Agricultural scientists work to sustain the environment

Linda Benedict, Brown, William H.  |  8/18/2009 12:55:35 AM

Gary A. Breitenbeck teaches the science of creating compost at each of the LSU Agricultural Center’s Compost Facility Operator Training Schools. Under a tent at the facility, he sets up a mini chemistry lab and teaches the students to use various instruments and measure oxygen, moisture content, and other important compost features. (Photo by Mark Claesgens)

Photo of William Brown

William H. Brown

This issue of Louisiana Agriculture is devoted to Louisiana Agricultural Experiment Station (LAES) research programs that focus on the beneficial recycling or reuse of organic wastes. The outcomes of these programs will provide alternatives to the land filling of many municipal and industrial wastes and will be a positive force in improving and sustaining Louisiana’s environmental quality. In addition to these programs, the LAES conducts an array of research activities that have as their broad objectives the improvement of Louisiana’s environment.

The word “environment” means many different things to different people. To some it stirs visions of clear, pristine streams and lakes; to others vistas of forests or prairies; to still others, clean fresh, mountain air. To agriculturalists, who produce food and fiber for the citizens of the United States and a substantial part of the rest of the world, a quality environment means acres of productive soil, clean air and an adequate supply of quality water for irrigation, for livestock consumption and for human use. All these visions of a quality environment are, by themselves, both accurate and incomplete. To complete the picture, one must appreciate the array of agricultural research conducted in Louisiana and at other agricultural experiment stations across the country. Much of this research is not commonly thought of as “environmental,” yet it affects the quality of our air, soil and water resources.

Agricultural scientists were among the original environmentalists. For most of this century, agricultural researchers have recognized the importance of sustaining the natural resource base–air, soil and water–on which agricultural production relies. For example, the 1930s saw the initiation of widespread programs at land-grant universities and at the federal level to reduce soil erosion, to keep the soil covered with vegetation and to improve drainage to enhance soil productivity. Through the ensuing years, many research programs have been conducted to provide information for improving the “environmental friendliness” of food and fiber production and processing.

The stage was set for contemporary LAES environmental research programs when “Focus 2000: Research for the 21st Century,” a strategic plan for the LAES, was adopted in 1990. One thrust of this plan was to protect the environment by “developing production systems that protect the soil and minimize the need for fertilizer, water, tillage, and other inputs...” Adoption of Focus 2000 led to establishment of the Soil, Water and the Environment Research Advisory Committee (RAC). It provided LAES researchers a forum for exchanging information on environmental programs and for forming new collaborations with colleagues.

One outcome of the Soil, Water and Environment RAC was sponsorship of an environmental conference in 1995. This conference included LAES research presentations on land use management, waste management, forestry, pest management, water quality and conservation tillage and presentations from numerous state and federal agencies including the Louisiana Department of Environmental Quality, the Barataria-Terrebonne National Estuary Program, the Natural Resources Conservation Service and others. Conference participants set the stage for the LAES environmental research programs conducted in the remainder of the 1990s.

Many of the LAES environmental research programs can be broadly grouped as follows: conservation tillage, management of wastes and residues for beneficial uses, water quality, integrated pest management, and nutrient management.

Conservation tillage  

LAES programs in conservation tillage for cotton production on Macon Ridge soils demonstrated not only that cotton could be successfully produced with little or no tillage, but, when combined with a winter cover crop, soil erosion could be reduced by up to 85 percent, soil organic matter could be slowly but steadily rebuilt, and that nitrogen fertilizer requirements could be stabilized at about 70 pounds or less per acre, depending on the cover crop grown. This pioneering research, along with advances in herbicide technology, paved the way for practical conservation tillage production systems (sometimes called “stale seedbed” systems) now widely used on Louisiana cropland, resulting in major soil erosion reductions.

Another area in which LAES scientists have pioneered has been in conservation tillage systems for rice in southwest Louisiana. Although still being developed and refined, conservation tillage promises to offer rice producers a practical way of producing rice while reducing the sediment load of the water leaving their fields.

Waste management

Waste management programs deal with the manures and residues that result from animal production and processing and the development of methods to beneficially use the solid wastes that originate from both agricultural operations and urban activities. A program is under way to determine the extent to which dairy manures and related fecal coliform indicator organisms move into water bodies when irrigated onto pastureland in “no discharge” systems. Further knowledge about how to minimize the environmental impacts of dairying is vital for Louisiana’s economically important dairy industry in the environmentally sensitive Lake Pontchartrain drainage basin.

Another area of intense research activity deals with establishing benchmarks for poultry litter disposal in north Louisiana. Poultry litter, a byproduct of broiler production, is a valuable source of nutrients for pasture and forest lands, but excessive application can overload the soil’s ability to assimilate phosphorus. And, if allowed to move into water bodies, phosphorus could cause eutrophication problems. Several LAES studies are under way that will define safe application levels, the fertility value and alternative beneficial uses for poultry litter.

Many agricultural and urban residues can be treated by composting to reduce volume, eliminate odors and neutralize undesirable components. The resulting compost can be incorporated into the soil to enhance soil structure and plant growth. LAES scientists participate in the LSU Ag Center’s Organic Recycling Center to better understand and use the composting process and its products and to train people in the science of composting. The LSU Ag Center has conducted nine one-week programs which have trained about 150 people from 29 states and three countries in the proper techniques of composting organic residues for beneficial uses.

Water quality  

Water quality is affected by nearly all the programs described here. Some research studies cut across many crops and soil types. These studies provide basic information on how precipitation moves off the land, through the soil and what it carries with it. This information is fundamental to our understanding of how water transports nutrients and chemicals through the soil and how rainfall or irrigation water can be managed to improve both crop production and the environment.

