IMMAG Updates

February 2017

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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Late Winter Manure Application

Figure 1. Carefully select manure application days in the early spring as quick snowmelts or rainfall events may result in runoff and nutrient loss - click to enlargeAs spring approaches, make sure to watch the forecast prior to manure application for predicted rainfall, snow, or warming conditions that could result in snow melt or runoff. A 1994 study by Iowa State University, showed the greatest risk for runoff occurs when manure is surface applied on top of snow in the late winter. Waiting to apply manure until the snow has melted can reduce nutrient losses and water quality impacts. In general, nutrient losses and surface water pollution can be reduced as the time between application and runoff increases.
Additionally, if you do apply manure in late winter:

  • Apply manure to flat slopes
  • Stay away from tile intakes, creeks, streams, and other surface water
  • Follow separation distances
  • Do not apply in a grassed waterway
  • Avoid areas that drain to surface tile intakes
  • Follow all regulations specific to your manure type

Master Matrix Approved by 88 Counties

Figure 2. The Master Matrix is a tool often used in the siting and permitting of new confinement livestock facilities in Iowa. The example above shows a confinement cattle finishing building - click to enlargeThis year, 88 of Iowa’s 99 counties approved the use of the master matrix to evaluate applications for large animal confinement operations construction permits. Counties that adopted the master matrix require that producers must meet higher standards than other permitted facilities when building, expanding, or modifying a totally roofed facility. Prior to construction approval, producers earn points for choosing sites and using practices that reduce impacts on the environment and community in the areas of air, water, and community impacts to pass the master matrix. Find more information about the master matrix at the Iowa DNR website.

Putting an economic value on a manure storage

Often times we look at a manure storage as something we have to do to help protect the environment or because regulations say we must. However, is there more to it than that? This month’s Manure Scoop looks at how a manure storage impacts manure value and if an economic argument can be made to support storage construction.

Phosphorus Transport from Manure

Figure 3. Comparison of phosphorus loss from a rainfall event from fields receiving 100 lb P2O5 per acre from various fertilizer sources including beef cattle manure, poultry manure, liquid swine manure, and DAP fertilizer  - click to enlargeThis past month has been filled with solid manure applicator trainings. We’ve had the opportunity to have Drs. Antonio Mallarino and Mazhar Haq, ISU agronomy department, present their work on phosphorus management. This presentation was extremely informative with discussions relevant to balancing fertility management and water quality challenges, why transport factors need to be considered along with soil test concentrations, and it had specific information relevant to manure application decisions and phosphorus management. A couple of which we wanted to specifically point out.

Manure is often a heavy point of discussion when it comes to water quality. It’s important to look carefully at what the research says and when we can spread the message of how valuable a resource manure can be for fertility management, and in some cases, how its use helps protect water quality. For example, in one of the studies Drs. Mallarino and Haq presented, they compared phosphorus loss from a field receiving 100 pounds per acre of P2O5 from either beef cattle manure, poultry manure, liquid swine manure, or DAP. A few things to note in all cases, less than 2% of the applied phosphorus was lost in the runoff event, but all the manures, and especially the solid manures, lost substantially less than the DAP fertilizer.

Figure 4. Impact of fertilizer source, runoff timing, and incorporation versus surface application on phosphorus losses in runoff. - click to enlargeHowever, as we pick the best days and techniques for manure and fertilizer management, it is important to consider both weather conditions and management practices we can use to reduce phosphorus losses. In a follow up study, they evaluated the impact of runoff event timing and tillage on phosphorus loss from the same fertilizer sources. In this case, their results showed that if a runoff event was expected, incorporation or injection was strongly recommended to reduce nutrient loss from the DAP and liquid swine manure application, but it had little impact on the poultry manure runoff losses. Timing of the first runoff event was critical. With more time for the phosphorus in the manures to interact with the soil before the first runoff event, it greatly reduced losses.


The Livestock and Poultry Environmental Learning Center has partnered with the Manure and Soil Health team to bring you four great roundtables to improve our understanding of: current knowledge, critical and emerging issues for which there are knowledge gaps, and information needs of farmers and their advisors. Information about the remaining roundtable is below.

Manure and Cover Crops - March 9, 2017

The roundtable will be held at 11 central, Noon eastern. Register at: or

How Do I Participate?

  • ANY TIME between now and the webcast, go to and register for the webinar. After completing the registration, you will be directed to a page with the webinar URL and option to save to your calendar.
  • First-time zoom webinar/meeting viewers can visit the following page to test access to the webcast system.

March 14, 2017, 1 pm - The USDA Natural Resources Conservation Service - Science and Technology will be hosting a webinar, Soil Health Economics: A Farmer’s Perspective. More information about the webinar and how to participate can be found here.

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

Rachel Kennedy
(515) 294-6685

Melissa McEnany
(515) 294-9075


Iowa Manure Management Action Group
Twitter: @iowamanure

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