About

Brent Dalzell is an Adjunct Assistant Professor in the Department of Soil, Water, and Climate at the University of Minnesota. His research focuses on applied environmental geoscience, particularly the application of geochemical and modeling approaches to understand anthropogenic impacts on Earth resources. He studies soil biogeochemistry, including the sources, transformations, and sinks of organic carbon and nutrients in soils and connected aquatic ecosystems, utilizing techniques such as molecular and stable isotope biomarkers and GIS analyses of spatial datasets. His work aims to evaluate alternative management practices to improve environmental quality and address issues related to water quality, contaminant hydrology, and ecosystem modeling. Dalzell's contributions include investigating phosphorus transport in agricultural watersheds, the impacts of land management on soil organic carbon, and the role of vegetative and land use practices in influencing water and soil quality. His research supports efforts to enhance agricultural sustainability, reduce nutrient runoff, and improve ecosystem health through integrated assessment and innovative management strategies.

Research topics

• Computer Science
• Engineering
• Environmental science
• Water resource management
• Environmental resource management
• Ecology
• Geology

Selected publications

• Optimizing land management for nitrogen reduction: A bio-economic spatial model

  Journal of Environmental Management · 2025-03-01 · 1 citations

  articleOpen access

  Agricultural fertilizer contributes substantially to nitrogen pollution throughout the world, leading to many negative impacts including ecological dead zones. Alternative crop management practices, such as cover crops and perennial crops, can limit nitrogen pollution. To optimize land use changes to meet potential nitrate reduction scenarios, we develop a flexible geo-spatial economic framework, balancing nitrate reduction with reductions in farm profit. Cover crop and perennial crop patterns at the hydrologic response unit (HRU) level are simulated with a novel and more realistic management unit approach by combining Soil and Water Assessment Tool model outputs and an economic programming model. We apply our framework to a major Minnesota River Basin watershed, the Cottonwood River watershed, in the state of Minnesota, USA, finding that strategically located cover crops can be used to achieve significant nitrate effluent reduction, if perennial crops are optimally placed as a part of a collective effort. A large driver of nitrate pollution and reduction in profit is yearly variation, a proxy for precipitation volume-indicating that climate change may be particularly impactful in areas where climate change models predict significant changes in precipitation patterns.

  PublisherDOI

• Utility of near‐surface phenology in estimating productivity and evapotranspiration across diverse ecosystems

  Journal of Environmental Quality · 2025-06-02

  articleOpen access

  Abstract Agroecosystems, which include row crops, pasture, and grass and shrub grazing lands, are sensitive to changes in management, weather, and genetics. To better understand how these systems are responding to changes, we need to improve monitoring and modeling carbon and water dynamics. Vegetation Indices (VIs) are commonly used to estimate gross primary productivity (GPP) and evapotranspiration (ET), but these empirical relationships are often location and crop specific. There is a need to evaluate if VIs can be effective and, more general, predictors of ecosystem processes through time and across different agroecosystems. Near‐surface photographic (red‐green‐blue) images from PhenoCam can be used to calculate the VI green chromatic coordinate (G CC ) and offer a pathway to improve understanding of field‐scale relationships between VIs and GPP and ET. We synthesized observations spanning 76 site‐years across 15 agroecosystem sites with PhenoCam G CC and GPP or ET estimates from eddy covariance (EC) to quantify interannual variability (IAV) in the relationship between GPP and ET and G CC across. We uncovered a high degree of variability in the strength and slopes of the G CC ∼ GPP and ET relationships ( R 2 = 0.1 ‐ 0.9) within and across production systems. Overall, G CC is a better predictor of GPP than ET ( R 2 = 0.64 and 0.54, respectively), performing best in croplands ( R 2 = 0.91). Shrub‐dominated systems exhibit the lowest predictive power of G CC for GPP and ET but have less IAV in slope. We propose that PhenoCam estimates of G CC could provide an alternative approach for predictions of ecosystem processes.

  PublisherOA PDFDOI

• Combining soil conservation with phosphorus drawdown can confront legacy phosphorus accumulation and transfer

