plots at Purdue’s Agronomy Research Center (ARC).

Moisture content of soils has a significant impact on their ability to store carbon. Wetter, cooler soils tend to hold more carbon due to the fact that decomposition (and the rate at which CO2 is released) is slower, but drainage may also affect movement of carbon through the soil profile. Dr. Sylvie Brouder’s and Dr. Eileen Kladivko’s groups in Agronomy are looking at how drainage can affect soil carbon levels. The Water Quality Field Station at the ARC and the spacing plots at SEPAC (Southeast-Purdue Agricultural Center) enables this group to measure drainage rates under different cropping and tile systems while taking soil carbon measurements and testing tile runoff for carbon as well. Their finding will lead to greater understanding of the optimal drainage systems for carbon storage on typical soil/crops conditions in this region.

Research team: Dr. Sylvie Brouder, Dr. Eileen Kladivko, Dr. Tony Vyn, Matt Ruark, Anita Gal

Biogeochemical Controls on Soils' Carbon Sequestration

In the Earth & Atmospheric Sciences Department, Dr. Tim Filley’s group is working to develop a basic understanding of the biogeochemical processes that control soil carbon storage and loss in US agricultural soils. One of the goals of CASMGS is to develop scientifically sound projections of the potential of plants and soils to sequester carbon as a part of an agricultural operation.

Efforts are targeted to accomplish this goal by quantifying the fundamental processes and mechanisms that underlie the capacity of soil to retain carbon. The group seeks to determine which plant biopolymers are most amenable to sequestration within the soil aggregate structure using a combination of stable isotope and molecular mass spectrometry. This type of knowledge will allow us to manipulate the plant-soil system to achieve the greatest possible level of carbon accumulation while simultaneously minimizing adverse effects of GHG emissions.

Contact: Dr. Tim Filley

Tools for Carbon Sequestration Development

Dr. Bernard Engel and associates in the Agricultural & Biological Engineering Department are developing computer applications in the following areas:

  • Integration of ecosystem/agronomic and economic models for prediction, assessment, and policy analysis;
  • Development of appropriate databases to support the integrated assessment models;
  • Ensuring data compatibility across modeling platforms;
  • Applications of the integrated models at multiple spatial scales, from local to national and perhaps global);
  • Sensitivity analysis of the integrated models to biophysical and economic assumptions and conditions, including inter-comparisons of alternative modeling approaches;
  • Comprehensive assessment and policy analysis, from the standpoint of addressing full greenhouse gas accounting as well as ancillary economic and environmental effects.

Contact: Dr. Bernard Engel

Tillage Effects on Carbon Sequestration and Aggregate Stability in Soils

Tony Vyn, Anita Gal

Department of Agronomy

Issue: Carbon accumulation in soils can be greatly improved by various forms of conservation management, and numerous studies have documented gains in total soil carbon at various depths intervals resulting from conservation tillage. Although there is little doubt that long-term no-till systems results in enhanced soil organic carbon accumulation (at least in near surface layers) relative to that of tillage systems based on moldboard or chisel plowing with similar crop biomass production, new questions are being raised about carbon sequestration and crop productivity when tillage systems themselves are alternated in successive years on the same site. When the continuity of a no-till system is interrupted and conventional tillage is integrated, there is less confidence in the rates of carbon accumulation. The issue of “rotational” tillage and the resulting soil quality is important in the eastern corn belt of the United States since the crop land area in “rotational “ tillage systems which periodically includes no-till far exceeds the area in continuous no-till (Vyn, 2003).

Research:  Our current studies are attempting to both assess the impact of continuous (28-year) tillage systems, as well as “rotational” tillage on soil carbon status in common maize and soybean production systems on dark and poorly drained prairie soils. We are attempting to document the carbon status to a soil depth of 1 m in multiple tillage experiments. Beside the general chemical analyses related to soil organic matter (SOM), analysis of the impact of tillage on the molecular composition of humic substances and aggregate stability measurements are also planned.

Soil structure appears to be one of the dominant controls over the decomposition of soil organic matter. Tillage breaks soil aggregates and thereby exposes SOM, which was previously protected within the aggregate structure. Conversely organic matter stabilizes aggregates, and decreases in SOM contents after cultivation are thought to be responsible for the deterioration of soil structure (Puget et al., 1995). Particulate organic matter is the most tillage-sensitive fraction of organic matter (Hussian et al., 1999). However, the relatively stable SOM pool consists of humic substances and this fraction is able to resist microbial decomposition to the greatest extent. Humic substances, therefore, help to maintain the organic matter level of soils (Hayes et al., 1989), and are significantly correlated with aggregate stability. Microaggregates are thought to be stabilized by this more persistent organic matter form (Puget et al., 1995).

Impact:  What is unique in our current study is that we are examining the influence of two factors on the relationship of aggregate stability to organic carbon: both tillage and crop rotation (continuous corn and corn-soybean rotation).

Carbon Study at Water Quality Field Station

Sylvie Brouder, Matt Ruark
Department of Agronomy

Issue: The moisture content of soils has a significant impact on their ability to store carbon. Wetter, cooler soils tend to hold more carbon due to the fact that decomposition (and the rate at which CO2 is released) is slower, but drainage may also affect movement of carbon through the soil profile. A study is being conducted to look at how drainage can affect soil carbon levels. The WQFS allows the measurement of drainage rates under different cropping systems while taking soil carbon measurements and testing tile runoff for carbon. The findings will hopefully lead to greater understanding of the optimal drainage systems for carbon storage on typical soil/crops conditions in this region.

Impact: With the concern over ever-increasing CO2 and other GHG concentrations in the atmosphere, there is hope to help offset CO2 emissions with increasing the amount of carbon stored in the soil. Management practices that enhance our ability to increase soil carbon levels offer different results under various soil and climate conditions. This research may expand our understanding of how carbon levels are affected under typical drainage conditions of this region.

Molecular and Stable Isotope Assessment of Hydrologic Influences on Organic Carbon Export from Big Pine Creek Watershed

Brent J. Dalzell, Timothy Filley and Jon Harbor
Department of Earth and Atmospheric Sciences

Research: To gain insight into the influence of hydrology on organic carbon export from agricultural land, we have initiated a molecular and stable carbon isotope study of dissolved, colloidal and particulate organic matter collected monthly and during storm events from multiple locations in Big Pine Creek watershed, a mixed land use watershed located in West-Central Indiana. The watershed is predominantly a corn-soy rotation row crop system with increasing proportions of forested land at its confluence with the Wabash River. Water samples were separated into coarse particulate organic matter, colloidal organic matter, and dissolved organic matter with glass fiber filters and cross flow ultrafiltration. The organic matter from these samples is characterized by molecular and stable isotope techniques to determine regional and botanical source using lignin oxidation products from cupric oxide oxidation.  Preliminary results show that the relative degradation of organic carbon can be dependent on stream stage.  Additional results indicate that dissolved and particulate organic carbon from Big Pine Creek is similar in degradation state to samples collected from river systems around the United States and from the Amazon River.  This suggests that the major degradation of organic carbon exported from riverine systems occurs in the small to mid-sized watersheds.  Data collected from bulk stable carbon isotope analyses show shifts between hydrologic conditions as well as size fractions, suggesting that sources of organic carbon (e.g. corn, soybeans, algae) are contributing differently to watershed export.