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University of Wisconsin–Madison
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The Wisconsin Idea Database
The Wisconsin Idea in Action

Wisconsin Phosphorus Index

The Wisconsin Phosphorus (P) Index (WPI) is a planning tool for managing cropland and pastureland. It uses information that is readily available to farmers to quantify the risk of phosphorus delivery to surface water in runoff from a specific field under varying management conditions. The WPI algorithms are based on Wisconsin research and have been validated with field runoff monitoring by UW-Extension (Discovery Farms) and UW-Platteville (Pioneer Farm). The WPI can be used to target areas that are contributing the greatest amount of P to local surface water and also to evaluate the runoff P reduction potential of alternative management strategies.

Outcomes

The WPI is referenced in state runoff standards that apply to all agricultural land in Wisconsin as a tool that should be used for evaluating the risk of phosphorus in runoff from cropland and pastures. The WPI is calculated automatically in the SnapPlus nutrient management planning software, so farmers planning manure and fertilizer applications for cropped fields will automatically receive an indication of the relative risk of their field-level management practices contributing to phosphorus in runoff. Agricultural nonpoint runoff projects are using the WPI for targeting conservation efforts and estimating reductions in phosphorus runoff. The WPI is part of the state's new Watershed Adaptive Management and Water Quality Trading Programs.

Project Website

Focus Areas

Project Leader

Laura Good
Associate Scientist

Department/Unit
Soil Science
School or College
College of Agricultural and Life Sciences

