Water quantity and quality issues have increasingly become the focus of attention of United States citizens, private and public organizations, and units of government striving to meet competing demands while protecting the environment and public health. Sound agricultural management practices are required to ensure success in maintaining a healthy and productive land and water base that sustains local communities, food and fiber production, and also protects and restores critical natural systems.
Research in this National Program addresses three component problem areas: (1) agricultural watershed management; (2) irrigation and drainage management; and (3) water quality protection and management. The purpose of the Water Quality and Management National Program is to provide practical tools and techniques to meet the needs of farmers, ranchers, and other entities involved in controlling, assessing, regulating, and managing water resources. Based on customer input, the agricultural watershed management component fosters research on climate and weather uncertainties, risks, and extremes; water scarcity and drought mitigation; control strategies and infrastructure; watershed characterization, processes, responses; riparian, stream, and wetland ecosystems; and watershed modeling and planning tools. The irrigation and drainage management systems component stresses high-value irrigated crop production, precision irrigated agriculture, water conservation, irrigated wastewater reuse, environmental impacts on irrigated lands, erosion on irrigated lands, salinity management, and drainage management. The water quality protection and management systems component focuses on research on potential agricultural contaminants in surface and groundwaters; water quality model evaluation, testing, and improvement; integrated field, farm, and watershed management systems; and risk and economic evaluation. Brochures describing the challenges and opportunities for watershed management research and irrigation and drainage management research are available on the ARS website found at http://www.ars.usda.gov/is/np/watershed/watershedintro.htm.
Improved communications, research coordination, and technology transfer are being stressed among scientists, customers, stakeholders, and partners as important goals in the planning and implementation process of this National Program. ARS is leading a cooperative effort with assistance from the Natural Resources Conservation Service (NRCS) and US Geological Survey (USGS) to develop a method to streamline the development time and reduce the maintenance costs of computer implemented decision support systems for evaluating conservation systems. This new framework for modeling is called the Object Modeling System and was developed by the ARS Great Plains System Research Unit in Fort Collins, Colorado. This system has been adopted by NRCS as a means of deploying web-implemented decision support systems to their more than 2,000 field locations. When completed, this new framework for modeling will greatly accelerate the development and deployment of natural resource decision support system tools by the NRCS.
A new Joint U.S.-China Center for Soil and Water Conservation and Environmental Protection, was dedicated on May 2, 2002. This center is located on the campus of the Northwest Sci-Tech University of Agriculture and Forestry (NWSUAF) in Yangling, China. The U.S. counterpart is located at the University of Arizona at Tucson, Arizona. ARS scientists from the National Soil Erosion Research Laboratory at West Lafayette, Indiana; and the National Sedimentation Laboratory at Oxford, Mississippi, are now actively cooperating with Chinese scientists to develop new methods to reduce soil erosion and sedimentation that will benefit both countries.
A special poster session was held at the annual Soil and Water Conservation Society meeting where 21 ARS scientists described recent advances in watershed and water quality management. Two keynote addresses, 15 technical papers, and 14 posters were presented at the American Society of Agricultural Engineers specialty conference entitled "Watershed Management to Meet Emerging TMDL Environmental Regulations."
Significant Accomplishments by Component
Agricultural Watershed Management
SALSA Speeds Solutions for Water-Scarce Southwest. The upper San Pedro River Basin of southeastern Arizona is perhaps best known for its lack of water. Recent estimates set this water debt at about 2.4 billion gallons a year for the entire basin, which extends from the state of Sonora in northern Mexico into the Gila River north of Tucson, Arizona. ARS scientists at the Southwest Watershed Research Center are leading an initiative, which includes nine Federal agencies, and four private organizations. This initiative, known as the Semi-Arid Land-Surface Atmosphere research program, or SALSA for short, is now in its sixth year. A major product from this program has been the Spatially Explicit Hydro-Ecological Model, called SEHEM, which has helped land managers deal with drought and water scarcity issues in Arizona and other parts of the desert Southwest.
