Project collaborators: Laura Ward Good, Katie Songer, Matt Diebel, John Panuska, Jeff Maxted, Pete Nowak, John Norman, K.G. Karthikeyan, Tom Cox, Water Resources Management Class, UW-Madison; Pat Sutter, Duane Wagner, Curt Deihl, Dane County Land and Water Resources Department; Jim Leverich and Karen Talarczyk, UW- Extension, and Faith Fitzpatrick, Rebecca Carvin and Dave Graczyk, USGS, Funding Partners: The Nature Conservancy, Wisconsin NRCS, WI DATCP, WI DNR, USGS Research linking P Index Values to Stream Phosphorus Yields

Wisconsin P Index Estimate of annual P delivery from a given field using readily available information and assuming average weather Field P delivery to stream (P Index) Annual edge-of-field runoff losses (Annual sediment-bound P + Annual dissolved P) Total P delivery ratio x = Stream Units are lb per acre per year

WBI Hypothesis Targeting watershed implementation efforts to the fields that contribute the most nutrients to water is an effective way to improve water quality. And specifically…. Reducing all cropland rotational average P Index values in a watershed below the target maxima (6), will result in measurable water quality changes.

WBI Pilot Project: Testing surface water quality effects of targeted P management strategies Reference Treatment

P Index Map

How do we know if the project succeeds?

Hypothesis Reducing all cropland rotational average P Index values in treatment watershed below the target maxima (6), will significantly reduce the ratio of treatment watershed TP yields to reference watershed TP yields.

Paired Watershed Comparison Sediment Yields - WY2007 and WY2008

Paired Watershed Comparison Phosphorus Yields - WY2007 and WY2008 With April and June 2008

Paired Watershed Comparison Sediment Yields - WY2007 and WY2008 with April and June 2008

Paired Watershed Comparison Dissolved P Concentrations - WY2007 – WY2008

Monthly Precipitation

Monitoring Results Summary WatershedPhosphorus Sediment Yield 2007 Treatment1 lb/acre0.2 T/acre Reference0.6 lb/acre0.1 T/acre 2008 Treatment1.2 lb/acre0.2 T/acre Reference1.0 lb/acre0.3 T/acre

Treatment Watershed Land Use Agriculture Open Land Woodland CRP

Land Use Inventoried

Average: 39 ppm Min: 3 ppm Max: 383 ppm Soil Test P

Pleasant Valley Watershed P Index Values Rotation Average P Index (lb P/acre/year) Average: 4 Min: 0.1 Max: 45

Soil Test PP Index

P Index Distribution 7%9%84% 59 % of load Amount above 6 is 30% of total load

Annual P Index Distribution from Mead Lake 67% acres, 35% P load 26% acres, 42% P load 7% acres, 23% P load

Pheasant Branch P Load Distribution C. Anderson

Pheasant Branch P Load Distribution C. Anderson

Missing P Loss Sources Barnyards Some dry lots, pastures Lanes, other places where uncollected manure goes Animals with direct access to streams P in sediment eroded from flow channels Construction sites Stream bank erosion

Example Farm Dairy farm, animal housing not in watershed Almost all fields have: Soil test P > 50 Soil loss > T P Index > 6 Rotation: 3 yr corn silage or 2 yr corn silage & 1 yr grain, + 3 yr alfalfa Tillage: Fall chisel plow To get all fields below T and P I < 6: 1) No-till 2) Add grass to alfalfa mix 3) Never grow more than 2 yrs of silage

Comparison of P Index Values for Continuous Corn Silage Managements, Pheasant Branch, C. Anderson

Reducing Soil Loss vs. Reducing Soil P

Current Project Efforts Dane County initiating work with farmers, targeting high P loss farms first Dane County assessing barnyards (model?) Economic evaluation of management alternatives for selected farms Research on P transport Statistical analysis of rotational and average annual P Index distribution, development of screening tool, sampling protocol (Katie Songer’s talk)

Economic/Environmental Tradeoffs!!! Farm Management/Economics provides an integrated framework for assessing these tradeoffs in the context of particular farms/farmers. Many Nutrient BMPs Involve “Optimal” BMPs provide Win/Win (economic/environmental) opportunities to the farm/farmers: improved profits with improved NMP. In Non-Win/Win situations, farm management/economics can help to identify and rank least-cost practices to attain NMP objectives. On-Farm Economics Dr. T. Cox, UW-Madison and J. Leverich, UW-Extension

Research strategies to link P Index to water body P yields

Acceptable P delivery Area-weighted average P Index (lb/acre) Average stream P yield (lb/a) P Index Threshold What P Index threshold is compatible with acceptable P delivery?

Considerations May take years for land use changes to result in measurable drop in P yields because of P stored in flow channels Agricultural land use management is not static Need to take adaptive management approach, commit to continued monitoring and reassessment

Summary Phosphorus loss potential is much greater on some fields than others in watershed We are testing the hypothesis that implementing changes to reduce P lndex values for the highest P loss areas in a watershed will improve water quality Use of the P Index to evaluate potential P loss reductions allows management flexibility