Controlling runoff and erosion from your waterfront property: a guide ...
Evaluating Runoff Phosphorus Risk on Agricultural Lands ......Participating Farms Reduced Runoff P...
Transcript of Evaluating Runoff Phosphorus Risk on Agricultural Lands ......Participating Farms Reduced Runoff P...
Evaluating Runoff Phosphorus Risk on Agricultural Lands:
Pleasant Valley Experience
Photo: M Godfrey
Laura Ward Good
Wisconsin P Index
Photo: M Godfrey
Estimates average annual
P lb/acre/year delivered to surface water from field
Field
Annual P delivery to
stream (P Index)
Annual “field-edge” runoff
losses estimated for each crop
year: Sediment-bound P
Dissolved P from soil
Dissolved P from manure and
fertilizer
Feld to stream delivery ratio
Stream
Runoff
Erosion
WI P Index Basics Developed for Nutrient Management Planning
“Conservative” planning assumptions:
• Uses RUSLE2 erosion and runoff calculated for Dominant Critical Area for whole field
• Assumes continuous channelized flow similar to a grassed waterway
Does not account for P in gully erosion
For equations: wpindex.soils.wisc.edu
Good, L.W., P.Vadas, J.C. Panuska, C.A. Bonilla, W.E. Jokela, 2012. Testing the Wisconsin Phosphorus Index with Year-Round Field-Scale Runoff Monitoring. Journal of Environmental Quality 41:1730-1740.
X
=
RUSLE2
P Index calculator
WI P Index (P b/a/yr):
• Rotation Average
• Annual
Dissolved
Particulate
Erosion (sed t/a/yr)
P Trade (lb/fld/yr)
Uses predominant soil
for erosion and runoff
Nutrient application
rate calculator
Soil Test P and Organic Matter
Field Slope
Field Slope Length
Tillage
Rotation crops and yields
Manure Applications
P Fertilizer Applications
Downfield Slope to Surface Water
Soil Type
Distance to Surface
Water
Phosphorus Index
SnapPlus Inputs and Outputs Inventory
Calculations Results by field
Baseline P Index Distribution
Project watershed rotational P Index by acres
All > 6 down to 6, reduce loads by 1/4 All >3 down to 3, reduce loads by 1/2
Flat field (1% slope) in continuous corn silage with excessively high soil test P (200 ppm)
Example High P Loss Field
No one-size-fits-all solutions
Reductions went below runoff standards
First focus: Fields with P Index above 6 Second focus: Fields with P Index between 3 and 6
Reality: Farmers applied practices across many fields, not just high P Index fields
Participating Farms Reduced Runoff P Loss and Erosion
Acres
P Index
reduction
(lb/yr)
Erosion
reduction
(ton/yr)
No-till/reduced
till/residue
management
1840 3300 2000
Pasture systems
(stream crossings,
fencing, seeding)
315 1100 100
Estimated average annual runoff P and erosion reductions in Pleasant Valley from cost-shared managements: Implementation period (2010-2013) compared to baseline (2006-2009)
Estimated average annual runoff P losses for
participating farms, baseline (2006-2009) and 2013
Participating farms cut runoff P losses in half
Watershed tracking finding:
Runoff P losses increased on other farms
Estimated P delivery from all agricultural acres in watershed was reduced 12%
Largest increases were from grassland conversion to cropland
Summary
WI P Index inventory and tracking allowed project to: • Identify croplands and pastures with higher
P runoff contributions to stream • Identify alternative managements • Estimate runoff phosphorus reductions with
changing practices