Location: Agroecosystems Management Research2013 Annual Report
Objective 1: Assess conservation practices and develop conservation planning tools that can improve agricultural water quality in the Midwest. Sub-objectives: 1) Develop and evaluate practices for reducing surface water contaminants in artificially drained landscapes; 2) Evaluate practices to reduce runoff and sediment losses from urban sites; and 3) Develop and evaluate tools to optimize placement of conservation practices within Midwest watersheds for improved environmental benefits. Objective 2: Determine the effects of climate, land use, and conservation practices on hydrology and water quality in agricultural watersheds. Sub-objectives: 1) Quantify hydrologic and water quality dynamics and their responses to changes in land use, conservation, and climatic conditions in Iowa watersheds; 2) Determine effects of landscape hydrology on soils and water quality in naturally and artificially drained landscapes; and 3) Map stream channel and bank movement in context with riparian land use and geomorphic setting to identify opportunities for restoring riparian ecosystems. Objective 3: Determine the fate and transport of pathogens and trace emergent compounds in agricultural soils and streams. Sub-objectives: 1) Determine transport pathways and environmental residence times of zoonotic pathogens associated with animal agriculture and the effects of management practices on those processes; 2) Determine transport pathways and environmental residence times of veterinary pharmaceuticals and the effects of management practices on those processes; and 3) Determine if exposure to trace antibiotic residues in soil or stream sediment affects the persistence of antibiotic resistant bacteria and resistance genes.
This project will conduct research to investigate the effects of agricultural management practices at field and watershed scales, the dynamics of watershed hydrology, and fundamental processes relevant to contaminant behavior in watersheds. Under the first objective, field studies will evaluate practices that can reduce loss of nitrate-nitrogen from cropped fields. These practices include resaturated buffers and bioreactors, practices that intercept tile drainage, and two practices that can reduce N loss to tiles, namely side-dressing of anhydrous ammonia and fall-planted cover crops. Bioreactor denitrification capacities will be assessed with microbiological assessments, and modeling studies will be conducted to extend experimental results on conservation practices to other areas of the Midwest. Research will be conducted to develop and evaluate watershed analyses to place conservation practices for improved water quality outcomes and determine how those strategies can be regionalized across the Midwest. Conservation needs also exist in urban environments and an experiment to determine how compost amendments can reduce urban runoff will be carried out. The second objective will be conducted in three Iowa watersheds, where stream monitoring will provide databases for watershed modeling studies, and for testing hypotheses about impacts of changes in climate and land use on water quality and hydrology. This research will be supported by efforts to identify field-scale patterns of hydrology and water quality, and better understand how new mapping techniques using Light Detection and Ranging (LiDAR) data can assist in understanding field hydrology, river corridor management, and targeting of conservation practices. The third objective will employ a mix of laboratory and field studies to evaluate environmental transport and residence times of pathogens and veterinary pharmaceuticals in soils and streams, and determine if exposure to trace antibiotic residues in soil or stream sediment affect the persistence of antibiotic resistant bacteria and antibiotic resistance genes. A breadth of watershed monitoring, controlled experiments in field and laboratory, and modeling techniques will be employed in the research. Publications, tools for conservation planning, and databases available to other scientists will be produced. Results are intended to enable agriculture to better manage water resources for multiple needs, particularly in the Upper Mississippi River basin.
Under Objective 1.1, research on an existing saturated buffer included nitrous oxide emissions and denitrification measurements. New sites were installed in Hamilton County, and at 15 sites across the Midwest in a collaborative effort. Research on denitrifying bioreactors continued through monitoring long-term (13 years) performance at one site, and a new bioreactor was initialized to operate at different flow rates and nitrate concentrations. Long-term research on cover crops was continued by measuring yield and nitrate in tile drainage in tilled and non-tilled corn-soybean rotations. Research on N-fertilizer timing is in its final year. This sub-objective includes modeling with the Root Zone Water Quality Model (RZWQM), which was tested for pesticide transport using field data from three states (MD, IA, NE). Results suggest RZWQM can help evaluate pesticide transport under varying soils and tillage treatments. Under Objective 1.2, new research on conservation in urban settings progressed; an experiment to evaluate compost addition was set up with plots on four urban sites. Soil water contents were monitored and runoff trials are planned. Two small grants were received to evaluate water quality benefits of rain gardens. Under Objective 1.3, conservation planning resources are being developed for watershed management applications, including tools to site a variety of practices (e.g., drainage water management, erosion control, wetlands, and riparian buffers). These tools have been combined into a planning framework that is being tested in Midwest watersheds. Under Objective 2.1, stream monitoring continued in three watersheds. Project milestones are being met, but resource limitations resulted in closure of three stream and two tile gages. An evapotranspiration model for Midwest crops is being calibrated with field data. Objective 2.2 evaluates landscape variation of soils and water quality; soil cores are being characterized for physical and chemical properties. Under Objective 2.3, stream bank positions and channel movement resulting from the 2008 flood in the South Fork Iowa River were mapped. Under Objective 3, methods for analysis of Salmonella, tylosin-resistance genes and antibiotics (tylosin, sulfamethazine) were improved. The methods were used in the South Fork Iowa River and Walnut Creek on a monthly basis. A new method called passive sampling with a Polar-Organic Chemical Integrative Sampler (POCIS) was begun. Laboratory calibrations were performed prior to deployment. The passive sampler may allow more sensitive and less costly monitoring of antibiotic residues in water. A cooperative field study on transport of tylosin and tylosin-resistance genes (erm genes) in tile-drainage from plots with and without swine manure was continued. In 2013, the analysis included two additional genes.
