Winter Alert: Limited Manure Application Conditions
This fall has been a challenge for many growers, with delayed harvest due to wet soil conditions followed by colder than usual temperatures. These adverse conditions are also affecting manure application. Iowa Manure Management Action Group, also known as IMMAG, has provided producers with some reminders on how to manage manure application this winter.
Due to a law passed in 2010, there are special limits to applying manure to frozen ground. This law pertains to liquid manure application for operations with more than 500 animal units. Application is prohibited from December 21 through April 1 on snow covered ground as well as February 1 through April 1 on frozen ground.
Surface Application
If frozen, impenetrable ground occurs before these time frames, operations may be able to switch from injection to surface application. Before making this decision, two items must be checked off your list. First, if you claimed injection points in MasterMatrix, you must request permission from the Iowa DNR to switch to surface application. Second, there may be application restrictions on frozen or snow-covered ground if you have an NPDES permit or NRCS comprehensive nutrient management plan, so check these documents thoroughly.
If you decide to switch to surface application, updating the volatilization correction factor may be necessary. Table 2 of PMR 1003 in “Using Manure Nutrients for Crop Production” is a good resource in adjusting this volatilization factor.
Being aware of setback distance requirements is vital as well. Although injection/incorporation have setback distances of 0, it can vary with surface application. With liquid manure, 750 feet for residential and public use areas, 200 feet for water sources, and 800 feet for high quality water resources are the current requirements. Get more information on setback distances here.
Tips for winter manure application:
- Pay attention to current and upcoming soil and weather conditions
- Do not apply before snowmelt or rainfall activity
- Apply to level ground or areas with controlled erosion to prevent nutrient loss
- Stick to setback distance requirements
- Sleeve surface tile inlets to keep runoff out of tiles
Source:
“IMMAG Updates.” IMMAG-Iowa Manure Management Action Group, Iowa State University Extension & Outreach , Nov. 2018, www.agronext.iastate.edu/immag/newsupd.html.