Project : USDA ARS

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Research Project: Sustaining Agroecosystems and Water Resources in the Northeastern U.S.

Location: Pasture Systems & Watershed Management Research

2021 Annual Report

Objectives
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.

Approach
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.

Progress Report
Data from the wetlands lysimeter leaching studies have been summarized, and results are in the process of being interpreted. Preliminary results suggest that some forms of phosphorus, such as ortho-P, are not retained by wetland soils, while others, such as phytate, are almost fully retained within the top twelve inches of wetland soils. A paper documenting the results is planned. Manure priming study plots were planted in spring 2021, scheduled fertilizer applications were made, and soil samples have been submitted to the Cornell Soil Health Laboratory. Evaluation of corn yield data from 2018-2020 has not shown an advantage of the manure applications. Yield monitoring will continue this fall. A second manure application is planned for the spring of 2022. Field observations of urea generation revealed that microbial processes of organic matter decomposition generate urea under reducing conditions. These findings were published in the Journal of Environmental Quality. A second publication on microbial community dynamics associated with urea generation is being drafted by the recent Ph.D. graduate conducting postdoctoral work with ARS in Tifton, Georgia. Studies of nutrient movement through seeps in the landscape are complete. The results were published in Hydrological Processes in 2021. Findings indicated that the headwater stream under investigation was mainly disconnected from the underlying aquifer during baseflow and that riparian seeps supplied nearly all the water and nitrogen. A nitrate transit time study was published in Water Resources Research with collaborators from Johns Hopkins University, but the crux of the nitrate transit time work was put on hold until a postdoc could be hired to lead the work. A postdoc position for the nitrate transit time work was approved in FY20, and a search is underway to fill this position. Two papers were published from the ERI / tracer studies at University of Maryland Eastern Shore (UMES): one using ERI to document the flow paths and velocities of tracer transport in the vicinity of an open ditch, and a second one using hydrograph separation and concentration-discharge relations to understand the sources and pathways of dissolved phosphorus transport during storms. Results from this work are being used to inform the subsurface components of P Indices on the Delmarva Peninsula. In addition, these studies led to another five-year AFRI project that seeks to implement changes to P Indices and P management in flat, ditch-drained agroecosystems. The late fall manure application study is complete. A paper has been published reporting that manure injection combined with winter rye crop that was harvested for forage prior to silage corn planting increased overall forage production and nutrient recovery. Progress on the gypsum application study has been delayed due to the absence of the primary University of Maryland Eastern Shore (UMES) collaborator due to COVID restrictions and the departure of the UMES co-collaborator who accepted a faculty position at Morehead State University. We plan to resume collaboration on this study once COVID restrictions are lifted, and relocation activities are complete. Data from our work on removing nitrogen from the final effluent of the Manure Phosphorus Extraction (MAPHEX) System have been summarized, and results have been interpreted. A redesign of the system has been planned for further testing. Preliminary results suggest that 60% of total N can be removed from the final effluent of the MAPHEX System using a low-cost, low-tech N removal system. Both an ARS Invention Disclosure (possibly leading to a patent on the system) and a paper documenting the results are planned. A publication on the effectiveness of Conservation Reserve Enhancement Program (CREP) riparian buffers has been drafted and will be submitted by August 2021. Soil and Water Assessment Tool modeling buffers within four agricultural watersheds in Maryland and Pennsylvania estimated that CREP riparian forested buffers reduce nitrogen runoff from adjoining catchments by 17 to 56%, and phosphorus runoff by 4 to 20%. Similarly, grass buffers reduce nitrogen runoff by 16 to 49%, and phosphorus runoff by 4 to 18%. The study highlights the importance of implementing upslope conservation measures that protect the buffer from being undermined by gullies and ditches that route runoff water around the buffer. A paper was published providing qualitative comparisons of runoff forecasting tools, but the quantitative comparison studies and the Soil and Water Assessment Tool (SWAT) modeling study could not be completed due to the early departure of a postdoc who was expected to lead these efforts. A paper was published in the Journal of Environmental Quality that supports the recommendation of aluminum sulfate as a cost-effective remedial strategy for reducing elevated P in surface water used for cranberry production. Continuous monitoring at the WE-38 weir was maintained throughout the period of COVID restrictions. Plans have been made to add one additional instrument for testing in August 2021. A paper was published in Transactions of the American Society of Agricultural and Biological Engineers (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 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. Business As Usual and Aspirational crop rotation treatments for the LTAR Croplands Common Experiment have been maintained, and all scheduled sampling has been done at the plot and field scales. Manure was injected at the field scale site for the first time in Fall 2020 and again in Spring 2021.

Accomplishments
1. Winter cover crop management in diverse dairy forage production systems. Winter cover crops are known to prevent soil erosion, recover nutrients, and build soil health, but selecting the best options for cover crop management in diverse dairy forage production systems is complex. Collaborative research conducted by USDA researchers at University Park, Pennsylvania, and colleagues from the Pennsylvania State University in support of the Long-Term Agroecosystem Research (LTAR) network shows that planting winter rye cover crops immediately after corn silage harvest and delaying fall manure application until establishment increased nutrient recovery and improved cover crop yield. Maintaining the winter rye long enough in the spring to harvest silage (double cropping) adds to overall forage production without reducing the yield of the subsequent corn crop. The use of legume cover crops, which can be inter-seeded into summer crops, decreases the need for nitrogen fertilizers and increases the yield of subsequent crops in some years. These management options for dairy forage production systems allow producers to benefit from the soil erosion protection, nutrient recovery, and soil health benefits of winter cover crops.

U.S. DEPARTMENT OF AGRICULTURE

Pasture Systems & Watershed Management Research: University Park, PA