From a Distance -- Remote Sensing of Planet Earth. The future of weather forecasting is rapidly changing. By the year 2008, we may have weather maps that can detect a flood in its infancy. It is all part of a "Soil-Moisture Observing System" envisioned by ARS scientists at the Hydrology and Remote Sensing Laboratory in Beltsville, Maryland, and scientists from the National Aeronautics and Space Administration (NASA). NASA is set to launch a satellite named "Aqua," which monitors the planetary water cycle. This accuracy of this system was tested by ARS scientists in airplane and satellite flyover campaigns in Arizona, New Mexico, Oklahoma, and Iowa. ARS researchers at the Hydrology and Remote Sensing Laboratory in Beltsville, Maryland, participated in a recent flyover campaign over the ARS Jornado Experimental Range in Las Cruces, New Mexico. An airborne laser altimeter provided a better understanding of the effect of plant canopy and landscape roughness on evaporative losses, soil water infiltration, surface water movement, and rangeland conditions. Other ARS scientists at the Southwest Watershed Research Center in Tucson, Arizona, have combined the traditional crop-yield models developed by USDA with climate data and data from satellite imagery to provide real-time forage prediction during the growing season. The research division of USDA's National Agricultural Statistics Service (NASS) and the Foreign Agricultural Service (FAS) have teamed up with ARS scientists at the Hydrology and Remote Sensing Laboratory in Beltsville, Maryland, to provide accurate reports of crop production for the United States and the world. Hopefully, these crop reports will include "real-time" soil moisture data in the near future from a combination of remotely sensed information and from the soil moisture and temperature monitoring network maintained by ARS and the NRCS on ARS experimental watersheds.
Attack on Giant Salvania. In ponds, lakes, and reservoirs from North Carolina to Hawaii, a stealthy invader called giant salvania is making an unwanted appearance. This free-floating fern has earned a reputation as one of the world's worst invasive aquatic weed. ARS scientists at the Invasive Plant Research Laboratory, Fort Lauderdale, the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida and Brisbane, Australia, have collected a dark-colored one-tenth inch-long weevil known as Cyrtobagous salvania, from another salvania species, Salvania minima, or common salvinia, growing in Florida. This biological agent has won kudos for holding giant salvania in check. Repeated tests have shown that the weevils attack only salvania and will not pester other plants. Recently, ARS received permission to release the weevil in Texas and Louisiana. In addition, ARS scientists at the Kika DE La Garza Subtropical Agricultural Research Center in Weslaco, Texas, have teamed up with Texas Parks and Wildlife Department to develop remote sensing technology for detecting and monitoring salvania infestations in south Texas. The result is color-infrared photos that positively identify giant salvania. These photos can then be used to pinpoint the release of the biological control agent and curb future outbreaks.
Texas SWAT Team Helps Clean World's Water. SWAT stands for Soil and Water Assessment Tool, a name that understates its practical benefits that farmers, ranchers, water quality managers, and legislators gain from using this decision support tool. SWAT was developed over the past 15 years by a team of ARS researchers from the Grassland, Soil and Water Research Laboratory, Temple, Texas. Recently, Texas legislators, water districts, and river authorities were impressed enough by results from the SWAT model, that they agreed to pay part of the costs for farmers to apply conservation measures that scientists using the SWAT decision support tool had demonstrated would work. Some of the newest attributes of the SWAT model include assessing potential nutrient, pesticide, and pathogen runoff into nearby streams, evaluating erosion-control measures to hold soil in place and slow its journey into water reservoirs; better nutrient management on agricultural land and on confined animal feeding operations to prevent algal blooms that impact aquatic life; and removal of juniper and mesquite brush to increase flow in drought-stricken areas in the Southwest.
Irrigation and Drainage Management
Water Management Reduces Methane Emissions from Rice. Rice is the primary food for about 50 percent of the world's population, and nearly all the rice is produced under paddy or ponded conditions. Rice may also have a major impact on global warming by contributing to the emissions of an important greenhouse gas: methane. In recent studies, ARS scientists in the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, conducted studies where the rice was flooded for different time periods. The studies showed that rice yields decrease when the plants are exposed to short, two-week droughts when the plants are flowering. However, when the researchers doubled CO2 levels, the plants maintained yields, used less water and endured a longer drought period. They also discovered that periodically draining the soil to aerate roots with atmospheric oxygen drastically decreases methane emissions. Controlling water table depths at the right time and not maintaining paddy rice fields year-long has international implications for maintaining rice production and at the same time reducing methane emissions from rice fields.