  Journal of Soil and Water Conservation · 2025-05-04 · 3 citations

  articleOpen access

  Legacy phosphorus (P) in agricultural soils (i.e., P that derives from historical human activities) can resist conventional nutrient management strategies to improve water quality (e.g., placement, rate, source, and timing of application). Further, soil conservation practices such as reduced tillage, while potentially beneficial for improving soil health and minimizing erosion, can promote dissolved P loss. Comprehensive legacy P management requires targeted mitigation strategies that consider the sources and processes involved in P mobilization and transport. We modeled trade-offs and interactions of nutrient management and soil conservation strategies in legacy P mitigation efforts at three key sites in the northern United States where legacy P contributions to water quality are a concern. The Annual Phosphorus Loss Estimator (APLE) model was used to simulate generalized management scenarios at each site: current site-specific practices, conventional conservation practices (no-till and manure injection), and P drawdown (curtailing fertilizer P additions and extracting P from soils via crop uptake and harvest). Modeled results highlight that the effects of legacy P are not always obvious; even at sites near the range of agronomic optimum, losses of legacy P in runoff can be significant. Phosphorus drawdown via crop uptake and removal offers the potential to deplete legacy P stores but requires dedication and time. In model simulations, no-till reduced total P losses due to reductions in sediment transport. Coupling drawdown strategies with appropriate conservation management to avoid inadvertent P losses can reduce both dissolved and particulate P losses. Focusing on either soil conservation or soil P drawdown alone is insufficient to meet water quality goals. Phosphorus drawdown strategies must be accompanied by practices supporting soil conservation to ensure that legacy P management benefits water quality in the short and long term.

  PublisherDOI

• Quantifying microplastics in environmental waters: Mass concentrations are superior to abundance

  Agricultural & Environmental Letters · 2025-10-07

  articleOpen access

  Abstract Microplastics are contaminants of global concern that are primarily studied in marine and urban environments. Understanding of microplastics in drained agricultural watersheds is lacking. We aimed to evaluate microplastics in ditch and tile drainage water through periodic sampling. Water samples were filtered to capture particulates that were digested to remove organics, then stained and evaluated using fluorescence microscopy and image analysis. Further, we compared and contrasted microplastic abundance, the current reporting standard, with microplastic mass concentration, often unreported, to determine the most accurate assessment. Open‐ditch drainage had greater microplastic contamination than drainpipe outlets. Agricultural drainage contained 2–6 orders of magnitude less mass concentrations of microplastics than sampled urban surface waters and laundry graywater. However, when evaluated by abundance, the difference was not apparent. These findings improve our understanding of microplastics in agricultural watersheds and demonstrate the importance of evaluating microplastic contamination based on mass concentrations for accurate assessments. Core Ideas Mass concentration (ng/L) is a better predictor of microplastic contamination than abundance (counts/L). Agricultural drainage water had lower microplastic mass concentrations than surface water or laundry graywater. Open‐ditch drainage had greater microplastic contamination than drainpipe outlets. Mass of microplastic pieces from smallest to largest: drainage water < river water < lake water = laundry water.

  PublisherDOI

• Integrated Assessment of Cost-Effective Water Quality Improvements in the Minnesota River Basin: Combining Stated Preferences and Simulation-Optimization Approaches

  Environmental Management · 2025-05-10 · 3 citations

  article
  PublisherDOI

• Using Spatially Rich Data Sets to Assess the Influence of Channel Characteristics on Biogeochemical Behavior in Agricultural Watersheds

  Water Resources Research · 2025-02-01

  articleOpen access

  Abstract Many agricultural landscapes have undergone significant modifications to drain farmland and improve crop productivity. Subsurface field drainage, ditching and channelization of streams limit opportunities for biogeochemical processing of carbon and nutrients within the channel network. In this study, we used spatially rich water quality data collected from two contrasting regions of an agricultural watershed in south‐central Minnesota, USA to assess how watershed features, such as channelization, tile drainage, and presence of lakes or wetlands, influence biogeochemical processing of nitrate (NO 3 − ) and dissolved organic carbon (DOC). In the channelized upstream region, land use is predominantly agricultural (>92%) with subsurface tile drainage commonly discharging directly to the stream channel. Further downstream, the channel is more natural with increasing lakes and wetlands, including riparian wetlands. We used the concept of reach leverage to interpret biogeochemical behavior (i.e., source vs. sink) in each region of the watershed. Results indicate variability in biogeochemical behavior between the distinct watershed regions, suggesting that channel characteristics and the presence of lentic waters play a role in regulating biogeochemical processing. The upstream, channelized region acts primarily as a conservative transporter or small source of both NO 3 − and DOC across sampling dates. In contrast, the lentic‐influenced region exhibited shifts between source and sink behavior over time, especially for NO 3 − , influenced by factors such as hydrologic connectivity and discharge. These findings highlight the value of collecting spatially resolved data to enhance our understanding of biogeochemical processing which may be useful to inform effective management and conservation strategies.

