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United States Department of Agriculture

Agricultural Research Service


Location: Cropping Systems and Water Quality Research

2013 Annual Report

1a. Objectives (from AD-416):
Problems to be addressed through this agreement include the following four areas: 1. Improving our understanding of the aggregate effects of conservation practices at the watershed scale; 2. Improving our ability to select and place conservation practices on the landscape for maximum effectiveness; 3. Improving conservation practices to better protect water resources; and 4. Maintaining the effectiveness of conservation practices under changing climate and land use.

1b. Approach (from AD-416):
Improving our understanding of the aggregate effects of conservation practices at the watershed scale: 1. Field studies to develop remote sensing tools to better evaluate cover crop performance (CB/ACP). 2. Develop models/decision support tools to assess the effectiveness of cover crops (CB/ACP) and other BMP’s (All) at the watershed scale. 3. Enhance the landscape version of SWAT to better represent field-to-basin scale processes (All). Improving our ability to select and place conservation practices on the landscape for maximum effectiveness: 1. Develop mapping techniques for placing specific practices within watersheds based on terrain and soils data. 2. Develop methods of terrain analysis for improved mapping of soil wetness in glacial terrain. 3. Validate the CEAP National Assessment conducted with SWAT at multiple scales. 4. Assess and compare the trade-offs of no-till adoption, and support the development of nutrient management recommendations for water quality protection, at the watershed scale. Improving conservation practices to better protect water resources: 1. Quantify nutrient management effects on water quality at field and watershed scales. 2. Watershed scale studies to systematically validate phosphorus site assessment tools in support of NRCS 590 (nutrient management) standard. 3. Watershed scale assessment of combined conservation practices. Maintaining the effectiveness of conservation practices under changing climate and land use: 1. Use reservoir sedimentation, land use change, and climate information to anticipate future reservoir sedimentation and needs for additional conservation under changing climate. 2. Enhance SWAT model routines for urban landscape BMPs. 3. Apply erosion (WEPP, etc.) and water quality (WEPP-WQ, etc.) models to catchments ranging from field- to farmsize and watershed scale, to assess the impacts of current and alternative land management systems and conservation practices under current and future climates.

