Project : USDA ARS

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Research Project: Managing Water Resources to Foster the Sustainable Intensification of Agroecosystems in the Northeastern U.S.

Location: Pasture Systems & Watershed Management Research

2025 Annual Report

Objectives
Objective 1. Describe and quantify sources and transport processes that transfer agriculturally derived environmental contaminants to receiving waters. Objective 2. Assess the effectiveness of newly developed and existing conservation practices that reduce the risk of agricultural contaminant losses that negatively affect water quality. Subobjective 2.1. Identify, develop, and evaluate manure, fertilizer, tillage, irrigation, drainage, and nutrient management practices that improve production use efficiency and minimize off-site transfers. Subobjective 2.2. Develop new technologies and management practices that improve and protect soil health. Sub-Objective 2.3. Modernizing soil testing to optimize agricultural and environmental priorities and achieve precision management. Objective 3: Develop management strategies and practices that conserve water resources and enhance agroecosystem services of wetlands cultivated for cranberry production. Subobjective 3.1. Characterize soil carbon dynamics and temporal and spatial patterns of nutrient discharge from cranberry farms. Subobjective 3.2. Develop new technologies and management practices that enhance water use efficiency and improve water quality on cranberry farms. Objective 4 . In support of LTAR network goals, design sustainable agricultural systems that balance production, environmental, and rural prosperity objectives under changing agricultural and climatic conditions in the northeastern U.S.

Approach
Research spans 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), and Appalachian Ridge and Valley (Mahantango Creek watershed, PA and Spruce Creek watershed, PA). The scope of our research encompasses entire agroecosystems and the supporting industrial complex. The water quality emphasis is primarily on controlling nutrient (N and P) loss to the environment. Increasingly, our research addresses carbon as related to climate change mitigation and adaptation. In the Upper Chesapeake Bay, we focus primarily on dairy production, the most common production system in the watershed. Similarly, our Congressionally mandated work on cranberry production (Objective 3) focuses on cranberry production enterprises and related externalities in the Buzzard Bay watershed. The private enterprise is at the center of our work because the individual producer is a key decision maker. Research activities represent targets of opportunity as identified by scientists and/or stakeholders or are in response to external funding opportunities that have been prioritized by funding agencies and that leverage internal resources and university partnerships. As a member of the LTAR network, outcomes have relevance to other agroecosystems and outcomes from research by other members of the network have relevance to our region. Linkages between our research activities and those of the other 19 LTAR research programs are too numerous to describe in detail, but collectively, outcomes from research across the network have greater potential for producing significant new, actionable knowledge for the dairy and cranberry industries than from our work alone. 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 core sites and a research infrastructure that enables measurement and chemical sampling of surface runoff, subsurface flow, and stream flow. We combine field observations with laboratory experiments that allow for greater control over indirect variables. Our basic research (Objective 1) involves observational and experimental studies, using parametric and nonparametric statistics as well as numerical models to quantify temporal and spatial dynamics or determine differences between management/land use, landscape units, and watershed components. Our applied research (Objectives 2-4) includes experimental studies, remote sensing, and modeling.