  PublisherOA PDFDOI

• The LTAR Cropland Common Experiment at Upper Mississippi River Basin–Ames

  Journal of Environmental Quality · 2024-10-27 · 2 citations

  articleOpen access

  Agricultural systems evolve from the interactions of climate, crops, soils, management practices (e.g., tillage, cover crops, nutrient management), and economic risks and rewards. Alternatives to the corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] (C-S) cropping systems that dominate in the US Midwest may provide more sustainable use of resources, reduce the documented environmental impacts of current C-S systems, and improve production efficiency and ecosystem services. Innovative management practices are needed to offer producers options to increase farm resilience to variable weather conditions and offset negative environmental impacts. In response to this need, the Upper Mississippi River Basin Long-Term Agroecosystem Research network site at Ames, IA, established a cropland experiment in 2016 to investigate an alternative crop management system that includes reduced tillage, cover crops, and right source, right rate, right time, and right place (4R) nitrogen (N) management. The experimental site is located on the Iowa State University Kelley Research Farm in Boone County, IA. Crop, soil, air, and tile drainage water measurements are made throughout the year using published methods for each agronomic and environmental metric. Our goal is to provide quantitative information to farmers, consultants, agribusiness partners, and state and federal agencies to help guide decisions on the effective use of alternative management practices. Future changes in experimental treatments will adopt a knowledge co-production approach whereby researchers and stakeholders will work collaboratively to identify problems, implement research protocols, and interpret results.

  PublisherOA PDFDOI

• The LTAR Common Experiment: Facilitating improved agricultural sustainability through coordinated cross‐site research

  Journal of Environmental Quality · 2024-10-15 · 16 citations

  reviewOpen access

  Long-term research is essential for guiding the development of agroecosystems to meet escalating production demands in a manner that is environmentally sound and socially acceptable. Research must integrate biophysical and socioeconomic factors to provide geographically scalable knowledge that involves stakeholders across the research-education-extension-policy spectrum. In response to this need, the Long-Term Agroecosystem Research (LTAR) network developed a "Common Experiment," which seeks to develop and disseminate multi-region, science-based information to enable implementation of visionary agricultural innovations while simultaneously promoting food security, well-being, environmental quality, and climate adaptation and mitigation. The core design of the Common Experiment contrasts prevailing and alternative/aspirational production systems, with the latter including novel innovations hypothesized to advance sustainable intensification in locally appropriate ways. Treatments in the Common Experiment represent a diversity of production systems under cropland, grazing land, and integrated crop/grazing land management. Where possible, treatments are evaluated at multiple spatial scales (e.g., from plot to enterprise) and are designed to evolve over the course of the experiment with stakeholder input. A common assessment framework guides data collection for the experiment and is complemented by metric-specific protocols and an emerging data management infrastructure. Currently, there are large differences among sites in the application of the experimental framework and degree of stakeholder engagement; differences largely grounded in pragmatic issues related to land access, site expertise, and resource availability. The full potential of the LTAR Common Experiment may be realized with strategic investments in network capacity.

  PublisherOA PDFDOI

• Optimizing Land Management for Nitrogen Reduction: A Bio-Economic Spatial Model

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access
  PublisherDOI

• Phosphorus lability across diverse agricultural contexts with legacy sources

  Journal of Environmental Quality · 2024-09-29 · 6 citations

  articleOpen access

  Abstract The buffering of phosphorus (P) in the landscape delays management outcomes for water quality. If stored in labile form (readily exchangeable and bioavailable), P may readily pollute waters. We studied labile P and its intensity for >600 soils and sediments across seven study locations in the United States. Stocks of labile P were large enough to sustain high P losses for decades, indicating the transport‐limited regime typical of legacy P. Sediments were commonly more P‐sorptive than nearby soils. Soils in the top 5 cm had 1.3–3.0 times more labile P than soils at 5–15 cm. Stratification in soil test P and total P was, however, less consistent. As P exchange via sorption processes follows the difference in intensities between soil/sediment surface and solution, we built a model for the equilibrium phosphate concentration at net zero sorption (EPC 0 ) as a function of labile P (quantity) and buffer capacity. Despite widely varying properties across sites, the model generalized well for all soils and sediments: EPC 0 increased sharply with more labile P and to greater degree when buffer capacity was low or sorption sites were likely more saturated. This quantity–intensity–capacity relationship is central to the P transport models we rely on today. Our data inform the improvement of such P models, which will be necessary to predict the impacts of legacy P. Further, this work reaffirms the position of labile P as a key focus for environmental P management—a view Dr. Sharpley developed in the 1980s with fewer data and resources.

  PublisherOA PDFDOI

Frequent coauthors

• D. J. Mulla

  University of Minnesota System

  25 shared

• Christine L. Dolph

  University of Minnesota

  18 shared

• Se Jong Cho

  18 shared

• Jacques C. Finlay

  Saint Anthony College of Nursing

  17 shared

• Efi Foufoula‐Georgiou

  Irvine University

  17 shared

• Amy T. Hansen

  University of Kansas

  15 shared

• Prasanna H. Gowda

  14 shared

• Gary W. Feyereisen

  12 shared

Labs

• Soil and Water Management ResearchPI

Education

• Ph.D., Earth and Atmospheric Sciences

  Purdue University

  2004

• M.S., Water Resources Science

  University of Minnesota

  2000

• B.S., Biology

  University of Wisconsin–La Crosse

  1997

• A.A.

  Anoka-Ramsey Community College - Coon Rapids Campus

  1995