Spreading Manure, Spreading Herbicide Resistant Weeds?

I have decided this month to discuss a subject that has been coming up more frequently in conversations the past few months.  Herbicide resistant weeds have been a growing problem for many years.  And the majority of the farmers have been doing what is known to be the best cultural practices to keep the resistance to a minimum.  A rotation of herbicides, cleaning off equipment, tillage, and crop rotation all have helped when we are not growing continuous corn.
Two years ago I started to notice some non-native weeds in fields that had been spread with chicken and turkey litter from Arkansas.  At that time I was more concerned with a buildup of arsenic previously allowed for internal parasites accumulating in the soil structure.  The conversation acknowledged that these weeds were hard to kill and deserved close monitoring.
I remember growing up that there were thoughts that the weed seed that went to the elevator might be returning to the farm under the guise of protein in livestock feed.  Many of us noticed that we seemed to have higher concentrations of weeds where we had spread manure.  At that time row cultivators were still in common use and we didn’t find any weeds that were resistant to the “iron” that cut them off.
Northwest Indiana and many other areas are currently dealing with resistant Palmer Amaranth that some believe may be hidden in with the cotton seed hulls or meal that is fed to the livestock.  Many of the smaller weed seeds may not all get pulverized during the feed processing procedure.  Some of these weed seeds are in the homegrown grains we feed our own livestock.  As some of these seeds make the journey intact through the digestive system they are introduced into new crop fields or re-introduced back onto the fields where they grew previously.
I am not pointing fingers at feeders, feed manufacturers, or those need to apply manure either on their own ground or to accept it from an outside source.  The reason I chose this article for today is to cause us to pause and investigate what our part might be in slowing the spread of these problem weeds.  Our current influx of cover crops need to be checked for contamination also.
With increasing input costs and commodity prices off last year’s highs, let’s get back to having all phases of agriculture being profitable.  I have friends raising grain, selling feed, feeding livestock, custom spreading manure, and trying to control the weeds from the fertilizer plants.  We can make progress if we share information and make good decisions. 
Thanks for your time and I hope this as a discussion starter.

Brad Forkner, Owner
Nutrient Management Specialists, LLC
Home of Solid-Solutions for Livestock
P.O.Box 303
614 E Cherry Ave.
Cherry, IL 61317
815-257-8463
brad@nutrientmanagementspecialists.com
http://www.nutrientmanagementspecialists.com/
Skype: brad.forkner1
Twitter: @BradForkner