Counties 72 total

Map of Wisconsin Highlighting Adams, Ashland, Barron, Bayfield, Brown, Buffalo, Burnett, Calumet, Chippewa, Clark, Columbia, Crawford, Dane, Dodge, Door, Douglas, Dunn, Eau Claire, Florence, Fond du Lac, Forest, Grant, Green, Green Lake, Iowa, Iron, Jackson, Jefferson, Juneau, Kenosha, Kewaunee, La Crosse, Lafayette, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Marquette, Milwaukee, Monroe, Oconto, Oneida, Outagamie, Ozaukee, Pepin, Pierce, Polk, Portage, Price, Racine, Richland, Rock, Rusk, Saint Croix, Sauk, Sawyer, Shawano, Sheboygan, Taylor, Trempealeau, Vernon, Vilas, Walworth, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood, Menominee Counties. Copyright © 2015 Highsoft AS, Based on data from The United States Census Bureau Map of Wisconsin Highlighting Adams, Ashland, Barron, Bayfield, Brown, Buffalo, Burnett, Calumet, Chippewa, Clark, Columbia, Crawford, Dane, Dodge, Door, Douglas, Dunn, Eau Claire, Florence, Fond du Lac, Forest, Grant, Green, Green Lake, Iowa, Iron, Jackson, Jefferson, Juneau, Kenosha, Kewaunee, La Crosse, Lafayette, Langlade, Lincoln, Manitowoc, Marathon, Marinette, Marquette, Milwaukee, Monroe, Oconto, Oneida, Outagamie, Ozaukee, Pepin, Pierce, Polk, Portage, Price, Racine, Richland, Rock, Rusk, Saint Croix, Sauk, Sawyer, Shawano, Sheboygan, Taylor, Trempealeau, Vernon, Vilas, Walworth, Washburn, Washington, Waukesha, Waupaca, Waushara, Winnebago, Wood, Menominee Counties. Copyright © 2015 Highsoft AS, Based on data from The United States Census Bureau United States of America 2 U.S.A. Northern America North America USA US 23424977 North America us US 0 US.WI WI|Wis. 2347608 East North Central US55 WI Wisconsin United States of America State Midwest -89.5831 Wisconsin 44.3709 Wisconsin, US, United States State us-wi WI 55111 Sauk 0.50 0.41 us-wi-111 SA 55049 Iowa 0.50 0.50 us-wi-049 IO 55003 Ashland 0.31 0.67 us-wi-003 AS 55007 Bayfield 0.41 0.57 us-wi-007 BA 55113 Sawyer 0.43 0.50 us-wi-113 SA 55021 Columbia 0.62 0.50 us-wi-021 CO 55001 Adams 0.50 0.43 us-wi-001 AD 55085 Oneida 0.50 0.40 us-wi-085 ON 55099 Price 0.50 0.50 us-wi-099 PR 55017 Chippewa 0.58 0.50 us-wi-017 CH 55019 Clark 0.50 0.50 us-wi-019 CL 55087 Outagamie 0.50 0.50 us-wi-087 OU 55115 Shawano 0.31 0.50 us-wi-115 SH 55069 Lincoln 0.50 0.50 us-wi-069 LI 55055 Jefferson 0.50 0.50 us-wi-055 JE 55027 Dodge 0.50 0.50 us-wi-027 DO 55125 Vilas 0.49 0.52 us-wi-125 VI 55041 Forest 0.50 0.69 us-wi-041 FO 55047 Green Lake 0.49 0.50 us-wi-047 GL 55137 Waushara 0.50 0.50 us-wi-137 WA 55045 Green 0.50 0.50 us-wi-045 GR 55105 Rock 0.50 0.51 us-wi-105 RO 55127 Walworth 0.50 0.50 us-wi-127 WA 55005 Barron 0.50 0.50 us-wi-005 BA 55093 Pierce 0.58 0.50 us-wi-093 PI 55033 Dunn 0.49 0.50 us-wi-033 DU 55107 Rusk 0.43 0.50 us-wi-107 RU 55119 Taylor 0.50 0.50 us-wi-119 TA 55101 Racine 0.50 0.31 us-wi-101 RA 55053 Jackson 0.50 0.59 us-wi-053 JA 55035 Eau Claire 0.50 0.50 us-wi-035 EC 55083 Oconto 0.33 0.37 us-wi-083 OC 55009 Brown 0.43 0.52 us-wi-009 BR 55079 Milwaukee 0.50 0.74 us-wi-079 MI 55089 Ozaukee 0.49 0.38 us-wi-089 OZ 55103 Richland 0.50 0.50 us-wi-103 RI 55023 Crawford 0.53 0.41 us-wi-023 CR 55133 Waukesha 0.50 0.50 us-wi-133 WA 55057 Juneau 0.39 0.71 us-wi-057 JU 55123 Vernon 0.43 0.50 us-wi-123 VE 55025 Dane 0.50 0.50 us-wi-025 DA 55051 Iron 0.48 0.52 us-wi-051 IR 55135 Waupaca 0.40 0.50 us-wi-135 WA 55139 Winnebago 0.50 0.50 us-wi-139 WI 55061 Kewaunee 0.35 0.50 us-wi-061 KE 55097 Portage 0.59 0.50 us-wi-097 PO 55015 Calumet 0.50 0.50 us-wi-015 CA 55063 La Crosse 0.62 0.50 us-wi-063 LC 55073 Marathon 0.50 0.50 us-wi-073 MA 55013 Burnett 0.57 0.58 us-wi-013 BU 55121 Trempealeau 0.55 0.50 us-wi-121 TR 55129 Washburn 0.50 0.50 us-wi-129 WA 55091 Pepin 0.18 0.76 us-wi-091 PE 55141 Wood 0.50 0.50 us-wi-141 WO 55043 Grant 0.66 0.47 us-wi-043 GR 55065 Lafayette 0.50 0.50 us-wi-065 LA 55117 Sheboygan 0.50 0.50 us-wi-117 SH 55077 Marquette 0.50 0.50 us-wi-077 MA 55067 Langlade 0.35 0.40 us-wi-067 LA 55078 Menominee 0.50 0.50 us-wi-078 ME 55131 Washington 0.50 0.50 us-wi-131 WA 55109 St. Croix 0.50 0.50 us-wi-109 SC 55037 Florence 0.50 0.50 us-wi-037 FL 55039 Fond du Lac 0.50 0.51 us-wi-039 FD 55081 Monroe 0.50 0.50 us-wi-081 MO 55011 Buffalo 0.60 0.35 us-wi-011 BU 55029 Door 0.56 0.57 us-wi-029 DO 55095 Polk 0.57 0.50 us-wi-095 PO 55075 Marinette 0.46 0.54 us-wi-075 MA 55031 Douglas 0.50 0.56 us-wi-031 DO 55059 Kenosha 0.50 0.50 us-wi-059 KE 55071 Manitowoc 0.40 0.50 us-wi-071 MA

This project was last updated on May 22, 2019. Do you have an update for this project? Find out how to contribute.