Tag: p-index

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Modeling Phosphorus Runoff in the Chesapeake Bay Region to Test the Phosphorus Index

Purpose

To assess and advance site assessment for P based management. This presentation is part of a symposium addressing the P Index.

What did we do?

The revision of USDA-NRCS’s standard for nutrient management coincided with significant assessment of the performance of Phosphorus (P) Indices in the six states that are tied to the Chesapeake Bay watershed. The 64,000 square mile watershed is the focus of unprecedented activity around nutrient management as a result of a 2011 Total Maximum Daily Load for P, nitrogen (N), and sediment under the Clean Water Act. In addition, the state of Maryland had required updates to it’s original P Index, resulting in broad scrutiny by various interest groups. Within this setting, USDA-NRCS funded a multi-state project to help advance the testing and harmonization of P-based management in the Chesapeake region.

States in the Chesapeake Bay region have had a long history of collaboration over P management. As a result, participants in the project decided to employ a unique approach to evaluating site assessment and P-based management on the basis of physiographic groupings. Expert panels were established for each of the major physiographic provinces in the region: (1) the Allegheny Plateau (NY, PA and WV); (2) the Appalachian Valley and Ridge (PA, MD, VA, WV) and the Appalachian Piedmont (PA, MD, VA); (3) and the Atlantic Coastal Plain (DE, MD, VA). Panels were comprised with representatives from the nutrient management planning community, the conservation community, the action agency community (state and federal), the farming community and researchers.

At the beginning of the project, each physiographic panel was charged with helping to identify the primary P management concerns for a province and the range of conditions that are most appropriate for site assessment. As the project evolves, panels will be expected to provide feedback on results, look for consistencies and differences between state approaches to site assessment, and, for states working to modify they site assessment approaches, offer input on suitable options.

What have we learned?

Modeling P runoff plays a fundamental role in the Chesapeake project. For each physiographic region, watersheds were identified where the SWAT model and the local P Index would be run to compare results. This objective has proven challenging to the SWAT model, as it requires a common scale of spatial inference with the P Index, i.e., the field. At the start of the project, the performance of SWAT was evaluated with regard to its representation of hydrologic and P cycling processes. It was determined that a version of SWAT that better represents variable source area hydrology, TOPO-SWAT, is best suited to the uplands of the Chesapeake Bay region. In addition, it was determined that the original P routines in SWAT are insensitive to the key nutrient management factors considered by the P Index (rate, timing, method and form of P application). Therefore, a new set of P routines was developed to correct the problem.

To-date, SWAT has been applied to watersheds in all of the physiographic regions of the Chesapeake Bay watershed: Factory Brook (NY) and Dressler Run (PA) in the Allegheny Plateau; Spring Creek (PA), Mahantango Creek (PA), Conewago Creek (PA), Upper Potomac (VA) in the Appalachian Mountains (Valley and Ridge as well as Piedmont). On the Atlantic Coastal Plain, where subsurface P losses to artificial drainage dominate, existing models were deemed inadequate. Therefore, an empirical approach to describing P transfers has been used that includes the application of geophysical imagining techniques to describe the flow paths connecting fields with drainage ditches.

Future Plans

Next steps of the project are to begin comparing P Index output with SWAT output for select field conditions under an array of management scenarios. At that point it is expected the physiographic panels will be re-engaged to work through the assessment of P Index performance and generate insight into the potential for regionally consistent approaches to P-based management.

Authors

Peter Kleinman, Research Leader, USDA-ARS Pasture Systems and Watershed Management Research Unit peter.kleinman@ars.usda.gov

D. Beegle, Z. Easton, A. Collick, Q. Ketterings, D. Fuka, T. Veith, A. Shober, S. Cela, M. Reiter, A. Allen, J. Liu and T. Basden

Additional information

Information on this project can be obtained by contacting the corresponding author.

Acknowledgements

This project is funded, in part, by a USDA-NRCS Conservation Innovation Grant.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Checking Ambition with Reality: The Pros and Cons of Different Approaches to Site Assessment

Purpose

This talk is intended to spark discussion over options related to site assessment for nutrient management. It will include a brief presentation followed by open discussion.

What did we do?

The revision of the USDA-NRCS national standard for nutrient management in 2011 was driven, in part, by inconsistencies in state phosphorus (P) indices, rekindling debates over standardizing indices at regional or national scales. Reasonable arguments exist for maintaining the status quo, which allows for state specific site assessment approaches, as well as for regional and national P Indices, which would take advantage of expertise, resources and technologies that may not exist locally. In addition, a diversity of site assessment approaches have now been proposed that differ from the original P Index. Understanding the benefits and limitations provided with these approaches is key to advancing site assessment for P management.

All site assessment tools are intended to identify critical source areas of P loss that should be targeted for improved management. The original P Index provided an elegant reduction of key factors affecting P loss from agricultural fields by categorizing factors into “transport” and “source.” More than a decade after the wholesale implementation of state P Indices in 47 US States, critiques of this approach range from inconsistency in their rating of P loss vulnerability, to differences in their recommendations, to poor or “clunky” links to site management.

What have we learned?