3. Progress Report:
Research being conducted in the ARS Croplands CEAP Watershed Assessment Study are carried out under the respective project plans at the individual locations. Watershed leaders and National Program Leader met monthly via teleconference and held their annual meeting July 24, 2013, during the American Society of Agricultural and Biological Engineers Annual conference in Kansas City, following an ARS-led symposium on Opportunities and Challenges in Long-term Research Watersheds. ARS National Program Leader gave a brief introduction of a Water Environment Research Foundation (WERF) initiative to expand their current stormwater Best Management Practices (BMP) database idea to include agricultural BMPs, and led discussion about how ARS might participate in that initiative. Each watershed presented overviews of recent research findings and current year research activities. ARS researchers at University Park, Pennsylvania: Two new versions of the Soil Water Assessment Tool (SWAT) improve representation of hydrology typical of the upland reaches of the Chesapeake Bay watershed and improve representation of phosphorus cycling. ARS researchers at University Park tested the new versions of SWAT and demonstrated that they better match observed data than convention versions. These improved models are being used in regional and national projects to validate the Phosphorus Index. New databases tracks ten years of management on over 200 fields in the Mahantango Creek watershed. Scientists at University Park have developed a spatial database of crop, tillage, fertilizer and pesticide management for fields within the WE-38 experimental sub-watershed. This database will be used to evaluate trends in management practices as well as to examine links between agronomic practices and water resources. Comprehensive soil sampling offers insight into long-term effects of crop and tillage management. Scientists at University Park sampled soils in more than 200 fields for which long term management data were available. This effort is intended to offer insight in to the effects of tillage and cropping system impacts on soil phosphorus and organic matter accumulation. ARS researchers at Kimberly, Idaho: Sediment and nutrient balances for the watershed show that about 70 lb/a of sediment was deposited in the watershed annually from 2005 to 2008 compared to losing 450 lb/a of sediment in 1971. From 2005 to 2008, diverting irrigation water into the watershed removed about 7000 tons of sediment, 23 tons of dissolved phosphorus, and 35 tons of total phosphorus from the Snake River on average each year. However, the watershed contributed almost 1000 tons of nitrate-N annually to the Snake River. ARS researchers at Oxford, Mississippi: Work under this cooperative agreement includes routine site maintenance and data collection activities. We continue to collect data at nine supercritical flumes within Goodwin Creek. Parameters measured include stage, discharge, precipitation, and sediment concentration. To improve resolution of low flow conditions, additional pressure transducers have been fitted into the flumes to supplement acoustic stage measurements. A turbidity gauge has been successfully deployed at station #2 and its readings will be calibrated against sequential fine sediment samples collected there. We continue to monitor a network of 27 rain gauges. We now need to examine all gauge data within 30 days and report anomalies to the field team. We are systematically working backward through the historical data in order to improve the completeness and accuracy of the record. We continue to maintain and support the NRCS Soil Climate Analysis Network and NOAA Surface Radiation Network weather stations located at site 50. To supplement measurements taken at this site, we have entered an agreement with the University of Arizona to install and maintain a new soil moisture sensor at site 50. The Cosmic-ray Soil Moisture Observing System or COSMOS sensor is designed to measure fast neutrons in the atmosphere. The abundance of fast neutrons is proportional to soil moisture. This method provides average soil moisture over an approximately 34 hectare area. To improve understanding of management practices at the field scale, we developed an SCA with the North Mississippi Resource Conservation and Development Council (NMRCDC). We jointly developed and administered a questionnaire of landowners to quantify the inputs of fertilizer and pesticides and the output of crop and animal yields. The NMRCDC collected the records, removed personally identifiable information, and compensated landowners for their information. Questions were designed to provide land use information suitable for inputs to computer based runoff and erosion models including crop rotation, tillage, amendments, grazing, and forestry practices details. During 2013, three new edge-of-field sampling sites went on-line. One site drains a planted pine plantation, one site drains cropland, and one site drains pasture. Observations of macro-pore and pipe flow in the pasture site prompted researchers to add three additional monitoring sites within the 7 acre pasture site and to conduct tracer studies to determine the connectedness and transmission speeds of active pipes. ARS researchers at Tifton, Georgia: Studies of hydrology and water quality at nine long-term stations (weirs) in the Little River Watershed were continued. Hydrology measurements include stream stage and computed flow. Flow proportional water quality samples are taken bi-weekly and stored under refrigeration in the field. Water quality measurements include nitrate plus nitrite-N, ammonium-N, total N, ortho-P, total P, chloride, and current use pesticides at selected sites. Bi-weekly readings of pH, dissolved oxygen, temperature, and oxidation reduction potential are also taken at the time of sample collection. Data on water withdrawal permits in the Little River Watershed have been obtained from the Georgia Environmental Protection Division/Watershed Protection Branch. The permit data will be mapped to specific locations in the watershed, typically either a well or farm pond. These data will be used to estimate both the total import of water to the surface (from ground water) and the loss of potential streamflow (from farm ponds).

4. Accomplishments
1. ARS researchers at Ames, Iowa: 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. (Log# 293615) Tomer, M.D., S.A. Porter, D.E. James, K.M.B. Boomer, J.A. Kostel, and E. McLellan. 2013. Combining precision conservation technologies into a flexible framework to facilitate agricultural watershed planning. Journal of Soil and Water Conservation 68(5):113A-120A. (Log # 293615)

2. ARS researchers at Ames, Iowa: 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 (DWM) 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, IA showed that during 4 years, DWM 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 significant under DWM for 2 yr 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 USDA-NRCS and state action agencies in determining to what extent DWM can impact local and regional water quality. (Log# 275237) Jaynes, D.B. 2012. Changes in yield and nitrate losses from using drainage water management in central Iowa, United States. Journal of Soil and Water Conservation. 67(6):485-494. (Log # 275237)

3. ARS researchers at Ames, Iowa: 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 researcher in Ames, IA, showed that a twisted shank chisel plow did not loosen soil very deeply, so only soil near the surface became 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 causing nutrient leaching that can pollute downstream receiving waters. (Log # 278243) Logsdon, S.D. 2013. Depth dependence of chisel plow tillage erosion. Soil and Tillage Research 128:119-124. (Log # 278243)

4. ARS researchers at Beltsville, Maryland: Using remote sensing to improve tracking of agricultural conservation practices. The planting of winter cover crops is a critical agricultural conservation practice in the Chesapeake Bay watershed, and cover crops have been shown to be effective in reducing nutrient and sediment losses from farmland. However, the success of wide-scale conservation programs to promote winter cover crops has been hampered by the difficulty of tracking winter cover crop performance over large spatial areas. ARS researchers at Beltsville, MD, have been working in partnership with the U.S. Geological Survey and the Maryland Department of Agriculture (MDA) to map and report winter cover crop performance on working farms. Data integration is used to match satellite-based measurements of biomass, cover crop management, and crop type to evaluate the on-farm cover crop performance at the watershed scale. Results of a five-year analysis of winter cover crop performance in Talbot County, MD, demonstrate significant improvement in wintertime groundcover linked to increased farmer participation in conservation cost-share programs, and can be used isolate successful cover cropping strategies. Scaling this work throughout the State of Maryland, and neighboring Chesapeake Bay jurisdictions, will provide information that can be used by farmers and conservationists to support tracking and adaptive management of agricultural conservation practices for water quality protection.

