Extension Ag Update
January/February 2007
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Wetlands Curb Hog Hormones in Waste Water

Jan Suszkiw, ARS News, (301) 504-1630, jan.suszkiw@ars.usda.gov

Constructed wetlands may help reduce hormones in wastewater from hog farms.  Recently, hog-farm operators have begun incorporating constructed wetlands into their wastewater treatments to reduce nitrogen and phosphorus in the effluent so that it can be spread onto crop fields without causing environmental harm. But little, if any, research has investigated the system's potential to diminish hormones that hogs excrete into wastewater. There is increasing concern that hormones from livestock waste and other sources are accumulating in the environment and disrupting the endocrine-system function of fish and other aquatic life.

The study conducted at a Greensboro hog-farrowing facility, checked for reproductive hormones--estrogens and androgens (including testosterone) and their metabolites. First, wastewater from the facility went into a manure pit, then into a series of lagoons for microbial degradation. Next, the effluent was pumped into one of four wetlands, then into a storage pond. To close the circuit, some of the "gray" water was flushed back into the barns. The wetland consisted of marsh areas with cattails and pond area, which was either open or covered with floating mats of vegetation.

The researchers took water samples over three seasons in 2004, and weekly in July 2005. They analyzed them for hormones, including a naturally secreted estrogen called estradiol, using liquid-chromatography mass-spectrometry analysis and the E-screen. The latter contains human mammary cells that multiply when exposed to estrogenic compounds.  By analyzing the effluent both before and after passing through the constructed wetlands, they determined the wetlands reduced estradiol activity by 83 to 93 percent. This reduction included estrone, the most prevalent of the estradiol metabolites.

Researchers included: Nancy Shappell and Lloyd Billey with the ARS Biosciences Research Laboratory in Fargo, N.D.; Dean Forbes and G.P. Reddy of North Carolina Agricultural and Technical State University at Greensboro; and Terry Matheny, Matthew Poach and Patrick Hunt at the ARS Coastal Plain Soil, Water and Plant Research Center in Florence, S.C

Adjusting Fertilizer To Create Low-Phytate Crops

Don Comis, ARS News, (301) 504-1625, donald.comis@ars.usda.gov

Giving too much phosphorus to wheat and barley plants has been shown to raise the amount stored as phytate, rather than as more digestible forms of phosphorus. This finding is important for two reasons: Livestock that are fed high-phytate grains excrete more phosphorus in their manure, which can pollute water. Also, phosphorus is a finite resource that could be irreplaceable once it has been thoroughly mined--which could happen in the next 25 years.   Agricultural Research Service (ARS) geneticist Edward J. Souza, ARS Soft Wheat Quality Research Unit, and colleagues at the University of Idaho Research and Extension Center in Aberdeen--David Bowen, Pioneer Hi-Bred International, Inc., Johnston, Iowa, Mary J. Guttieri,  Ohio Agricultural Research and Development Center in Wooster and Karen M. Peterson--made the discovery.

The researchers found that soil phosphorus levels may affect grain phytate levels as much as plant breeding can, offering two complementary solutions to the nutritional and environmental problems caused by high phytate levels in grains. Besides being more environmentally sound, getting the application rate for phosphorus fertilizers just right might improve the nutrients delivered by grain crops such as wheat and barley.  Not only is the phosphorus in low-phytate grain crops more digestible by people, but low-phytate grains free up minerals essential to human nutrition: zinc, manganese and iron.

No-till’s Environmental Benefits Disappear Quickly If Soil Is Tilled

A. S. Grandy, G. P. Robertson, and K. D. Thelen

No-till reduces erosion and improves soil quality. Despite its benefits, only some no-till land remains in permanent no-till. Concerns regarding no-till include wet and cold soils, delayed planting and reduced nitrogen availability. In the Agronomy Journal, Vol. 98, researchers showed that even in northern climes, long-term, no-till yields could equal or exceed those in tilled systems. No-till management increased soil aggregation and surface-soil carbon concentrations, and didn’t impact average nitrous oxide emissions. However, tilling long-term, no-till systems had immediate and sustained adverse effects on soil structure, organic matter and microbial processes. Producers can use no-till, but must identify challenges and create practices to address concerns.

State of the World’s Animal Genetic Resources

United Nations

The United Nations has warned that around 20 percent of domestic animal breeds worldwide are at risk of extinction, with a breed lost each month. The organization blames globalization and a focus on high-production breeds for the loss of 190 breeds in the past 15 years, and says 1,500 more breeds are at risk of extinction. The UN notes that many traditional breeds are multi-purpose animals, while modern breeds are highly specialized. The organization cautions that the existing gene pool holds valuable resources for future food security and agricultural development, particularly in harsh environments. An international conference set for Switzerland in September is to adopt a plan to help stop the loss of genetic diversity in domestic animal breeds.