Carbon cycling research sheds light on land management options

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October 2, 2012

IOWA COUNTY, Iowa – New research that models how carbon moves through Midwestern landscapes will help farmers manage their land for healthy soil, clean water, and carbon sequestration.  

The project, funded by NASA’s Experimental Program to Stimulate Competitive Research (EPSCoR), seeks to quantify how carbon moves through a typical Midwestern midsize watershed in Iowa with global implications in mind.  The project team includes collaborators from the University of Iowa, University of Northern Iowa, Iowa State University, U.S. Department of Agriculture and NASA. The Leopold Center contributed special grant funding.

To find out more, watch two new videos about the project on the Leopold Center for Sustainable Agriculture’s website at www.leopold.iastate.edu/news/on-the-ground

Soils, especially the fertile soils of Iowa and its neighboring states, act like big storage bins for carbon. “The U.S. Midwest due to its clay rich soil has the greatest potential to sequester carbon – as long as the appropriate management practices are followed,” said Thanos Papanicolaou of the University of Iowa’s IIHR – Hydroscience & Engineering and Department of Civil & Environmental Engineering, the principal investigator for the project. “We have a great opportunity here in the state and beyond to contribute not just to food production but also to carbon storage as well as other environmental services.”

Scientists haven’t yet fully quantified how agricultural management practices, like those we practice in Iowa, influence carbon movement.  Questions remain about crop and soil respiration of carbon dioxide into the air. There is even less information on how tillage-induced soil erosion and deposition contribute to carbon losses or gains to the atmosphere or local waterways. Existing models have unexplained losses that influence their predictions.  

Papanicolaou’s team hopes to fill in these data and knowledge gaps. Previous studies have estimated that conservation practices on farmlands can keep nearly 33 megatons of carbon in the soil every year, thereby protecting cropland fertility and reducing the amount of carbon dioxide delivered to the atmosphere. But these studies have treated the landscape as a static ecosystem, rather than a dynamic one, and often fail to properly account for interplays between human activities and nature.

“We need to test these interactions, and there’s no better place than here in Iowa,” Papanicolaou said.

Papanicolaou’s team uses experimental plots in the Clear Creek watershed to explore the relationship between carbon and land management practices. The plots, five by fifteen feet, mimic conventional corn-soybean agriculture, Conservation Reserve Program grass, and various management practices, such as no-till and tilling at different times of the year. Researchers and students monitor each plot, measuring parameters like crop height, crop yield, leaf litter, weather-related data and soil characteristics, as well as soil organic matter and carbon dioxide.   

The Clear Creek data are utilized in two commonly used numerical models, WEPP and CENTURY. WEPP, which stands for the Water Erosion Prediction Project, models soil erosion rates under different scenarios, taking into account topography, soil characteristics, land management practices and climate. The researchers can look at single storm events or model the next 50 or 100 years.

These results go into the CENTURY model, which predicts the redistribution of carbon in the watershed. By coupling these models instead of running them independently, the researchers expect to make improved predictions of soil organic matter transport and carbon movement as it relates to land management.  One limitation could be that these models need to be coupled with advanced geospatial tools to scale up soil organic matter transport and carbon movement for larger watersheds.

To validate the results, researchers compare the data from the coupled models with on-the-ground measurements collected from different locations in the Clear Creek watershed.  

Together the models show the patterns of carbon loss due to soil movement in a typical corn-soybean system at the landscape scale and over long periods of time. The research will lead to suggested scenarios for mitigating carbon loss. Other researchers have applied similar modeling work to forests and grasslands, but little attention has been paid to agricultural fields. The researchers hope these models will inform sound policy decisions about land management.  

“We need to maintain carbon in the soils if we really are striving toward a sustainable environment,” Papanicolaou said.   
Other investigators on this project include Ph.D. students Ken Wacha and Ben Abban, Dimitrios Dermisis, former Iowa student and faculty at McNeese State University, and Christopher Wilson, assistant research scientist at IIHR-Hydroscience and Engineering.

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The Leopold Center was established by the 1987 Iowa Groundwater Protection Act as a research and education center at Iowa State University to develop sustainable agricultural practices that are both profitable and conserve natural resources. Iowa State does not discriminate on the basis of race, color, age, religion, national origin, sexual orientation, sex, marital status, disability, or status as a U.S. Vietnam Era Veteran. Any persons having inquiries concerning this may contact the Director of Affirmative Action, 3210 Beardshear Hall, (515) 294-7612.

This page was found at http://www.leopold.iastate.edu/news/10-02-2012/carbon-cycling-research on 01/21/2013