U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Environmentally Integrated Dairy Management Research: Madison, WI
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area Madison, Wisconsin U.S. Dairy Forage Research Center Environmentally Integrated Dairy Management Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Vadas, Peteritem
                                            Bolster, Carlitem
                                            GOOD, LAURA - University Of Wisconsin
  Submitted to: Soil Use and Management
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 5/23/2012
                                    Publication  Date: 3/12/2013
                                    Citation: Vadas, P.A., Bolster, C.H., Good, L.W. 2013. Critical evaluation of models used to study agricultural phosphorus and water quality. Soil Use and Management. 29:36-44.Interpretive Summary: This article uses recent research examples to evaluate potential problems when developing models to simulate agricultural phosphorus in the environment. Models are valuable research tools, but they need to be developed properly so they can make accurate predictions. First, a scientist must properly understand phosphorus cycling and movement to be able to develop an accurate model. However, a proper understanding does not guarantee that the equations used will give accurate predictions. Translating equations into computer code can also create model errors. Models must be structured to allow for validation with field data or there is little confidence they can predict phosphorus movement. It can be difficult to know why a model does not validate and when it should be changed or even rejected. Model development is often limited by data availability, but also by poor communication between field scientists and model developers. Currently, scientists may be concentrating too much on generating research data and not enough on using data to develop models.
                                Technical Abstract: This article uses examples from recent research to evaluate select issues related to developing models that simulate phosphorus in the environment. Models are valuable because they force scientists to formalize understanding of P systems and identify knowledge gaps, and allow quantification of P transfer when monitoring is not possible. Model development should follow a procedure from a perceptual model of qualitative understanding to a conceptual model of equations to a procedural model of code. There are few implications for a flawed perceptual model when publishing scientific articles, but an inaccurate perceptual model stands little chance of predicting reliably. Because many different model structures are possible, it is possible for a model to be perceptually correct but conceptually incorrect. Translation of conceptual equations into procedural model code can also create model errors. Many P models share the same equations, many of which may be 30 years old and should be updated to reflect current science. Furthermore, models may be applied in situations for which their algorithms are inadequate. Models must be structured to allow for validation with field data or there is little confidence they can quantify P transfer. It can be a challenge to understand why a model does not validate and know when a model should be rejected. Model development and validation are often limited by data availability, but also by poor communication between field scientists and model developers. There may currently be too great an emphasis on data generation and too little emphasis on model development.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov