Location: Pasture Systems & Watershed Management Research2022 Annual Report
Objective 1: Describe and quantify processes controlling agriculturally related environmental contaminants (C, N, and P) to reduce inputs to receiving waters (C2, PS 2.1). Subobjective 1.1: Characterize chemical, physical and biological controls of contaminant mobility and transport in water at pedon, field, landscape and watershed scales. Subobjective 1.2: Characterize the spatial nature and temporal dynamics of transport pathways connecting sources of key agricultural contaminants with surface and ground waters. Objective 2: Adapt and develop management practices that farmers can use to reduce the environmental impacts of agriculturally derived contaminants on receiving waters (C1: PS 1.5; C2: PS 2.4; C3: PS 3.1 and 3.2; C4: PS 4.2). Subobjective 2.1: Identify, evaluate, and develop fertilizer, manure, tillage, irrigation and drainage management practices that improve production use efficiency and minimize off site transfers to surface and ground waters. Subobjective 2.2: Develop new technologies, management practices and decision support tools that recognize the spatial variability of the landscape and focus mitigating efforts on critical source areas or critical pathways. Objective 3: Conduct plot, field and watershed studies to understand processes that link cranberry production to water resources and develop appropriate conservation practices to protect water quality (C1: PS 1.5; C2: PS 2.4; C3: PS 3.1 and 3.2; C4: PS 4.2; NP305 C1: PS 1B). Subobjective 3.1: Characterize temporal and spatial patterns of N and P discharge from cranberry farms. Subobjective 3.2: Develop new technologies and management practices that improve water quality and enhance water use efficiency on cranberry farms. Objective 4: As part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the mid-Atlantic Region, use the Upper Chesapeake Bay Experimental Watersheds LTAR site to improve the observational capabilities and data accessibility of the LTAR network and support research to sustain or enhance agricultural production and environmental quality in agroecosystems characteristic of the region. Research and data collection are planned and implemented based on the LTAR site application and in accordance with the responsibilities outlined in the LTAR Shared Research Strategy, a living document that serves as a roadmap for LTAR implementation. Participation in the LTAR network includes research and data management in support of the ARS GRACEnet and/or Livestock GRACEnet projects. (C4: PS 4.1; NP 212 C1: PS 1B; NP 216 C5: PS 5A) Subobjective 4.1: Support the LTAR common observatory by monitoring and modeling long term changes affecting water resources and contributing to LTAR’s common database. Subobjective 4.2: Support LTAR’s common experiment and Dairy Agro-ecological Working Group (DAWG) water research objectives by comparing water resource impacts of a long term conventional dairy forage rotation (corn, soybean, and alfalfa) with a diversified dairy forage rotation that, in addition, includes winter cover crops, perennial grasses for bioenergy feedstock, and grazed pasture.
Research will span the Chesapeake Bay and Buzzards Bay watersheds, relying upon core sites in the Atlantic Coastal Plain (Manokin watershed, MD; Buzzards Bay watershed, MA), Appalachian Piedmont (Conewago watershed, PA), Appalachian Valley and Ridge (Mahantango Creek watershed, PA and Spring Creek watershed, PA), and Allegheny Plateau (Anderson Creek watershed, PA). Research emphases will vary across these locations, reflecting issues that are of current management or scientific relevance as well as constraints imposed by available resources. Our primary distinction is between the Atlantic Coastal Plain (in the Chesapeake and Buzzards Bay watersheds) and the upland physiographic areas of the Chesapeake Bay watershed, as hydrologic flow paths are dramatically different in these landscapes (subsurface flow is the dominant hydrologic pathway in the Atlantic Coastal Plain, whereas overland and shallow lateral flows are the major pathways in the upland provinces). We have landowner contacts and research collaborators at all major (core) sites and have a research infrastructure that enables routine measurement and chemical sampling of surface runoff, subsurface flow, and stream flow. When necessary, we move infrastructure from one location to another to provide a greater intensity of observations. We combine field observations with laboratory experiments in which greater control may be obtained over indirect variables. Our process-oriented research (Objective 1) involves observational and experimental studies, using parametric and nonparametric statistics to quantify temporal and spatial trends or to determine differences between management/land use, landscape units, and watershed components. Our applied research (Objectives 2-4) includes experimental studies, remote sensing and modeling. Experimentation involves a high degree of replication due to the inherent variability in processes impacting water quality. We have strong in-house statistical capability and, when necessary, consult with outside statisticians to ensure confidence in our findings.
A manuscript summarizing nine wetlands with different histories of alteration has been submitted for publication. Data from the wetlands lysimeter leaching studies have been summarized, and results have been interpreted. Results suggest that some forms of phosphorus, such as ortho-P, are not retained by wetland soils. Other forms, such as phytate, did not leach from the lysimeters, suggesting that they are almost fully retained within the top twelve inches of wetland soils. However, sorbed phytate in soil could not be extracted to prove that it was retained. The partial results are not sufficient for publication. A paper on seasonal and temporal factors leading to urea-nitrogen accumulation in surface waters of agricultural drainage ditches was published in the Journal of Environmental Quality. Results showed that terrestrial sources of urea are related to organic matter decomposition in anaerobic environments, such as ditch bottoms and wetlands, during warm seasons when microbial processes are active. A second manuscript describing microbial population dynamics related to urea accumulation is in draft by the UMES graduate student who is now an ARS Research Associate at Tifton, Georgia. Publications from nitrate transit time study remain in development. The age-dating wells, which were supposed to inform these analyses, were just installed in spring of 2022 after years of delays. Collaborative work with colleagues at Johns Hopkins (Wilusz et al., 2020) provided insight into transit times in FD-36, but we have yet to pull all this information together with the age-dating wells and our long-term isotope archive in WE-38. A paper was published in Transactions of the ASABE detailing the hydrological changes anticipated with future climate change. The study focused on Spring Creek, an Upper Chesapeake Long-Term Agroecosystem Research (LTAR) basin that is underlain by karst. Results showed that incorporating the effects of carbon dioxide in Soil and Water Assessment Tool (SWAT) significantly reduced plant transpiration and increased runoff relative to two SWAT models that discounted the effects of carbon dioxide. The land-use portion of the SWAT modeling study could not be completed as planned, as the postdoc left ARS for a faculty position before that part of the study commenced. As this project terminates, our work under objective one led to a better understanding of wetland processes that govern P dynamics and urea generation in uplands. Our characterization of nitrate movement in groundwater provides a better estimate of the lag time between implementing conservation practices to reduce nitrate losses and improvements in water quality. Under objective two, we demonstrated that P losses in runoff can be reduced by applying gypsum to soils as a source of soluble calcium that reduces the solubility of P, and we developed a filtration process for removing P from liquid dairy and swine manure. Our work on cranberries under objective three provided a better understanding of nutrient profiles (N and P) in bog soils and the conditions under which nutrients are lost in drainage water. We also developed a conservation practice for reducing P loss in drainage water by adding alum to irrigation holding ponds. Our research contribution to the LTAR network under objective four provided better understanding of watershed effects of implementing aspirational practices compared to business-as-usual practices.
Slaton, N.A., Lyons, S.E., Osmon, D.L., Brouder, S.M., Culman, S., Gatiboni, L.C., Hoben, J., Kleinman, P.J., Mcgrath, J.M., Miller, R., Pearce, A., Shober, A., Spargo, J., Volenec, J.J. 2021. Minimum dataset and metadata guidelines for soil-test correlation and calibration research. Soil Science Society of America Journal. 86:19-33. http://doi.org/10.1002/saj2.20338.
Sebring, R.L., Duiker, S.W., Berghage, R.D., Regan, J.M., Lambert, J.D., Bryant, R.B. 2022. Gluconacetobacter diazotrophicus inoculation of two lettuce cultivars affects leaf and root growth under hydroponic conditions. Horticulturae. 12(3):1585. https://doi.org/10.3390/app12031585.