LAES soil scientists and agricultural engineers have teamed with USDA researchers to determine the complex mechanisms by which water moves through Louisiana’s alluvial soils, how rapidly it moves and the extent to which it transports certain nutrients and esticides. Other studies have shown that subsurface drainage can reduce soil erosion and improve water discharges into drainage systems. Studies of corn production over five years showed that subsurface drainage reduced soil loss by 30 percent, nitrogen loss by 20 percent and phosphorus loss by 36 percent. A similar nine-year study with soybeans showed 48 percent less soil loss, 39 percent less nitrogen loss, 35 percent less phosphorus loss and 36 percent less potassium loss.

Water table management is a technology that uses underground tubes to drain excess water from fields to prevent water logging damage to crops during wet weather and also to irrigate from below the surface during drought. Future cooperative studies with USDA scientists will focus on how water table management can enhance crop production (sugarcane especially) while improving the quality of the water drained from the field.

It is important, both environmentally and economically, that nutrients not be applied to producers’ fields in excessive amounts that cannot be assimilated by plants.

Integrated pest management

Integrated pest management (IPM) refers to the integrated use of all appropriate methods to control agricultural pests such as weeds, insects, diseases and nematodes. IPM systems employ judicious use of pesticides along with cultural practices, genetic resistance and other available means to reduce dependence on pesticides. Reduced pesticide usage is based on careful scouting and precision application methods. Although most pesticides used today are much less toxic to non-target organisms and used in much smaller quantities (ounces rather than pounds per acre), the end result of IPM is that relatively fewer pesticides are introduced into the environment. Some crops are now resistant to selected herbicides or to certain insect pests because of recent advances in plant genetic engineering. The fruits of several decades of intensive molecular biology research have provided LAES entomologists and weed scientists with additional tools to develop practical production systems that use these special plants to combat competing or damaging pests while minimizing pesticide use.

Nutrient management

Nutrient management, actually one of the oldest of the agricultural sciences, determines the need for supplementing the soil’s natural fertility with the appropriate types and amounts of nutrients to achieve the genetic potential of today’s improved seeds. It is important, both environmentally and economically, that nutrients not be applied to producers’ fields in excessive amounts that cannot be assimilated by plants.

Nutrient management research starts with LAES agronomists who determine the nutrient needs for the many crops produced on the diverse soil types of Louisiana. Soil scientists determine nutrient interactions and availability in the various soil types and textures. The Soil Testing Laboratory provides individual field analyses that determine the nutrients that need to be added and their amounts for specific crops and locations. This information is provided to extension agents so they can make specific fertility recommendations to farmers. Finally, new technologies are now being investigated, usually called “precision farming systems,” that will allow variable, on-the-go precision nutrient applications within fields based on intensive soil testing, crop production history and other pertinent factors.

Taken together, today’s producers are armed with an array of science-based data, sophisticated testing services and the most modern technology to enable them to apply only the required nutrients in only the needed amounts at only the proper locations for optimum crop performance.

Other activities

Integrating the best science with economic constraints and environmental concerns is challenging. In 1993, LAES scientists, in cooperation with the Louisiana Cooperative Extension Service, farmers representing the Louisiana Farm Bureau Federation, and representatives of state and federal agencies such as the Natural Resources Conservation Service (NRCS), Louisiana Department of Agriculture and Forestry (LDAF), Louisiana Department of Environmental Quality (LDEQ), Department of Natural Resources (DNR), Agricultural Research Service (ARS) and others launched an effort to integrate the best information available into a series of “best management practices” or BMPs. The BMPs cover all of the major plants and animals produced in Louisiana. These BMPs were completed and disseminated to producers, research scientists, extension faculty and regulatory agencies in 1996. They are undergoing revision and updating to provide producers with the best practical options for environmentally sound farming.

The LAES also participates in cooperative multi-state and national activities to better understand environmental changes and impacts. Many of the previously described activities are conducted in collaboration with research colleagues in other states through USDA’s Multi-State Research Program.

Two LAES research stations, Southeast and Iberia, have operated sites for the National Atomospheric Deposition Program (NADP) since the early 1980s. This program, supported in part by state agricultural experiment stations nationwide, has provided measurements of precipitation acidity and atmospheric nutrient deposition at more than 200 sites for 20 years. The NADP is now developing a national mercury deposition network, and the LAES will provide two monitoring sites, the Hammond and the Sweet Potato research stations, that will be operated by the Louisiana DEQ. The LAES also operates a network of meteorological recording sites at the LAES research stations called the Louisiana Agriclimatic Information System (LAIS). The LAIS provides scientists with an extensive database of the state’s recent meteorology in support of their research programs.

Future food demands  

There are many other equally important programs that could be discussed such as forest sustainability, wildlife and fisheries programs, marsh revegetation research and others. I hope readers will feel free to contact me or any LAES scientist for further information.

The presence of human beings affects the “natural” state of things. The earth’s environment has never been static; it has been subject to both dramatic upheavals and slow, evolutionary changes, but it has never remained the same. Our crowded cities and sprawling suburbs have environmental impacts. Likewise, the production of food and fiber for a growing world population will have environmental consequences. Agriculture and cities must co-exist, however, if society, as we know it, is to continue and to prosper. Some forecasts suggest that the world’s food demand will triple over the next 40 years. To meet that demand, we must continue to invest in science and technology so that we can learn how to use reasonable and effective measures to blend sustainable economic growth with acceptable environmental impacts.

William H. Brown, Associate Director, Louisiana Agricultural Experiment Station, LSU Agricultural Center, Baton Rouge, La.

(This article was published in the spring 1999 issue of Louisiana Agriculture.)

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