Introduction

A program planning workshop for the Soil Resource Management National Program was held in Denver, Colorado, February 23-26, 1999. Approximately 150 participants attended the workshop, including producers, commodity group representatives, agricultural industry representatives, representatives of nongovernmental organizations, university scientists, and scientists and administrators from ARS and other federal and state agencies. At the workshop customers, stakeholders, and partners provided input concerning their problems and needs relative to soil resource management. Research activities within the program were organized into five component areas: (1) soil conservation and restoration, (2) nutrient management, (3) soil water, (4) soil biology, and (5) productive and sustainable soil management systems.

Writing teams composed of ARS scientists and members of the National Program Staff (NPS) were formed for each program component to develop planning documents that will provide a framework for ARS research in this area over the next 5 years. The writing teams used input from the workshop, their own knowledge of the subject matter area, and input from ARS scientists and cooperators to identify researchable problems that need to be addressed. This information was incorporated into a action plan that provides background information about the overall component and explains why a particular research area is important, how it will be addressed, and the benefits of conducting the research. These documents can be viewed on the ARS home page.

The implementation planning phase of this national program will now begin. Improved communication and research coordination among ARS scientists and their cooperators is an important goal of the planning and implementation process. Scientists in each of the five components will interact among themselves and with NPS to identify specific areas in which they will conduct research, locations and projects involved, anticipated products or information generated by the research, and timelines and milestones for measuring progress toward achieving the goals of the program. New research project plans will then be developed by each laboratory associated with the Soil Resource Management National Program based on problem areas and goals in the component actions plans. All project plans associated with this national program will be evaluated for scientific quality by an external peer review panel in December 2000.

Significant Accomplishments by Program Component in FY 1999

Soil Conservation and Restoration

Soil degradation, through human activities and natural forces, has reduced the productivity of our soils and damaged adjacent ecosystems. Soil degradation can result from accelerated soil erosion, loss of vegetative cover, oxidation of soil organic matter, and impairment of other soil physical, chemical, and biological properties. Worldwide, erosion by water, wind, tillage, and irrigation remains a major cause of soil degradation and a primary environmental concern. Erosion prediction technology is widely used by federal, state, and local agencies and private organizations to assess the degree of soil erosion and to predict appropriate conservation practices to reduce erosion. ARS scientists at Oxford, Mississippi, have recently improved the accuracy, utility, and ease of use of the Revised Universal Soil Loss Equation (RUSLE). The new version of RUSLE, known as RUSLE2, has been released to the Natural Resources Conservation Service (NRCS) for their evaluation and implementation. RUSLE2 is much easier to use than the previous version and will allow conservationists at the NRCS local and field office level to develop more comprehensive conservation plans for land users.

ARS scientists are conducting research to overcome natural and man-induced soil physical property limitations such as soil compaction, poor soil structure, and surface soil crusting. Surface application of soil amendments, such as polyacrylamide (a water-soluble polymer) and high gypsum coal combustion products resulted in improved soil aggregate stability (West Lafayette, Indiana). Enhanced soil aggregate stability improved water infiltration and reduced soil surface sealing, thus reducing soil erosion. In addition to erosion benefits, grass seedling establishment was improved on steep slopes and crop yields were increased. A 5-year study at Stoneville, Mississippi, demonstrated that deep tillage (subsoiling) of clay soils in the fall significantly increased soybean yield and increased net annual returns by $29/acre to $87/acre when compared to disk tilled production systems. Fall subsoiling removed limitations to root growth, improved soil moisture relationships, and avoided tillage operations during wet periods in the spring. Deep paratillage at the start of the growing season disrupted root restrictive layers in hardpan soils of the southeastern United States and resulted in increased yields of double cropped winter wheat and spring-planted soybeans compared to conventional tillage systems (Florence, South Carolina).

Nutrient Use Efficiency

Since the 1950s, the philosophy and practices governing nutrient management have changed from on-farm recycling of nutrients using animal or green manure to use of concentrated chemical fertilizers. However, fertilizer use-efficiency is commonly less than 50 percent in many agricultural systems. Application of excessive amounts of fertilizer or manure is one reason agriculture is the largest nonpoint source of pollution to surface and groundwater. Economic use of renewable nutrient sources and improved nutrient use efficiency in agricultural systems are problems that must be addressed to reduce input costs and protect the environment. Research is needed to understand nutrient fate and transformations in soil so that management practices can be developed for sustainable production while protecting soil, water, and air.

