COLUMNISTS

It’s time to have your plan ready for manure applications in 2021

Erica Gentry
It is important to understand the conditions that lead to runoff and heightened risk for nutrient loss, so farmers can reduce runoff and water quality impacts.

As a busy springtime fast approaches, it’s time to have your plan ready for manure applications in 2021.

It is important to understand the conditions that lead to runoff and heightened risk for nutrient loss, so you can reduce runoff and water quality impacts. Small tweaks can lead to big benefits for your crops and the environment. Keep nutrients where they are most beneficial by following these steps throughout the season.

Before planting

Discovery Farms has monitored water quality on Wisconsin Farms since 2001. Our edge-of-field monitoring results show that March is THE month with the most surface runoff as seen depicted in thegraph.

Discovery Farms Wisconsin and Minnesota average edge-of-field surface runoff values by month.

In Wisconsin, during March, we see higher amounts of surface runoff taking place primarily due to warming temperatures leading to snowmelt or precipitation on frozen or saturated soils. For this reason, take extra caution if you need to spread manure during this risky time period.

The Runoff Risk Advisory Forecast is a great place to check before you spread. This live map utilizes models and the current weather forecast to bring you your current risk for spreading. If your risk appears to be high but you are in a need-to-spread situation due to limited storage, work with your local conservation professionals to identify fields with lower risk of runoff and utilize these areas.

Growing season

Our monitoring suggests that June is the second highest month for surface runoff values based on elevated amounts of precipitation coupled with limited soil cover and an unestablished crop canopy. Having an established crop in the field helps to absorb and contain water in the field before it has a chance to leave as runoff.

Our monitoring suggests that June is the second highest month for surface runoff values based on elevated amounts of precipitation coupled with limited soil cover and an unestablished crop canopy.

Make sure you also understand your crop fertility needs through the growing season. Base crop nutrient decisions on soil test results and research-based recommendations. Be sure to accurately credit N-P-K delivered with livestock manure. If the crop doesn’t need it, don’t put it on.

If you are spreading manure on tile drained land, be sure you are using best management practices. Look for dry, cracked soil (especially if you farm on heavy clay soil types). Dry soil cracking and earthworm macropores can create unhindered openings from the soil surface down to tile so use reduced rates to allow the soil cracks to seal shut during dry conditions.

After harvest

Wait to apply manure until soil temperatures have cooled down below 50 degrees F. Life in soil is much more active in September than in December. When manure is applied while nitrifying bacteria are still active, nitrogen concentrations in tile lines increase. If you don’t have tile lines, that leached nitrogen could make its way towards groundwater sources.

If you are able to apply manure into a living crop, like an established cover crop stand, it can take up some of the nitrogen in the manure before winter, reducing the risk of loss to water resources. A cold-hardy cover crop is also a great way to provide some erosion control in the fall and following spring. For a deeper look into how cover crops and manure interact, see this article written by Dr. Matt Ruark at http://bit.ly/3stb0HS

For more resources on manure management and water quality, visit the newly redesigned Discovery Farms website www.uwdiscoveryfarms.org and click on the “Resource Library”. Our research is meant to be used by people like you and we are always open to your questions and suggestions. 

Erica Gentry

Erica Gentry is the Discovery Farms Farmer Network and Communications Coordinator and can be reached at Erica.gentry@wisc.edu.

UW Extension