A first-of-its-kind study of the transport and fate of two pesticides in vegetated agricultural drainage ditches suggests that ditches are valuable tools for reducing chemical runoff. Most agricultural fields are surrounded by drainage ditches that carry runoff water from fields following storms or controlled releases, as from rice fields. ARS scientists simulated a storm runoff event on the Beasley watershed—one of three Mississippi lakes in the Mississippi Delta Management Systems Evaluation Area (MSEA). The MSEA project is a national effort by the U.S. Department of Agriculture to protect farmland watersheds. It is designed to develop and test farming methods that will work with nature, instead of damaging water quality. The scientists calculated the percentage of runoff that a ditch may be exposed to during a small storm. Their goal: to pinpoint the ditch’s role in keeping irrigation water and pesticides from entering water bodies. They found that ditches trapped 60 to 90 percent of the atrazine and a commonly used insecticide, Karate, associated with the runoff. Farmers want methods to decrease the amount of potentially harmful pesticides, nutrients, and sediments leaving their fields. Ditches, through their soil and vegetation, can sequester these runoff materials, thereby decreasing potential harm to downstream lakes, rivers, and streams.

National Sedimentation Laboratory, Oxford, MS
Matthew T. Moore, (662) 232-2955, moore@sedlab.olemiss.edu

Switching dairy cows from alfalfa to red clover silage will reduce manure nitrogen levels, a boon for the environment. That’s because red clover has an enzyme—polyphenol oxidase—that reduces protein breakdown in the silo. With alfalfa, usually more than half of the protein is broken down in the silo; this results in reduced protein efficiency in the cow, according to ARS dairy scientists. In recent trials, cows fed red clover silage produced the same amount of milk as cows fed alfalfa silage, and they did so on less feed. Protein efficiency was 17 percent better on red clover than alfalfa. If this improvement applied to only the first half of lactation, when cows are fed the most protein, nitrogen excretion would be reduced by about 1.5 tons per year on a 100-cow dairy farm. Red clover grows better than alfalfa in the acidic soils common in the Midwest. Other pluses: Red clover seed is cheaper for producers than alfalfa seed, and red clover will be easier to grow—thanks to improved resistance and persistence of new varieties developed by an ARS plant breeder. ARS will release these newer varieties in the fall of 2000. Seed will be available to farmers in about 2 years.

U.S. Dairy Forage Research Center, Madison, WI
Glen A. Broderick, (608) 264-5356, glenb@dfrc.wisc.edu

Can a change in farming practices help reduce car accidents? Each year, several serious multicar accidents are caused by high winds’ blowing topsoil across highways. Standing crop residue can be 10 times more effective than flat residue in reducing wind erosion in erosion-prone areas of the West, Midwest, and Northern and Southern Plains. Erosion causes the loss of more than 2 billion tons of soil from U.S. cropland each year. Wind erosion accounts for 45 percent of this loss. To guard against erosion, ARS scientists designed a lightweight, portable scanner that can be used by farmers, crop consultants, and USDA Natural Resources Conservation Service employees to measure standing crop residue. Old ways of measuring standing crop residue were tedious and labor intensive. The standing residue scanner was modeled after a laser surface scanner developed by ARS soil scientists at the National Soil Erosion Research Laboratory in W. Lafayette, IN. Today, the original surface scanner is used around the world by soil scientists in Australia, Austria, China, and Germany. Recent improvements in the design have resulted in a new surface scanner that is 100 times faster than the original.

Wind Erosion Research Unit, Manhattan, KS
Larry Wagner, (785) 532-6807, wagner@weru.ksu.edu

Soaking willow cuttings in water for 10 days before planting doubled their survival rate along stream channel banks. Channel erosion is a serious problem in many areas. For years, researchers have tried to stabilize streambanks with planted vegetation. This can be cheaper than artificial structures and offers much environmental benefit. But success rates have varied widely, and few scientific studies have been done to find out why. ARS researchers working with scientists at the University of Memphis have focused on using large-diameter cuttings of native black willow. To find ways to enhance willow survival, the scientists ran a series of field and greenhouse studies which showed that cuttings are very sensitive to the amount of moisture and sandiness of the underground environment. To improve survival rates, the scientists tried soaking some cuttings in water for 3 or 10 days before planting them; some weren’t soaked at all. Those soaked for 10 days far outperformed the others, showing better growth, biomass production, number of roots, and other benefits. This finding will be of great interest to all who are working to restore the nation’s degraded streams.

National Sedimentation Laboratory, Oxford, MS
F. Douglas Shields, Jr., (662) 232-2919, shields@sedlab.olemiss.edu

Farmers may have an answer to their questions about varying crop yields within a field. Using satellite global positioning systems and combine monitors, scientists and farmers have documented this variability of yields. They want to determine what combination of soil, weather, and management factors is causing it. This information should increase yields and reduce costly chemical inputs, which in turn would lower the risk of contaminating water resources. ARS researchers working with Iowa State University-Ames scientists have found that higher yields may be influenced partly by management practices and topography at the lowest field elevations, while lower yields seem linked to soil types and topography. They measured the yield variability of corn and soybeans within a 50-acre farm field and related it to soil properties—in particular, the Soil Tilth Index. Developed at the National Soil Tilth Laboratory, this index of soil health ranks the soil’s suitability as a seedbed, which is an accurate predictor of crop yield variation. The index accurately predicted corn and soybean yield, but only for part of the field. Factors other than tilth determined crop yield for the remainder.

National Soil Tilth Laboratory, Ames, IA
Thomas S. Colvin, (515) 294-5724, colvin@nstl.gov

ARS scientists are pioneering new efforts in “green technology,” using plants to clean up soils contaminated with heavy toxic metals. Contaminated soils and waters pose major environmental, agricultural, and human health problems worldwide. These problems may be partially solved by a new technology called phytoremediation. It uses green plants to remove pollutants from the environment or render them harmless. Current engineering-based technologies used to clean up these soils—like removing contaminated topsoil for storage in landfills—are very costly and dramatically disturb the landscape. But green technology uses certain plant species, known as metal hyperaccumulators, to “vacuum up” heavy metals from the soil through their roots and store them in aboveground plant tissue. Once extracted from soil and concentrated in the easily harvested plant stems and leaves, these elements can be collected, reduced in volume, and stored for later use. Scientists are studying plants like Thlaspi caerulescens, which thrives on soils contaminated with high levels of zinc and cadmium, and Amaranthus retroflexus, which removes up to 40 times more radiocesium from soil than other plant species tested.

Plant, Soil, and Nutrition Laboratory, Ithaca, NY
Leon V. Kochian, (607) 255-2454, (607) 255-2459, lvk1@cornell.edu