5. ARS researchers at Beltsville, Maryland: Assessing the landscape connection of wetlands. The connection of wetlands to the local stream network influences their structure and functions and is currently tied to the regulatory status of wetlands. But assessing the degree of connectivity is difficult and new approaches to make these assessments. ARS researchers at Beltsville, MD research demonstrated the utility of Light Detection and Ranging (LiDAR) to more accurately map the local stream network and show connectivity of wetlands to the larger landscape. This capability will improve our ability to gauge the environmental services provided by wetlands that are often considered to be isolated and will lead to increased ability to protect wetlands that improve the environment.

6. ARS researchers at Beltsville, Maryland: Improved ability to predict wetland hydroperiod. The length of time that a wetland is saturated (a measure of hydroperiod) is an important determinant of ability of wetland ecosystems to store soil organic carbon but the ability to predict wetland hydroperiod is difficult. The use of Light Detection and Ranging (LiDAR) derived high resolution Digital Elevation Models (DEMs) permits derivation of topographic metrics that are highly predictive of wetland hydroperiod. This study found that combinations of indices of topographic wetness and local relief were highly prediction of wetland hydroperiod. The ability to extrapolate these measurements to the landscape and watershed scales holds promise for large scale estimates of carbon storage in wetlands. Wetland carbon storage is considered to be an important ecosystem service. Sexton, A., Shirmohammadi, A., Sadeghi, A.M., Montas, H.J. 2011. A stochastic method to characterize model uncertainty for a nutrient TMDL, Transactions of the ASABE. 54(5):2197-2207. Lang, M., McDonough, O., McCarty, G., Oesterling, R., Wilen, B. 2012. Enhanced detection of wetland-stream connectivity using LiDAR. Wetlands. 32:461-473. Lang, M., McCarty, G., Oesterling, R., Teo, I.Y. 2012. Topographic metrics for improved mapping of forested wetlands. Wetlands. 33:141-155.

7. ARS researchers at Oxford, Mississippi: Progress continues in assembling a comprehensive data set to describe Beasley Lake watershed, including soils, cropping patterns, cultural practices, topography, climate, water quality, and Light Detection and Ranging (LIDAR). These data are added to the STEWARDS (Sustaining the Earth’s Watersheds: Agricultural Research Data System) data base. Monitoring of lake water quality and fish populations and evaluation of runoff from Conservation Reserve Program and buffer areas continues. Collaborative efforts were maintained through routine site visits, email, and telephone communications with collaborators, and with participation at CEAP leaders meeting.

8. ARS researchers at El Reno, Oklahoma: Landscape predictors of stream phosphorus (P) concentrations. Agricultural land uses have been identified as one of the greatest contributors to impairment of water quality in the US, and in many regions high P concentration has been identified as the most limiting factor related to impaired water quality. Based on long term studies in the Fort Cobb Reservoir Experimental Watershed, a Conservation Effects Assessment Project Benchmark Watershed, ARS researchers at El Reno, OK; Watkinsville, GA; and College Station, TX, identified spatial patterns in P in streams associated with landscape metrics during wet and dry periods. Stream P concentrations were 3 to 5 times higher during wet periods than dry periods. Lateral metrics (topography, soil, geology, management) were better predictors than in-stream metrics for P concentrations in streams. During the wet period, metrics indicative of rapid surface and subsurface water movement were associated with higher P stream concentrations. The ability to identify portions of the landscape more vulnerable to P losses is an essential first step in developing better strategies for targeting conservation practices and sites within a watershed. Franklin, D.H., Steiner, J.L., Duke, S.E., Moriasi, D.N., Starks, P.J. 2013. Spatial considerations in wet and dry periods for phosphorus in streams of the Fort Cobb watershed, USA. Journal of the American Water Resources Association. DOI:10.111/jawr.12048. (Log # 260535)