Progress Report
Scientists assigned to the Water Quality project continue to make progress on research outlined in the five-year project plan. Objective 1 of the project plan includes four objectives that aim to describe the processes governing pollutant fate and transport in agricultural watersheds. In 2024, enduring dry spells in the spring and fall months prevented us from sampling the age dating wells as planned. The dry spell in the fall of 2024 was particularly long lasting (the watershed saw nearly 30 days without measurable rain), and the resulting drought (rated severe by the U.S. Drought Monitor) persisted well into the spring of 2025. Given that summer is not an ideal time to sample groundwater wells (due to evapotranspiration effects and highly variable recharge conditions), we now plan to sample in the fall of 2025. The high-frequency nitrate sensing project (1.A.2) remains on course. We analyzed nitrate concentration-discharge relationships at the Little Conewago Creek gauging station as planned. Moreover, a paper describing nitrate concentration-discharge relationships in WE38 and one of its headwater subbasins is currently in revision with Water Resources Research. The project using near-surface geophysics to examine critical source areas of subsurface phosphorus loss (1.A.3) is also on track. Members of the team presented findings from the geophysics research to stakeholders at the Mid-Atlantic Crop School in fall of 2024, and these presentations were well-received by the attendees, which included farmers and producers across the Mid-Atlantic region. In addition, a paper on the plot-scale experiments with time-lapse electrical sensing and salt tracers was recently published in the Journal of Hydrology, and two additional papers are planned. Objective 2 of the project plan focuses on applied studies that seek to assess the water quality benefits of new and existing conservation practices. As detailed in the FY24 progress report, we were unable to advance the three projects (2.A.1, 2.A.2, and 2.A.3) under subobjective 2.1 that focus on the MAnure PHosphorus EXtraction (MAPHEX) system for removing phosphorus from liquid dairy manures. However, we completed three years of field studies to determine how corn yield responds to Lysine fertilization (2.A.4). The results of this work, which were published in Agronomy Journal, suggested no major differences in corn yield using lysine or urea ammonium nitrate as fertilizers. Finally, we continue to collaborate with the National Weather Service’s Middle Atlantic River Forecast Center on the runoff forecasting project in Mahantango Creek (2.A.5). Preliminary results from an assessment of ensemble forecast skill in 2018 (one of the wettest years on record) hold promise for probabilistic runoff forecasting in the Mahantango Creek watershed. We are expanding our hindcasting window to the past ten years, and we plan to have the analyses completed by the end of the 2025 calendar year. Subobjective 2.2 includes two studies that examine the benefits of different technologies and management practices on soil health. In the first study, low-yielding croplands are being amended with manure (aka manure priming) in order to track changes in soil health and crop yields (2.B.1). The study is in year three, and all activities remain on schedule, with a peer-reviewed publication expected in 2026. The study is part of a multi- location initiative that is supported by ARS’s Dairy Agroecosystems Workgroup (DAWG). The second study under this subobjective explores the utility of periodic tillage to redistribute phosphorus in agricultural soils with phosphorus stratification (2.B.2). Unfortunately, we face continued difficulties in finding four to six farms with cropped fields that meet the study’s two main criteria: (1) more than 10 years of no-till management and (2)periodic surface applications of manure. Objective 3 of the project plan centers on the sustainability of cranberry agriculture in the northeastern U.S. A key facet of the cranberry research program is to develop and test management practices that protect water resources and enhance ecosystem services. Subobjective 3.1 features two projects. The first project seeks to quantify carbon sequestration in active, restored, and retired cranberry farms (3.A.1). The second project aims to measure and model nitrogen delivery to the Buzzards Bay estuary (3.A.2). Over the past year, discharge rating curves and nitrogen concentrations were determined for the seven study rivers. The team is currently working with an undergraduate student at the University of Virginia to quantify seasonal and annual nitrogen fluxes from the seven study rivers to the estuary. Subobjective 3.2 involves developing and testing new technologies and practices for cranberry management. The first project under this subobjective proposes to evaluate the extent to which multi-zone variable rate irrigation improves water efficiency in cranberry production (3.B.1). The project was delayed somewhat due to changes in the research plan that were implemented last year to better capture soil moisture variability across the different irrigation zones. Further delays occurred while IT reviewed the automated irrigation system that was purchased for the research. Despite these setbacks, the project is mostly on schedule, with field work and data collection wrapping up in the 2025 growing season. The second study initially proposed to evaluate aluminum sulfate (alum) as a phosphorus sorbing agent in cranberry ponds (3.B.2), but this project was shelved in favor of a new project that better reflected the interests of the Cape Cod Cranberry Growers Association. In short, the new project proposes to assess the potential for tailwater recovery systems to enhance water quality in cranberry agriculture. In spring 2025, the project team completed a detailed survey of 28 tail water recovery ponds in southeastern Massachusetts. Later this year, the team will select a subset of these sites for more detailed study. Objective 4 advances research that is part of the Long-Term Agroecosystem Research (LTAR) Croplands Common Experiment. We continue to work closely with university collaborators at Penn State to implement the LTAR common experiment at University Park (4.A.1), including carrying out scheduled field operations for crop rotations and conducting soil, plant, and water sampling as specified in the project plan.

