Manure Management

October - December 2002

Joel DeJong , crops field specialist
Kris Kohl , agricultural engineer field specialist


Managing manure in an economically and environmentally sustainable manner is a concern for many Iowans. Concerns have existed that over application was occurring and at the same time, producers worried that under application would cost a significant yield loss. The need to better understand the value of crop nutrient content in manure and matching that better to crop use is critical for NW Iowa because a lot of livestock is produced here, and Iowa laws were mandating management changes.


Funds were obtained from the Leopold Center to research the attitudes of Sioux County residents regarding manure use and identify present practices. During the time when the application of this grant was being considered, we had kicked off this project by doing a field trial where manure, no manure and commercial fertilizer was applied to a corn field to observe how nutrients from manure can be available for the crop. A field day held in conjunction with that demonstration had 10 farmers attending. After the project started, we did another similar plot in a different location in Sioux County . Fifteen attended this field day. Yield information from both plots, showing that manure can be a pretty reliable crop nutrient supplier if managed carefully, was shared in many formats.

As we started to get results from the project, we wanted to share that information with those who were participants in the survey conducted that was used to assess present practices and attitudes. So, we developed a newsletter and sent this to the people listed as "operators" on the Farm Services Agency list, which is over 1000 people. This newsletter had two issues, May 2000 and August 2001.


The findings of this study have been used in many educational presentations in NW Iowa and around the state. The last project survey showed that 80 Sioux County producers (29% of survey respondents who used livestock manure) have made changes in manure management because of this project and many more in other counties have as well.
51% had tested their manure previously, now over 55% have tested it. Our survey also showed that the confidence level for reducing commercial fertilizer applications goes up rapidly if manure nutrient content testing has been done. Data on calibration has gotten more producers looking closer at doing the little things right - like calibrating - to make sure they can get full use out of manure nutrients. 57 producers said they have or will calibrate if given the opportunity to have access to equipment for calibration, 156 more said they might.

Other items from the pre- and post-project surveys of interest include that now more than 87% of the respondents reduce their use of commercial fertilizer on acres that have manure by at least 50% - with 60% of commercial P and K applications reduced to zero, and about a third of N applications reduced to zero. All of these categories showed significant improvement from the pre-project survey. In order for livestock producers to feel comfortable with making changes, they have to see information that is logical to them, and that helps them understand progress can be made. This project has put more of that useful information in their hands - so they can make those management changes - and many have!


Page last updated: July 10, 2006
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