9. ARS researchers at West Lafayette, Indiana: Throughout much of the upper Midwestern US, a landscape feature known as potholes or closed depressional areas is common. The soils in potholes are highly productive, but cannot be farmed without supplemental surface drainage. ARS researchers at West Lafayette, IN, identified the extent of potholes within a watershed can be directly correlated to the loads of nutrients in streams and ditches. These same ARS researchers worked collaboratively with NRCS to develop a practice, called a blind inlet, to decrease phosphorus loss from fields by about 78 percent and nitrogen loads by approximately 50 percent compared to the common practice in the region, known as a tile riser. ARS worked with NRCS to establish the practice into a conservation practice standard, and blind inlets can now be cost shared through the Environmental Quality Incentives Program (EQIP) in Indiana, and Ohio is currently in the process of adopting this conservation practice standard. A paper was published on this work from the St. Joseph River Watershed CEAP project in Soil Use and Management, the official journal of the British Society of Soil Science. The impact of this work has been to provide technology to NRCS that can directly lead to improved water quality. Smith, D.R., Livingston, S.J. 2013. Managing farmed closed depressional areas using blind inlets to minimize phosphorus and nitrogen losses. Soil Use and Management. 29(Suppl. 1):94-102. (Log # 267832)

10. ARS researchers at Tifton, Georgia: Conservation Effects Assessment Project: Herbicide transport in a coastal watershed depends on timing of application, enhanced degradation rates, and the presence of buffers. Agrichemical transport to coastal waters may have adverse ecological impacts. ARS researchers at Tifton, GA., used a combination of field studies and simulation modeling to understand atrazine fate and transport in a watershed adjacent to Puerto Rico’s Jobos Bay National Estuarine Research Reserve. Surface runoff due to tropical storms appeared to carry most of the atrazine that moved toward the estuary. Modeling studies showed that the majority of atrazine moved in dissolved form in surface runoff during a tropical storm and that under high rainfall and runoff conditions riparian buffers were less effective at intercepting the herbicide before it reached the estuary. Transport to the estuary was also limited by very rapid atrazine dissipation in the field soil and suggests that atrazine runoff potential is limited unless a tropical storm event occurs immediately following application.

11. ARS researchers at Temple, Texas: Methods for determination of optimal fertilizer application rates were developed and evaluated. Results from this research at the USDA-ARS Riesel Watershed and sites across Texas indicated increased profit potential and decreased input cost and production risk. In only 6% of the time was the traditional fertilizer rate the most profitable, compared to 51% for the unfertilized treatment and 43% for the enhanced soil test treatment. This does not indicate that fertilizer application should be avoided but that fertilizer rates should be carefully chosen considering all sources of plant available nutrients to ensure that fertilizer is applied at the optimal rate. This information is useful to agricultural producers, who are attempting to increase profitability and sustainability of their operations, and to land management agencies, who are hungry for science-based solutions to natural resources conservation problems. Harmel, R.D., Haney R.L. 2013. Initial field evaluation of the agro-economic effects of determining nitrogen fertilizer rates with a recently-developed soil test methodology. Open Journal of Soil Science 3(2):91-99.

12. ARS researchers at Temple, Texas: Fecal bacteria contamination of surface waters continues to be a critical water quality concern with serious human health implications, but relatively few land use specific data sets are available to guide management, restoration, policy, and regulatory decisions. In regions with substantial poultry production, litter application sites are often assumed to be major contributors to bacterial contamination, and grazing lands often receive a similar focus. Based on three years of water quality data collected from 13 watersheds in this study, litter application did not impact E. coli concentrations in runoff, which can at least partially be attributed to the late summer target application date. Litter was produced and removed from poultry houses during hot, dry conditions unfavorable for E. coli survival. Thus, late summer application may be a recommended practice to minimize E. coli runoff from litter application sites. Cultivated watersheds with and without litter application produced the lowest E. coli concentrations in runoff, presumably due to limited wildlife presence and livestock exclusion. In contrast, the ungrazed native prairie reference site produced relatively high E. coli concentrations in runoff, presumably due to increased fecal deposition from abundant wildlife. The high concentrations of E. coli from grazed lands emphasize the need for livestock producers to follow best management practice recommendations to minimize bacteria contribution; however, it is important to note that high E. coli concentrations were measured in runoff from well-managed grazing lands as well as ungrazed native prairie, which indicates the difficulty of managing bacterial contamination. Harmel, R.D., Wagner K.L., Martin E., Gentry T.J., Karthikeyan R., Dozier M., Coufal C. 2013. Impact of poultry litter application and land use on E. coli runoff from small agricultural watersheds. Biological Engineering Transactions. 6(1):3-16.