1. Development of watershed planning framework and a precision conservation toolkit. Individual conservation practices can effectively improve water quality if they are placed in appropriate locations, but the placement of a variety of practices needs to be considered in watershed planning. An ARS researcher in Ames, Iowa, has proposed that precision conservation techniques can be combined into a flexible framework that is appropriate for Midwestern landscapes and applicable to small (up to 30,000 acre) watersheds. The framework is based on a set of computerized landscape analyses that use newly available, detailed elevation data to identify where different types of conservation practices can be placed to improve water quality. The framework helps conservation planners and landowners develop a set of planning alternatives, which each map how a selected suite of conservation practices can be distributed to address key pollutant pathways in both surface and subsurface-drained landscapes. These scenarios provide the flexibility needed for local conservation planning decisions to be viable at the farm level, while being based on the best available technology and on local goals for environmental improvement. The framework is described in a recent feature article in the Journal of Soil and Water Conservation, and tests of this framework are being initiated in Iowa, Indiana, and Minnesota.
2. Drainage water management. The upper Midwest is the dominant source of nitrate to the Mississippi River which causes the hypoxic “dead zone” in the Gulf of Mexico. Most of this nitrate enters surface waters through the extensive network of agricultural, subsurface drain pipes underlying the region. Drainage water management is a potentially valuable practice for controlling water table levels in the soil and thereby reducing nitrate losses from artificial drainage. However, the practice had not been tested under Midwest conditions. Research by ARS scientists in Ames, Iowa, showed that during four years, drainage water management decreased tile flow volumes and total loading of nitrate by about 20%. Nitrate concentrations were similar to conventional drainage, so the benefit came from decreased drainage volumes. The decreased loss of water means greater amounts of water can be retained in the soil for crop uptake, and indeed small but significant yield increases were found under drainage water management for two years of soybean, which were the driest two years of the study. This research will be combined with studies in other Midwest states to then guide the United States Department of Agriculture-Natural Resources Conservation Service and state action agencies in determining to what extent drainage water management can impact local and regional water quality.
3. Tillage erosion by chisel plow. Tillage tools loosen soil which makes it susceptible to moving down slope under gravity. Over years of tillage, this process results in soil loss from the tops of hills, whereas at steeper mid-slope positions the most severe erosion problems are due to soil movement by runoff water. An ARS scientist in Ames, Iowa, showed that a twisted shank chisel plow did not loosen soil very deeply, so only soil near the surface was moved. Tillage erosion remains a major contributor to soil loss from hilltop areas in the field, resulting in lower organic carbon and fertility at the hilltops, and potentially decreasing crop yield and exacerbating nutrient leaching that can pollute receiving waters.
4. Prairie grasses and compost improve urban soil. Urban construction sites are compacted, which reduces growth of lawns and increases runoff and soil erosion. Research by an ARS scientist in Ames, Iowa, showed that soil was improved by mixing compost with the topsoil to 6-inch depth, and by planting buffalo grass and blue gamma grass. Compared with the control lawn, the improved site had better water holding capacity, eliminated sediment loss, and had more roots penetrating the dense subsoil. Native prairie grasses and compost benefit highly disturbed urban soils. This information can help developers minimize impacts of urban construction on runoff hydrology and sediment loss, reducing flooding and water-use impairments downstream.
Wang, L., Zhiqiu, G., Horton, R., Lenschow, D.H., Meng, K., Jaynes, D.B., Shao, M. 2012. An analytical solution to the one-dimensional heat conduction-convection equation in soil. Soil Science Society of America Journal. 76:1978-1986. DOI:10.2136/sssaj2012.0023N.
