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.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://jeq.scijournals.org/cgi/content/abstract/38/3/1205.
The Journal of Environmental Quality, http://jeq.scijournals.org is a peer-reviewed, international journal of environmental quality in natural and agricultural ecosystems published six times a year by the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Soil Science Society of America (SSSA). The Journal of Environmental Quality covers various aspects of anthropogenic impacts on the environment, including terrestrial, atmospheric, and aquatic systems.
The Soil Science Society of America (SSSA) is a progressive, international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, and founded in 1936, SSSA is the professional home for 6,000+ members dedicated to advancing the field of soil science. It provides information about soils in relation to crop production, environmental quality, ecosystem sustainability, bioremediation, waste management, recycling, and wise land use.
SSSA supports its members by providing quality research-based publications, educational programs, certifications, and science policy initiatives via a Washington, DC, office. For more information, visit www.soils.org.
SSSA is the founding sponsor of an approximately 5,000-square foot exhibition, Dig It! The Secrets of Soil, which opened July 19, 2008 at the Smithsonian's National Museum of Natural History in Washington, DC.