13. ARS researchers at Columbia, Missouri: Vegetative buffers reduce transport of Sulfamethazine. Veterinary antibiotics (VAs) can be introduced into the soil environment when animal manures are land applied , creating the potential for the development of antibiotic-resistant genes in soil microorganisms. Two studies were conducted in collaboration with researchers at the University of Missourito assess the mobility of the VA, sulfamethazine (SMZ), in soils collected from cropland, grass buffers, and tree-grass buffers. Soils collected from grass buffer or tree-grass buffers tended to have greater organic matter and lower pH than cropped soils, resulting in increased SMZ sorption. Because of its greater binding to the buffers soils, SMZ leaching through soil columns was also less for the soil collected from the tree-grass buffer compared to that of the cropland soil. These results showed that vegetative buffers create soil conditions that can enhance the binding of SMZ and impede its transport in surface runoff. This research will benefit land management, growers, and the public by providing evidence to support the use of vegetative buffers for mitigating VA transport from treated cropland; thus, decreasing the threat of spreading antibiotic resistant genes that could lead to difficulty in treating human pathogens with existing antibiotics. Chu, B., Goyne, K. W., Anderson, S. H., Lin, C. H., Lerch, R. N. 2013. Sulfamethazine sorption to soil: Vegetative management, pH, and dissolved organic matter effects. Journal of Environmental Quality. 42:794-805. Chu, B., Anderson, S. H., Goyne, K. W., Lin, C. H., Lerch, R. N. 2013. Sulfamethazine transport in agroforestry and cropland soils. Vadose Zone Journal. DOI:10.2136/vzj2012.0124.

14. ARS researchers at Columbia, Missouri: Agricultural Policy / Environmental eXtender (APEX) model parameterization and calibration. The APEX model has been developed to assess a wide variety of agricultural water resource, water quality, and other environmental problems over a complex area: landscape, whole farm, and watersheds. The model includes many input parameters whose values must be determined and adjusted to obtain a good match between model results and observed data. Scientists and researchers who want to use APEX need guidance about the steps of this process. USDA ARS scientists collaborated with University of Missouri scientists and others to highlight important parameters and provide guidance about the input parameters and how they can be adjusted to obtain results that match measured data. Several case studies are presented: a 35-ha field in north central Missouri, the 5720-ha Clear Creek watershed in central Texas, and several catchments at the Greenley research site in north Missouri. Together they provide examples of APEX applications to simulate streamflow, crop yields, and sediment, nutrient and atrazine yields. These results are important to ensure that APEX, a model used to estimate the environmental and productivity impacts of agricultural management practices, is correctly used. Wang, X., Williams, J.R., Gassman, P.W., Baffaut, C., Izaurralde, C., Jeong, J., Kiniry, J.R. 2012. EPIC and APEX: Model Use, Calibration, and Validation. Transactions of the ASABE 55(4):1447-1462. Senaviratne, A., Udawatta, R.P., Baffaut, C., Anderson, S.H. 2013. Agricultural Policy Environmental eXtender simulation of three adjacent row-crop watersheds in the claypan region. Journal of Environmental Quality. 42:726-736.

15. ARS researchers at Columbia, Missouri: Sediment organic carbon (C) distribution in small lakes and ponds. Small man-made impoundments including farm ponds, drinking water reservoirs, and recreational lakes ranging in size from 0.5 to 250 acres occupy over five million acres of the land surface in the United States. Organic carbon buried in the sediments of these impoundments is an important component of the global C cycle and its measurement is critical to understand how the buried C can help alleviate carbon dioxide levels in the atmosphere. Essentially no standard methods are available for sediment sampling and calculation of sediment C in small (<12 acres) lakes and ponds. ARS researchers, collaborating with University of Missouri researchers, developed an accurate method to calculate and quantify the organic C content in lake sediments. The sampling method also aids in determining the distribution of organic C within sediments and improves our understanding of small lake contributions to global C accumulation. Results of this study are important to accurately quantify that portion of the C cycle represented by sediments in numerous small lakes in a given region, thereby aiding in research planning and decision-making. Pittman, B., Jones, J.R., Millspaugh, J.J., Kremer, R.J., Downing, J.A. 2013. Sediment organic carbon distribution in 4 small northern Missouri impoundments: implications for sampling and carbon sequestration. Inland Waters: Journal of the International Society of Limnology. 3(1):39-46 DOI: 10.5268/IW-3.1.507.

Last Modified: 06/24/2017
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