Raindrops on Cotton Cut Fiber Yield. It has been known for some time that rainfall can destroy pollen on cotton plants. Within only 30 to 60 seconds of encountering a drop of water, wet pollen grains swell up and pop open, dumping their contents prematurely and leaving the plant unpollinated and can significantly reduce cotton yields. ARS researchers from the Cropping Systems Research Laboratory in Lubbock, Texas, using this knowledge developed a new system call "drop socks" to avoid this problem. These scientists compared conventional overhead sprinkler irrigation fields with those watered by "drop socks" attached to sprinklers close to the ground. The drop socks minimize water spray on plants and dramatically reduce the yield losses associated with water-induced pollen death. Greenhouse tests showed a 55-percent loss in seed set after just one squirt of water. So, watering cotton plants from below through drip, furrow, or drop-socks irrigation should help ensure adequate pollination for optimal yields.
New Plants Shrug Off Salinity. Two new lines of salt-tolerant plants from ARS scientists at the U.S. Salinity Laboratory, Riverside, California, and the Forage and Range Research Unit in Logan, Utah, may prove to be a boom not only for wheat growers but also salt-laden wildland ecosystems. Salt tolerance is a prized trait in the irrigated wheat-producing regions of the American West, where irrigation can accelerate buildup of salts. The scientists are working to understand the complicated genetics of these plantsBincluding some that are relatives of wheat. These studies are key to making hardier and more nutritious feed grains and forages for livestock and wildlife such as deer, elk, and moose, as well as improved plants that could be used to revegetate rangelands, roadsides, burned sites, or erosion-prone slopes. The work has already attracted the attention of researchers and plant breeders throughout the United States and from several other nations as well.
Better Surface Water Quality, Dig Ditches. Drainage ditches are a common feature in agricultural landscapes. ARS researchers at the National Sedimentation Laboratory in Oxford, Mississippi, are attempting to define the benefits of properly-managed ditches in keeping water and pesticides from getting into water bodies. The ARS scientists found that properly located surface drains can trap 60 to 90 percent of commonly-used herbicides and insecticides carried in runoff water. Thus, ditches appear to be a simple, low-tech, inexpensive way to improve water quality.
Draining the Land Without Polluting the Water. Because field crops, like potted plants, languish when they are over-watered, proper drainage is an important aspect of successful farming. Nearly a third of the farmers in the Midwest rely on underground, or subsurface drainage to keep their plants healthy. ARS scientists at the Soil Drainage Research Unit in Columbus, Ohio, have shown that controlled subsurface drainage systems can increase corn and soybean yields and reduce nitrate losses by 30 to 40 percent. Under entirely different conditions, ARS researchers at the Soil and Water Research Unit in Baton Rouge, Louisiana, found that improvements in water quality with controlled drainage systems depend highly upon climatic conditions and that deep-chiseling is required to reduce both nitrate losses from surface and subsurface drainage systems. ARS scientists at the National Soil Tilth Research Laboratory in Ames, Iowa, found that wood chips and other types of biological materials can act as filters when placed in shallow drainage systems to decrease nitrate losses under controlled drainage practices. The biological filters increase denitrification once the water becomes ponded above the drainage tile. All of these locations are currently cooperating on new experiments that compare these new technologies with conventual drainage systems to continue reducing water pollution hazards.