Kemper, D., Fouss, J.L., Jaynes, D.B., Dabney, S.M., Ihde, A., Meyer, D., Reicosky, D. 2013. Storm water management: Potential for lower cost & more benefits if farmers & municipalities cooperate on tile drainage. Journal of Soil and Water Conservation. 68(3):79A-83A.
Hatfield, J.L., Cruse, R.M., Tomer, M.D. 2013. Convergence of agricultural intensification and climate change in the midwestern United States: Implications for soil and water conservation. Marine & Freshwater Research. 64(5):423-435. DOI:10.1071/MF12164.
Brevik, E., Fenton, T., Jaynes, D.B. 2012. The use of soil electrical conductivity to investigate soil homogeneity in Story County, Iowa, USA. Soil Horizons. 53:5. DOI:10.2136/sh12-04-0013.
Jaynes, D.B. 2012. Changes in yield and nitrate losses from using drainage water management in Central Iowa, USA. Journal of Soil and Water Conservation. 67:485-494.
Logsdon, S.D. 2012. Depth dependence of chisel plow tillage erosion. Soil & Tillage Research. 128:119-124.
Helmers, M.J., Zhou, X., Asbjornsen, H., Kolka, R., Tomer, M.D., Cruse, R.M. 2013. Sediment removal by perennial filter strips in row-cropped ephemeral watersheds. Agriculture, Ecosystems and Environment. 41(5):1531-1539.
Moriasi, D.N., Rossi, C.G., Arnold, J.G., Tomer, M.D. 2012. Evaluating hydrology of the soil and water assessment tool (SWAT) with new tile drain equations. Journal of Soil and Water Conservation. 67(6):513-524.
Hernandez-Santana, V., Zhou, X., Helmers, M.J., Asbjornsen, H., Kolka, R., Tomer, M.D. 2013. Native prairie filter strips reduce runoff from hillslopes under annual row-crop systems, Iowa USA. Journal of Hydrology. 477:94-103.
Osmond, D., Gassman, P.W., Schilling, K., Kling, C.L., Helmers, M.J., Isenhart, T., Simpkins, W., Moorman, T.B., Tomer, M.D., Rabotyagov, S., Jha, M., Hoag, D., Meals, D., Arabi, M. 2012. Walnut Creek and Squaw Creek Watersheds, Iowa: National Institute of Food and Agriculture-Conservation Effects Assessment Project. In: Osmond, D.L., Meals, D.W., Hoag, D.L.K., Arabi, M., editors. How to Build Better Agricultural Conservation Programs to Protect Water Quality. Ankeny, IA: Soil and Water Conservation Society. p. 201-220.
Chigladze, G., Birrell, S., Kaleita, A., Logsdon, S.D. 2012. Estimating soil solution nitrate concentration from dielectric spectra using PLS analysis. Soil Science Society of America Journal. 76:1536-1547.
Zu, J., Ma, X., Logsdon, S.D., Horton, R. 2012. Short, multi-needle FDR sensor suitable for measuring soil water content. Soil Science Society of America Journal. 76:1929-1937.
Logsdon, S.D. 2013. Root effects on soil properties and processes: Synthesis and future research needs. In: Timlin, D., Ahuja, L., editors. Enhancing understanding and quantification of soil-root growth interactions. Madison, WI: Soil Science Society of America. p. 173-196.
Logsdon, S.D., Horn, R., Berli, M. 2013. Quantifying and modeling soil structure dynamics. In: Logsdon, S.D., Berli, M., Horn, R., editors. Advances in agricultural systems modeling 3. Madison, WI: Soil Science Society of America. p. 19.
Ma, L., Ahuja, L.R., Nolan, B., Malone, R.W., Trout, T.J., Qi, Z. 2012. Root Zone Water Quality Model (RZWQM2): Model use, calibration, and validation. Transactions of the ASABE. 55(4):1425-1446.
Qi, Z., Ma, L., Helmers, M.J., Ahuja, L.R., Malone, R.W. 2012. Simulating nitrate-nitrogen concentration from a subsurface drainage system in response to nitrogen application rates using RZWQM2. Journal of Environmental Quality. 41(1):289-295.
Meek, D.W., Hoang, C., Malone, R.W., Kanwar, R., Fox, G., Guzman, J., Shipitalo, M.J. 2012. Rational polynomial functions for modeling E. coli and bromide breakthrough. Transactions of the ASABE. 55:1821-1826.
Fox, G., Marvin, M., Guzman, J., Hoang, C., Malone, R.W., Kanwar, R., Shipitalo, M.J. 2012. E. coli transport through surface-connected biopores identified from smoke injection tests. Transactions of the ASABE. 55:2185-2194.