Low nitrogen use efficiency by crops can contribute to increased nitrate movement to groundwater. ARS scientists at several locations are developing management practices to increase nitrogen use efficiency, thus protecting groundwater quality. ARS researchers at Kimberly, Idaho, determined that placing nitrogen fertilizer on one side of the corn row and irrigating the other side increased nitrogen uptake and reduced residual soil profile nitrogen while maintaining yields. Fertilizer recovery efficiency in sunflower production was doubled by banding liquid nitrogen fertilizer by the seed compared with broadcasting nitrogen fertilizer on the soil surface (Akron, Colorado). The Nitrogen Leaching Economic Analysis Package (NLEAP) model, used by ARS, NRCS, and universities to evaluate the effect of agricultural management practices on nitrogen and water budgets has been upgraded (Ft. Collins, Colorado). Tests of the model in farmers? fields in the San Luis Valley of Colorado indicated that rotations of small grain crops with vegetables can mitigate nitrogen losses to groundwater by scavenging nitrogen that has been lost below the shallower root systems of vegetable crops such as lettuce, potatoes, and spinach. This study demonstrated that small grain winter cover crops increase the nitrogen use efficiency of the entire system and reduce nitrate leaching to groundwater.

ARS scientists at St. Paul, Minnesota, demonstrated that flue gas desulfurization residue, a by-product of coal combustion, can be used as a fertilizer source for alfalfa production. They conducted field experiments to document the fate of leachable elements in the residue such as sulfur, boron, and molybdenum after the residue was land-applied to correct soil acidity and supply essential plant nutrients for alfalfa production. Their research demonstrated that the coal combustion residue was an economical source of nutrients for alfalfa production and posed no threat to the food chain or environmental quality. State and federal regulatory officials can use this information as they establish rules and guidelines for the beneficial use of these materials in agricultural systems.

Soil Water

Water is the most limiting soil factor for crop growth and yield in most agricultural soils, accounting for approximately 80 percent of crop yield variability. Soil water, directly or indirectly, affects most soil physical, chemical, and biological properties and processes. It also functions as a transport medium for chemicals and microorganisms into, through, and below the soil profile. Most crop production problems associated with soil water relate to its supply and availability; infiltration adequacy and timing; and prevention, elimination, or mitigation of soil water excesses. Some soil water management considerations are similar regardless of cropping systems. Others vary considerably, especially between rain-fed and irrigated agriculture. Characterization of soil properties affecting soil water remains difficult. This slows progress on other fronts, especially development and validation of new soil water concepts, theories, and models. Research in this component area will address these and other issues associated with soil water management.

Reliable estimates of soil hydraulic properties are needed in many hydrologic, subsurface pollution, and crop production studies, but these properties are very difficult to measure rapidly and accurately in the field. Scientists at Riverside, California, have made great progress in predicting unsaturated soil hydraulic properties (water retention, hydraulic conductivity) from more readily available soil survey type data such as soil texture and bulk density. They also have established a large database of unsaturated soil hydraulic properties. This information can be used by agencies such as NRCS, the U.S. Environmental Protection Agency, the Department of Energy, the National Aeronautic and Space Administration, and the Army Research Office to predict the transport of nutrients, trace elements, and organic contaminants from the soil surface to groundwater. In addition, soil hydraulic properties can be used to estimate heat and mass transport across the soil surface to simulate the extent and effects of regional and global climate change. ARS scientists at Oxford, Mississippi, have developed tools to determine soil properties needed to assess wetland management practices. This information has been transferred to the NRCS Wetland Science Institute where they will now be able to use this information in models to determine the effectiveness of wetland systems under a variety of conditions.

Soil Biology

The living portion of the soil consists of plant roots and great numbers of remarkably diverse living organisms that are partially to totally invisible to the naked eye. Soil microorganisms can account for 10 percent or more of the weight of soil organic matter, and over 10,000 species of microorganisms can exist in a single gram of soil. Although the importance of these organisms is generally accepted, a greater understanding of their role in soil physical, chemical, and biological properties and processes will be needed to manage this resource for the benefit of agricultural and other land uses. Research also will be needed to understand the basic ecology of soil organisms in bulk soil as well as in close proximity to plant roots and seeds. Other areas that will require investigation include interactions between soil management practices and soil organisms; the role of soil organisms in controlling plant diseases, plant pests, and weeds; and the role of soil organisms in degradation of pesticides and other synthetic and natural toxins.

