Assessing Whole-Farm Phosphorus Loss from WI Dairy Grazing Farms

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1 Assessing Whole-Farm Phosphorus Loss from WI Dairy Grazing Farms Peter Vadas, Mark Powell, Geoff Brink USDA-ARS Dairy Forage Research Center, Madison, WI Dennis Busch UW-Platteville Pioneer Farm, Platteville, WI

2 Agriculture Impacts Water Quality P loss from farms promotes algae and plant growth in bays, lakes, rivers and degrades water quality for drinking, recrea?on, industry Lake Mendota, Madison, WI

3 Dairy Farms and P Loss Many sources, including cropland, grazed pastures, and outdoor lots, (feedlots, barnyards, over-wintering, exercise areas) Need to efficiently and accurately assess P loss from all sources to effectively target limited remediation resources There is lack of data and modeling tools to assess impact of grazed pastures and lots within whole-farm context

4 Free-stalls Stanchions 34% Collected manure 11% 66% Non- collected manure 89% Powell et al., 2005

5 Where manure goes uncollected Non- vegetated barnyards Non- vegetated barnyards (near barn) Vegetated holding areas (non- pasture) Feed bunk areas

6 Project Objectives Monitor P loss in runoff from 8 beef and dairy grazed pastures at UW Platteville Pioneer Farm Use runoff data to validate ability of Annual P Loss Estimator (APLE) model to predict P loss in runoff from grazed pasture Use APLE to simulate annual P loss from 4 WI grazing farms and determine relative impact of pastures and lots to whole-farm P loss. Funding provided by WI DATCP GLCI program

7 Pioneer Farm Pastures 4 basins in 18 acre pasture with beef; 4 basins in 15 acre pasture with nonlactating dairy Cattle had free access May-November

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9 Runoff Monitoring Results 20 runoff events between August 2010 and May 2012; 15 events due to snowmelt Year Precip. Runoff Erosion Total P Dissolved P in in ton/ac lb/ac lb/ac Sediment Dissolved P Total P NH 4 -N NO 3 -N Total N mg/l Winter Non-winter

10 Predicting Runoff P with APLE Add short description of APLE, with brief details about validation with 18 studies

11 Pasture Runoff P and APLE Predicted Annual TP Loss (kg/ha) Literature Studies Pioneer Farm y = 1.0x r² = Measured Annual TP Loss (kg/ha) Data from 19 published studies monitoring P loss from cattlegrazed pastures (FL, AR, TX, OK, OH, Australia, New Zealand, Ireland)

12 Barnyard Runoff P and APLE Predicted Annual TP Loss (kg/ha) Literature Studies Pioneer Farm y = 0.95x r² = Measured Annual TP Loss (kg/ha) Adapted APLE for barnyards; data from 12 published U.S. studies monitoring P loss cattle feedlots, barnyards

13 Assessing P Loss on 4 WI Grazing Farms Conducted rapid-assessment surveys on 4 farms during winter, spring, and fall to capture seasonal management information Feeding, cow location in space and time, manure collection and use, land use and crop rotations Developed annual management scenarios that were input into models Used SNAP+ to estimate runoff and erosion for all land uses on farms Used APLE to estimate P loss from cropland, pasture, barnyards, cattle lots to develop whole-farm loss estimates

14 Location of 4 WI Grazing Farms Athens Edgar Richland Center Blanchardville

15 Farm Management Blanchardville Richland center Edgar Athens Total cattle Lactating cows Cropland acres Pasture acres Slopes 6-30% 6-30% 0-6% 0-6% Manure Storage Lots Barnyard Overwinter Year-round exercise

16 Lots (1.5) Pastures (72) Hay (67) 175 acres 2.4 lb/ac P Loss Blanchardville Corn Silage (17) Hay- seed (17) Whole-Farm P Loss Hay (70) Barnyard (0.3) Lots (2.8) Pastures (220) Corn Silage (80) Richland Center Hay- seed (40) 1.6 lb/ac P Loss 423 acres Hay (80) Athens Edgar Lot (2) Pastures (220) Barnyard (0.2) Lots (0.5) Pastures (170) Corn Silage (30) 325 acres 1.2 lb/ac P Loss Winter Pasture (28) Hay (33) Hay- seed (17) Corn Grain (30) 281 acres 1.6 lb/ac P Loss

17 Summary APLE can reliably estimate P loss in runoff from all areas on cattle farms, given good estimates of runoff and erosion Rapid farm surveys and user-friendly models can identify areas on farms of greatest P loss P loss from grazing farms is generally low, especially from pastures and established hay, but For cropland, greatest P loss from areas with exposed soil and related erosion Concentrated animal areas can have very high P loss, and be 20-60% of total farm loss, depending on lot management and other land uses