Odors from cattle feedlots may one day be abated by some essential oils—chemicals like those produced by some aromatic plants. In laboratory experiments, ARS scientists essentially blocked the formation of foul-smelling volatile fatty acids when they applied as little as 1 gram of the essential oils carvacrol or thymol to half-liter slurries of cattle feces and urine. Carvacrol and thymol are constituents of oregano oil; they can also be found in thyme and many other common herbal plants. Commercially, the compounds are synthetically produced, and they are often minor ingredients in foods and personal care products. The research also showed these essential oils can reduce populations of fecal bacteria in manure slurries. Now, the scientists are taking their research to the real world—the feedlot—where they will test the essential oils against odor production and the potentially deadly fecal bacterium Escherichia coli O157:H7 and other pathogens. When pathogen-laden manure gets on the hides of cattle headed for slaughter, the risk of meat contamination during slaughtering increases.

Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE
Vincent H. Varel, (402) 762-4207, varel@email.marc.usda.gov

A 3-year survey of eastern North Carolina farm wells resulted in good news for residents concerned about drinking water quality. ARS scientists collected water samples monthly from 92 shallow groundwater wells from March 1993 to March 1995 and quarterly for the remainder of 1995 and early 1996. The wells were located on the 5,041-acre Herrings Marsh Run watershed in Duplin County, NC. Most of the watershed is farmed with row and truck crops. The region is regarded as having a high potential for groundwater contamination because of high rainfall, shallow water tables, sandy soils with low organic matter content, and high pesticide usage. The 2,598 water samples were initially screened for 11 pesticides—8 triazines, 2 chloroactamides, and 1 methylester—using immunoassay techniques. The scientists further analyzed the 266 positive detections using gas chromatographic and mass spectrometric procedures. During the study period, pesticides were consistently detected in only 4 of the 92 farm wells. And those pesticide residue concentrations were well below the health advisory or maximum contaminant levels. The survey revealed that commonly used pesticides had a minimal impact on the quality of drinking water in the area. The low amounts of pesticide residue may be due to several factors. The quantity of certain pesticides applied may have decreased because of a shift from growing corn/soybeans to cotton and because best management practices were used to apply the pesticides.

Coastal Plains Soil, Water, and Plant Research Center, Florence, SC
Jeffrey M. Novak, (843) 669-5203, ext. 110, novak@florence.ars.usda.gov

Fungi known as basidio-mycetes—the same group that includes edible mushrooms—may play a key role in maintaining and improving soil quality. In many basidiomycetes, the underground parts of the fungi—known as filaments and hyphae—produce sugary substances that with the filaments bind soil particles. This binding together, or aggregation, reduces soil compaction and allows roots, oxygen, and water to move through the soil. Mushrooms are typically associated with cool, damp, forested areas where they help to decompose fallen trees. But an ARS microbiologist found that basidiomycetes are widespread and important components of many types of soils. In open environments, the underground filaments may be plentiful without producing aboveground mushrooms, so their role is not well understood. Basidiomycetes are the second largest group of fungi known to science. The fungi survive with or without living plants and thrive on straw or crop residue left over after harvest. The scientists found greater numbers of the fungi—and better soil—in land that had been cropped without tilling. So in addition to reducing erosion, no-till practices could help improve soil quality by fostering basidiomycete populations that help to better hold soil particles together. The presence and number of these fungi may also serve as a good indicator of soil quality.

Northern Plains Agricultural Research Laboratory, Sidney, MT
TheCan Caesar, (406) 433-9411, caesart@sidney.ars.usda.gov