Study of agricultural watersheds and carbon losses

Jun 19, 2009

Dissolved organic carbon (DOC) losses from tile drains are an underquantified portion of the terrestrial carbon cycle. This is particularly important in the eastern corn belt where tile drainage dominates the agricultural landscape. Specific land management practices, such as manure application, can play a large role in the export of DOC as soluble organic carbon is applied to or injected into the soil surface. As animal agriculture intensifies in the upper Midwest, measuring DOC exported through tile drains is important when evaluating carbon budgets and carbon sequestration potential.

Scientists at Purdue University have investigated the impacts of manure application, crop rotation, and nitrogen application rate on DOC losses from tile drains. Research was conducted over a six-year span (1998-2004) at Purdue University's Water Quality Field Station, which was designed specifically to measure drainflow and solute losses from agricultural practices. Forty-eight drainage lysimeters were established at the field site in 1992.

Twelve field treatments included a restored prairie grass, continuous corn rotations and corn-soybean rotations fertilized at three nitrogen rates, and continuous corn rotations fertilized with lagooned swine effluent applied in the spring or fall of each year. The study was funded by the USDA through Consortium for Agricultural Soils Mitigation of Greenhouses program and through the CSREES-NRI Watershed Processes and Water Resources Grant; the results were published in the May issue of the Journal of Environmental Quality.

The study determined that annual losses of DOC were not affected by any crop management practice. However, when drainage-inducing rainfall occurred with one month of manure application, the monthly DOC concentration of the manured plot was greater than that of non-manured plots. Overall, drainage hydrology was determined to be the largest sole driver of DOC loss. Greater daily drainflows were associated with higher DOC concentrations compared to lower daily drainflows. This indicates that larger storms effectively "flush" DOC from the soil systems.

Dr. Matt Ruark, now an Assistant Professor at the University of Wisconsin-Madison, stated, "Understanding the concentrations and amounts of DOC contributed to surface waters from tile drains is essential for evaluating the overall aquatic ecology of a watershed. This is of particular importance in the eastern corn belt, where up to 80% of the land in agricultural watersheds are tile drained."

Further research is required to evaluate the fate of tile drainage-exported DOC once it enters the surface water system. The effect of manure management on the availability of DOC leached into subsurface soil is currently being investigated. Ongoing research at the water quality field station is being conducted to quantify nutrient and contaminant losses in tile drains as a result of manure application and crop rotation.

More information: jeq.scijournals.org/cgi/content/abstract/38/3/1205

Source: American Society of Agronomy

Explore further: Rising anger as Nicaragua canal to break ground

add to favorites email to friend print save as pdf

Related Stories

Alternative farming cleans up water

Jul 19, 2007

Although the addition of nutrients to soil helps to maximize crop production, fertilizer can leach nutrients, polluting the water supply. A recent study by researchers at the University of Minnesota shows alternative cropping ...

Managing carbon loss

Dec 03, 2008

As the United States continues to develop alternative energy methods and push towards energy independence, cellulosic-based ethanol has emerged as one of the most commercially viable technologies. Corn stover remains the ...

Improving swine waste fertilizer

Jul 08, 2008

Swine production generates large amounts of waste. While this waste contains nutrients that may serve as fertilizer when applied to agricultural fields, the ratio of nutrients in the waste is different than what a crop requires.

Mystery on the Hudson

Apr 05, 2005

Carbon exists in many forms in the air, soil, and water, and is an integral part of most living organisms. In a recent study, Stuart Findlay (Institute of Ecosystem Studies, Millbrook, New York) discovered changes in the ...

The 5 Ws of corn production

Aug 31, 2007

As of late, many uncertainties have been sprouting up in corn production. Researchers and producers have been wondering if precision agricultural technologies can improve crop yield and quality or reduce their variability. ...

Recommended for you

Rising anger as Nicaragua canal to break ground

5 hours ago

As a conscripted soldier during the Contra War of the 1980s, Esteban Ruiz used to flee from battles because he didn't want to have to kill anyone. But now, as the 47-year-old farmer prepares to fight for ...

Hopes, fears, doubts surround Cuba's oil future

Dec 20, 2014

One of the most prolific oil and gas basins on the planet sits just off Cuba's northwest coast, and the thaw in relations with the United States is giving rise to hopes that Cuba can now get in on the action.

New challenges for ocean acidification research

Dec 19, 2014

Over the past decade, ocean acidification has received growing recognition not only in the scientific area. Decision-makers, stakeholders, and the general public are becoming increasingly aware of "the other carbon dioxide ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.