IMMAG Updates

March 2016

Welcome to the monthly update for the Iowa Manure Management Action Group (IMMAG) Web site. This update is provided as a service to inform you about changes made to the IMMAG Web Page or items of interest dealing with manure management and air quality from animal feeding operations. If you wish to subscribe to this mailing please click here. You may also view this update with direct links on the CURRENT NEWS site on IMMAG.

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Spring Manure Application Decisions:
photoStoring manure reduces or eliminates the need to collect and spread manure on a daily basis. Perhaps more importantly, storing manure provides the capacity for the farm to land apply the manure at a time that is compatible with both the climatic and cropping characteristics of the land receiving the manure. In Iowa, this often leaves us with two windows for manure application; in the spring after the soils start to warm up but before we plant crops for the up-coming year and/or in the fall after our crops have been harvested but before the soils freeze.

This brings up the question, which is better, spring or fall manure application? Applying in the spring leaves less time for decomposition of organic material in the manure and conversion of manure nitrogen into nitrate before the crop is up and actively growing. This can be a good thing as it can reduce the loss of nitrate. However, spring is often a busy time with planting and other fieldwork, and any delay caused by waiting for manure application might reduce yield potential. Additionally, in the spring we are often dealing with wet soils that might make soil compaction a concern. If we apply in the fall, it gives microbes in the soil time to decompose the manure, which can make the manure nutrients available to the crops as soon as they are planted. On the other hand, it gives us more time for nitrogen loss before the crop is up and growing. In the end balancing both the agronomic, time availability, and environmental factors all come into play when making this decision.

There is some data available to compare spring versus fall nitrogen and manure application. A recent summary of nitrogen application timing was prepared as part of the Iowa Nutrient Reduction Strategy science assessment. The summary was not specific for manure, but was geared at how timing of nitrogen application influenced losses through leaching and crop production. They estimated that switching from fall fertilizer application to a pre-plant nitrogen application in the spring would reduce nitrogen losses by 6% on average. These studies also indicated that switching from fall application to spring application would increase corn yield by 4% on average. In a study that evaluated the impact of swine manure timing on crop yield performed near Ames from 1996 through 2001 found that fields receiving spring manure yielded about 2.5% more corn than the field getting fall applied manure. So if you find yourself needing to apply manure this spring to ensure you will have enough storage to make it to the fall, take heart knowing it can still provide your corn the nitrogen it needs and might even help keep a little nitrate out of our tiles and streams.

Bigger pigs, more manure?
photoMore of our swine operations are choosing to apply manure in the spring and fall than ever before. There are lots of potential reasons for this - reduced nitrate loss from spring application, some tough weather conditions in the fall making it hard to get manure application completed, foaming in the manure pit resulting in less usable storage, and maybe bigger pigs resulting in more manure. Finish weights for our pigs seem to be continually getting larger. Should we be building bigger pits to make sure we have the storage we need to make it to the next year? Look at The Manure Scoop to see what influence bigger pigs might be having on our facility design.

What manure application records to I need to keep?
Records and paperwork; I know manure application happens during a busy portion of the year and we all have lots to get done, but keeping accurate records about your manure application is the law. Beyond that, when it comes time to assess how your manure and fertility program performed, you want to make sure you have the right information recorded to know that you did and any challenges you faced.

Confinement site manure applicators who have manure management plans need to have records on hand for the last five years of manure application (1) the methods and rates of manure application, (2) the date when manure was applied, and (3) the location of the field and the number of acres receiving manure. Commercial manure applicators also need to keep records. In this case that need three years of records on (1) instructions for manure application, like the manure management plan, (2) dates that the manure was applied or sold, (3) the manure application rate, and (4) the location of the field manure was applied to (1/4 section, section, township, range).

I would encourage you to make additional notes about the application as well: what were the soil and weather conditions at the time of the application, were there wet areas in the field that you had to skip, did you notice any injectors plug during the application, and similar thoughts. Having this information (or even an as applied map) might let you look at your yield maps to evaluate how your fertility program worked for you and help with making decisions next year.

Iowa DNR Spill Number
photoManure application season is fast approaching, are you ready? Remember if you have a manure spill it is required that you report it to the Iowa DNR within 6 hours of the spill. If making the call during typical business hours (or there about) try calling your local field office:
Manchester: 563-927-2640
Mason City: 641-424-4073
Spencer: 712-262-4177
Atlantic: 712-243-1934
Des Moines: 515-725-0268
Washington: 319-653-2135

For spills on weekends or during non-business hours use 515-725-8694 to reach the Iowa DNR 24-hour spill line. Make sure you have this number updated in your phone and in the binder of important information of all that useful manure information you keep (like the manure management plan, site specific application instruction) for each facility you apply at.


Spring manure application season is quickly approaching; did you get your annual certification/continuing education completed? If you are still in need of training, there are still several options for getting your manure training completed. You can get certification by: 1) contacting your County Extension Office to make an appointment to watch the appropriate training video; 2) contacting your local DNR field office to schedule an appointment to take the certification exam; or 3) completing your training on-line!

To utilize the on-line option, you will need a computer, smartphone, or other internet capable device and an internet connection that will support streaming video. To find the online training site, please go to MAC E-Learning. Still have questions about the on-line training options? Here is an article that answers the questions we get the most frequently.

A quick reminder about who needs manure applicator training.

  • If you are in the business of hauling or applying manure, you will need a commercial manure applicator certification.
  • If you haul/apply manure from a confinement animal feeding facility with more than 500 animal units, you will need a confinement site manure applicator certification. You must complete your annual manure application certification training to keep your three-year license current.


The IMMAG Events page is a compilation of manure management related events. Please check the events page often for new listings.

Integrating Grazing into Cropping Systems: On March 8th at 1:00 PM the USDA ARS is hosting a webinar that will describe opportunities to integrate crop and livestock systems and how soil health responds to grazing of cover crops and perennial forages.

Antibiotic Resistance and Animal Agriculture: The Livestock and Poultry Environmental Learning Center is holding a webinar on March 25th at 1:30  on Antibiotic Resistance and Animal Agriculture.


Wishing you a happy spring and safe hauling,

Dan Andersen
(515) 294-4210
Twitter: @DrManure

Angie Rieck-Hinz
(515) 231-2830
Twitter: @iowamanure

Iowa Manure Management Action Group

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