ARS scientists at Wyndmoor, Pennsylvania, are developing methods to reestablish mycorrhizal fungi in soil where populations of the natural biota have been reduced by overcultivation and indiscriminate use of pesticides. They have found a way to produce large quantities of spore inoculum and have demonstrated the efficacy of the inoculum to increase yield, size, and vitality of horticultural plants. Successful introduction of beneficial soil fungi into production systems can lower costs and enhance soil quality. Mycorrizal fungi also have been shown to release insoluble substances that coat soil particles and contribute to the formation of stable soil aggregates (Beltsville, Maryland). Improved aggregate stability creates more favorable conditions for plant growth by enhancing water and air movement through soil. The insoluble substances released by the fungi also contribute to soil sequestration of carbon, thus reducing carbon dioxide release to the atmosphere.

A bacterial strain has been isolated to degrade the organophosphate coumaphos used for tick control in cattle. A 15,000-liter field-scale biofilter unit for treating coumaphos dip waste was designed, constructed, and field tested at an Animal and Plant Health Inspection Service (APHIS) facility in Mission, Texas. Field trials on 11,000-liter batches of dip showed that the unit reduced coumphos levels in the dip by a factor of 200 in 15 days. A field trial at two APHIS dipping vats showed that maintaining a pH lower than 5.5 through the use of a phosphate fertilizer effectively prevented the accumulation of toxic potasan in those vats. This will extend the useful life of the pesticide coumphos in the vats, reducing pesticide costs and reducing the amount of waste that is generated.

Productive and Sustainable Soil Management Systems

Major advances in agriculture have been made through improvements in plant genetics; nutrient and water management; tillage practices; weed, insect, and pathogen control; and planting and harvesting equipment. These advances have not come without environmental and economic costs. Our focus in this component area will be to develop more sustainable soil management practices by using a systems approach to integrate principles of soil biology, chemistry, and physics into management practices that will optimize land use and be readily adopted by producers. This approach will be characterized by a coordinated effort to balance all inputs and outputs to optimize productivity, profitability, and sustainability, while minimizing environmental impacts. Research in this area will include developing environmentally sound, economically viable, and innovative crop rotation, cover crop, and residue management strategies; providing site-specific soil management practices to optimize soil biological, chemical, and physical properties and processes; and determining how soil management affects soil quality.

More than 25 percent of the cotton produced in the southeastern United States is grown on highly erodible land. Improved production practices are needed to increase profitability and reduce soil erosion. ARS scientists at Auburn, Alabama, and their cooperators have demonstrated that ultranarrow row production using a high-residue conservation tillage system increased cotton yield on marginal soils up to 60 percent when compared to conventionally tilled standard row width cotton. Producers in the southeastern United States are rapidly adopting this new technology. Acerage in ultranarrow row cotton production has increased from 3,500 acres in 1997 to approximately 200,000 acres in 1999.

Approximately 20 million acres in the central Great Plains are currently in a wheat fallow rotation. Unfortunately, fallow degrades soil quality, promotes soil erosion, and strains economic resources. ARS scientists at Akron, Colorado, and their cooperators have developed alternative rotations that can replace wheat-fallow. They found that rotations such as wheat-corn-proso millet-fallow or wheat-corn-proso millet could double land productivity relative to a winter wheat-fallow rotation. These alternative rotations will allow producers in the central Great Plains to increase profitability, while improving soil quality and control of weeds.

An analysis of 15 years of soil, plant, and drainage water data, collected from 36 1-acre plots in northeastern Iowa, showed that with moldboard plowing, chiesel plowing, ridge-tillage, or no-tillage, most of the nitrogen applied to grow corn during those years could be accounted for by grain removal (45 percent), loss in the drainage water (12 percent), or increases in soil organic matter (43 percent). This means that adopting tillage practices that preserve or increase soil carbon (organic matter) can prevent loss of residual nitrogen to surface or ground water resources while improving soil quality by increasing water­and nutrient­holding capacity.