Accomplishments
1. Electrical sensing with tracers reveals subsurface pathways involved in dissolved phosphorus transport.. Describing the hydrologic pathways that connect farm fields with surface waters is essential to controlling phosphorus losses from agriculture. Such knowledge is particularly important in flat landscapes with open ditch drainage, where the bulk of phosphorus transport often occurs in subsurface groundwater flow. In this study, ARS researchers at University Park, Pennsylvania, partnering with colleagues from University of Delaware, Rutgers University, University of Maryland Eastern Shore, and Morehead State University, injected a conductive salt tracer into shallow groundwater and then simulated a large rainstorm with a purpose-built sprinkling system. During the simulated rainstorm, the team used advanced electrical sensing methods to track the movement of the tracer over time. Results showed that groundwater preferred to move rapidly through a thin layer of coarse gravels embedded within the fine sandy aquifer. The speed of tracer transport in the preferential groundwater flow path was fast, approaching 50 feet per day. In contrast, transport through the surrounding fine sands was much slower, covering the same distance in about a year. Findings show that subsurface transfers of water and associated nutrients like phosphorus can be rapid, even in flat agricultural fields. This type of information is valuable, as it enables producers to direct their phosphorus applications to areas of fields that are less susceptible to subsurface transport. By increasing the precision of phosphorus applications, producers can use their phosphorus reserves more efficiently so that crop yields are enhanced and water quality is protected.

2. Quantifying the effects of tile drainage on nutrient losses from cranberry production.. Cranberry production is the largest cash-crop in southeastern Massachusetts, but its connection to water resources may lead to impaired water quality. In this study, ARS scientists from University Park, Pennsylvania, teamed up with researchers from the University of Massachusetts-Amherst to evaluate the effects of tile drainage, a relatively new but popular form of artificial drainage in southeastern Massachusetts, on nutrient losses from cranberry agriculture. Tile drainage had a greater impact on soil losses of phosphorus (P) than nitrogen (N), with two times higher P loads in tile drainage than surface water. We observed retention of P in open ditches, which may mediate the flow of P from tile drainage to surface water in cranberry farms and other agroecosystems. Our findings also highlighted the impact of extreme precipitation events on nutrient losses from these systems, particularly when they coincide with fertilizer application events. These results suggest that reducing nutrient losses from tile-drained systems can be achieved by periodic removals of ditch sediments and greater flexibility in the timing of fertilizer application events to avoid major rainstorms.

3. Historical changes in cranberry phenology impact water management.. Changes in cranberry phenology – which describes the timing of key life cycle events like bud break, flowering, and fruit development – affect almost every cranberry grower in Massachusetts and Wisconsin, where frost protection directly depends on the phenological stage of the plant. Cranberries rank first in cash crops in Massachusetts, where a quarter of the nation’s cranberries are produced. In Massachusetts, rising air temperatures have affected the phenology of cranberries and by extension, the management of spring frost protection. To better understand and address this problem, a team of ARS scientists in University Park, Pennsylvania, and their colleagues from the University of Massachusetts-Amherst analyzed field observations of the phenological stage of cranberries from 1958 to 2022. The research team found that rising air temperatures have caused bud development to occur roughly 20 days earlier now than in the 1950s. Such changes will require new frost protection models that not only account for phenological variations in cranberries across the growing region, but also capture changes in cranberry phenology over time.

4. Long-term rainfall observations show that subhourly rainfall events in spring are growing larger and happening more often.. A growing body of research reports that extreme rainfall is intensifying around the world. Most evidence points to the intensification of daily rainfall extremes. However, subhourly rainfall extremes – those that occur in less than an hour – appear to be increasing faster than hourly and daily rainfall extremes. In this study, ARS researchers at University Park, Pennsylvania, used 55 years of 5- minute rainfall measurements from the Mahantango Creek experimental watershed to determine how 15- minute (subhourly), hourly, and daily rainfall extremes had changed over time. Findings showed that the magnitude and frequency of 15-minute rainfall extremes increased faster than hourly and daily extremes in the spring season. Notably, the largest 15-minute rainfalls in spring were 0.2 inches larger and occurred 1.7 times more often in 2022 than in 1968. Added evidence suggested that warming temperatures in the spring had enhanced the environment for thunderstorm development, which could partly explain the faster rise in subhourly rainfalls relative to those of longer durations. Findings from this study are relevant to farming interests in the Upper Chesapeake Bay region, as spring is an important season for field work, planting, and fertilization, and farmers often plan these activities around expected rainfall patterns. As such, findings from the study will help farmers cope with increasingly variable weather extremes in the spring.

U.S. DEPARTMENT OF AGRICULTURE

Pasture Systems & Watershed Management Research: University Park, PA