A variety of alternative approaches to site assessment have been proposed, most relying upon simulation models that produce an array of off-site metrics, most importantly, runoff P loads. These alternatives have been strongly advocated by their developers and by others interested in quantifying the effects of changing management, but have not yet replaced the original P Indices. Strong rhetoric has been employed in favor, and in opposition, to site assessment approaches. In general, supporters of the P Index argue that it is more of an educational tool, that should be “directionally correct” to affect change in management. Supporters of the modified fate-and-transport models argue that they too can be packaged to be educational and that they have the added benefit of projecting off site benefits. Concern exists over the ability of all site assessment tools to accurately quantify P loss or P loss potential.

Inconsistencies in site assessment approaches at geo-political boundaries (typically state lines but also physiographic and watershed divides) have led to proposals for regional or national approaches to P site assessment. Legitimate tension exists between the representation of unique, local conditions (physiographic or regulatory) and consistency to ensure fairness and accuracy. Past proposals to develop a national P Indexing framework from which local P Indices could be developed were intended to overcome this tension, but were unsuccessful due to local opposition and their top-down nature. Real conflicts are inevitable when state regulations are impinged, even in the name of regional consistency

Future Plans

While the P Index is decided strategic in its approach, a new crop of site assessment tools is emerging to address the day-to-day decision support tools of farmers. These tools employ short-term weather forecasting to identify the potential for runoff to occur following manure application, and range in their sensitivity from field scale to large watershed scale. In general, it is seen that these tools are complementary to the strategic site assessment tools, but, undoubtedly, opportunity exists for a merger of strategic and tactical approaches.

Authors

Peter Kleinman, Research Leader, USDA-ARS Pasture Systems and Watershed Management Research Unit peter.kleinman@ars.usda.gov

D. Beegle, Pennsylvania State University; D. Osmond, North Carolina State University; J. Lory, University of Missouri; P. Vadas, USDA-Agricultural Research Service; and A. Sharpley, University of Arkansas.

Additional information

This presentation is intended to underscore open discussion at the meeting on the subject of site assessment.

Acknowledgements

This presentation is the product of a national Conservation Innovation Grant aimed at promoting better coordination in nutrient management planning

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Wisconsin Producer Perspective on the Phosphorus Index

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Why Evaluate the P-Index from the Farmer’s Perspective?

The phosphorus index is a risk management tool, designed to evaluate the potential for runoff from a field based on the conditions and management of that field. Based on many years of work with farms in Wisconsin, the author sees the P-Index as valuable tool for comparing fields and management on the same farm and influencing choices that will lead to the lowest risk of runoff. The tool should not be used to compare between farms, as differing management and geography can cloud those comparisons. Another aspect of the p-index that causes concern is its use as a regulatory tool. When the p-index is applied from a distance–without contact with the farm or farmer, a disconnect can develop.

Author

Dennis Frame, University of Wisconsin drframe@wisc.edu

Additional Information

UW Discovery Farms http://uwdiscoveryfarms.org/

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

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Nutrient Management Standards – Making Them Work Where We Work

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Abstract

The economics and environmental impacts of livestock production cross watershed boundaries and affects both rural and urban populations. In particular, the issue of manure management has been the subject of debate and new policies in recent years as the non-point source discharge of nutrients and bacteria can be substantial if manure is not managed properly. Like most policies and rules, every five years the National Conservation Practice Standard (590) on Nutrient Management undergoes review and revision. This year, 2013, marks the initial year for adoption and implementation of state-specific and/or revised 590 standards across the United States. Despite “guiding” national standards and policies, there are different, unique approaches and tools used for nutrient management within different states and regions.

Why Discuss Nutrient Management Standards?

This session explores how different states are moving forward with nutrient management policies, standards and practices, and in particular, related to the NRCS 590 Standard. This session will include a panel discussion on unique adaptations by states to phosphorus indices, nitrogen leaching indices, winter application guidelines, air quality, and general nutrient management planning. The panel will also discuss if and how stakeholders have come together to develop these standards and practices. The discussion is also open to audience members wishing to share approaches and ideas. The session will conclude with a planning session to identify how we can, cooperatively, prepare for future policy and standard development, including discussion of collaborative research opportunities. This is a great opportunity to start building multi-state research projects to provide answers to manure management questions and issues that we might face in another five years.

Presenters

Erin Cortus, Assistant Professor, South Dakota State University erin.cortus@sdstate.edu and Nichole Embertson, Nutrient Management and Air Quality Specialist, Whatcom Conservation District, Lynden, Washington nembertson@whatcomcd.org

All presenters were invited to speak on the panel as experts on their State’s 590 revisions and/or adoption and implementation process. Their unique perspectives and processes will shed light on the regional differences in Nutrient Management and how it is affected by policy, social considerations, and regional resource concerns.

Laura Pepple, Livestock Extension Specialist, University of Illinois Urbana-Champaign

Melony Wilson, Animal and Dairy Science Public Service Representative, University of Georgia

Bonda Habets, Certified Crop Advisor, Washington State

James Sharkoff, State Conservation Agronomist, USDA-NRCS Colorado State

Handouts

Summary of Responses from National Survey

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

 

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