For more: http://www.extension.org/67684 The Wisconsin Discovery Farms Program was one of the first on-farm evaluation projects to identify the risk of manure applications in the late winter period. Data from several of our farms have shown that manure applied during February and March has an increased risk of running off and contributing to high nutrient losses in surface water. This data has been used to justify the establishment of recommendations, rules and regulations on winter manure spreading. But, do bans on winter manure spreading (spreading on frozen or snow covered ground) actually reduce the risk of manure runoff? A close evaluation of the data indicates that spreading during early winter (November - January) is much different than during late winter when frost can extend deeper and be more solid in the soil profile. Total winter application bans also increase the volume of manure that needs to be stored and increase the risk of runoff during the spring spreading season.

1. Amber Radatz
UW Discovery Farms
April 3, 2013
Will Spreading Bans Reduce
Winter Runoff Events?

2. Key Lessons from Discovery
Farms
 Timing, timing, timing
 Management decisions really do matter
 Losses can vary greatly year to year based on
weather, location and management decisions
 Sound conservation is still sound conservation

3. Wintertime runoff
 On average, 50% of runoff while soil is frozen
 Can be 100% of total annual runoff depending
on conditions
 Mostly February and March
 March:
 100% frequency
 1/3 of total annual runoff
 Risk for runoff in April, May and June is similar to
that of January and February

4. Runoff Timing
Average % of
Annual
Runoff
Runoff
Freque
ncy
October 3% 23%
November <1% 15%
December 1% 35%
January 4% 50%
February 16% 58%
March 34% 100%
April 4% 54%
May 12% 38%
June 19% 42%
July 3% 42%
August 3% 19%
September <1% 19%Source: Precipitation-Runoff Relations and Water-Quality Characteristics at Edge-of-Field Stations, Discovery Farms and Pioneer Farm, Wisconsin, 2003–
8.
55% of annual runoff
35% of annual runoff

5. Management Decisions
 Shorter time between manure application and
runoff event = greater potential for nutrient
losses
 Liquid dairy and solid beef applications shortly
before runoff increased nutrient loss
OR

6. Winter unpredictability
February 2011
February 2012

7. Winter/Spring unpredictability
March 27, 2013

8. So what about banning spreading
based on dates?
 Spreading bans don’t stop runoff events, people
do
 Understanding the key factors for runoff is the
best way to reduce nutrient and sediment losses
 It comes down to:
 Our job: giving producers the best information
available on runoff timing, effects of manure
application at different times
 Your job: using that information to make the best
decisions possible

9. Key Recommendations
 Understand factors for runoff and assess the
situation on your farm
 Winter runoff:
 Dramatic and rapid warming causing snowmelt
 Rain on frozen or snow covered ground
 Spring runoff:
 Saturated soils
 Consecutive rain events

10. Key Recommendations
 Manage manure storage to avoid high-risk
time periods
 Save some less risky fields for the most risky
time periods
 Work with local land and water professionals
to identify areas on your farm suitable for
stacking or spreading
 Decide if some amount of storage is right for
you

11. Amber Radatz
aradatz@wisc.edu
www.uwdiscoveryfarms.org
Thank you!