Water Quality Protection and Management
Improved Land-Management Practices Protect Watershed Lakes. The Mississippi Department of Environmental Quality lists 581 streams, creeks, and rivers as impaired, largely with sediments, nutrients, insecticides, and herbicides. To help lower this number, ARS researchers at the National Sedimentation Laboratory in Oxford and the Application and Production Technology Research facility in Stoneville, Mississippi, are developing and testing conservation and weed-management practices to help agriculture do its share in improving the environment. They discovered that conservation tillage raises organic matter in the soil surface, which also increases the capacity of the soil to bind herbicides and reduce runoff into surface waters. They also found that vegetated filter strips helped reduce erosion by slowing runoff; increasing water infiltration; and minimizing loss of sediment, dissolved nutrients and herbicides. This means that filter strips are a viable technique to improve the soils natural ability to degrade herbicides before they have a chance to move into nearly lakes. These studies on three Oxford lake watersheds have shown farmers that a combination of conservation practices can improve water quality.
Grass Hedges to Catch Runaway Soil. Narrow, parallel rows of stiff-stemmed grass, planted along the contour of steep hills, can successfully halt soil erosion caused by flowing water. Although stiff-grass areas are a valuable conservation tool, little data on their hydraulic behavior is available. In the field and in flume facilities, ARS scientists at the National Sedimentation Laboratory in Oxford, Mississippi, and the Plant Science and Water Conservation Research Laboratory in Stillwater, Oklahoma, compared two types of stiff-grass hedges; switchgrass and eastern gamagrass. Switchgrass proved better adapted to flooding than gamagrass. Switchgrass held back sediment and water until the water ponded upstream to a depth of 1.4 to 1.6 feet. Switchgrass also recovered better than gamagrass from the previous years flooding.
Cleaning Up Runoff by Making Manure-Borne Pathogens Stay Put. Since many farmers use manure to fertilize their fields and pastures, they need an effective way to prevent harmful bacteria, like Escherichia coli 0157:H7 and Salmonella, from reaching the water supply. ARS scientists at Animal Waste Pathogen Laboratory in Beltsville, Maryland, have led a study on how such organisms can spread into the environment and whether grass buffer strips will filter them out. To date, grass buffer strips were far more effective at filtering out manure-borne pathogens then expected. The buffers stopped at least 90 percent of all the water runoff and almost no bacteria left the experimental field.
PAM Protects Against Pollutants and Pathogens. An environmentally friendly compound nabs nutrients and troublesome microbes before they can escape from farmer's fields and make their way to ponds, lakes, streams, or rivers. Known as polyacrylamide, or PAM, this powder can keep nutrients, such as the phosphorous in manure or fertilizers, from traveling beyond the farm in irrigation runoff. ARS scientists at the Northwest Irrigation and Soils research Laboratory in Kimberly, Idaho, also found that PAM helps keep diseasing-causing microbes or pathogens, like those in dairy manure, from being swept beyond the confines of farmyards or feedlots.
Working with Nature to Keep the Chesapeake Healthy. Thanks in part to improved agricultural practices over the past 30 years, the Chesapeake Bay is recovering, but more must be done to restore its health. A number of ARS locations are evaluating the effectiveness of riparian zones, consisting of grasses, forest vegetation, and combinations on there ability to reduce pollution from entering into surface waters and groundwaters. Recent findings from the Environmental Quality Laboratory at Beltsville, Maryland, show that nutrient inputs into wetland systems can increase growth of riparian vegetation, and this growth can represent a substantial increase in carbon storage capacity. The carbon storage also helps the plants and soil microorganisms to remove nutrients from the soil water within the wetland. However, macropores, which are created by animals burrowing through the soil or by cracks in the soil that occur in drier years, can be a problem. These large holes, or pipes, alongside the streams can act as a bypass route for groundwater nutrients and pesticides, such that these contaminant can travel directly beneath riparian zones an into streams.
Tiny Crustaceans Help to Measure Water Quality. The thought of tiny crustaceans in your water may seem disgusting, but ARS researchers at the National Sedimentation Laboratory in Oxford, Mississippi, hope to find a whole lot of healthy critters in their waters - especially if they're Hyalella azteca. That's because these crustaceans are a sign of good quality water. The 1/8-to-1/4 inch long crustaceans are commonly found in lakes, ponds, and streams throughout North America. Monitoring water quality through chemical and physical measures reveals the effects of improved conservation farming practices. However, the use of hyalella as a biological indicator will confirm whether these practices have actually improved the overall health of the ecosystem for fishing or swimming.