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Herbicide Grazing Restrictions

Forage Feed Grazing Restrictionscattle in corn stalks

Replant Options Rotation Restrictions-long

Grateful for a nice week for harvesting and for the good yields being reported!  It’s also good to see cattle being turned into cornstalks.  A reminder to read herbicide labels to understand if there’s any grazing restrictions from corn and soybean herbicides applied in-season.

It’s also important to look for any grazing restrictions on fall-applied herbicides to control marestail and other germinating weeds.  These restrictions can also be found in the Forage Feed Grazing Restrictions in the UNL Guide for Weed Management.  The forage, feed, and grazing restriction only applies to the crop for which the herbicide was applied.  When it comes to grazing cover crops planted into these residues, one must use the replant/rotation restriction guidelines found on the herbicide label and in the UNL Weed Guide: Replant Options Rotation Restrictions-long.  I apologize as these scanned blurry; hopefully you can zoom in ok to read what you need.

If the label doesn’t specify any restrictions, then it should be ok. If you want to be on the safe side, a rule of thumb is to use the pre-harvest interval for the amount of time to wait before grazing stalks.  Some labels will say that residue should not be grazed or baled and fed to livestock.  Sometimes studies were actually conducted to know there is a safety concern.  In other cases, the chemical company may not choose to conduct all the studies the Environmental Protection Agency (EPA) required for labeling due to high costs.  If that’s the case, the EPA requires the strongest restrictive language be placed on the label. Regardless, if it says there’s a grazing restriction on the label, the label needs to be followed as it is a legal document and the law.

As you plan for next year’s herbicide program, if you’re thinking about fall cover crops, the following NebGuide may be of benefit to you as it goes through the grazing restrictions of various herbicides.

UNL Grazing Corn Residue Research

Many stalks in Nebraska are left ungrazed for various reasons.  One reason I’ve heard is the potential impact of increased compaction and reduced yield of the next crop.  Nebraska Extension has long-term research addressing this concern…in fact, 16 years of research conducted at the Ag Research and Development Center near Mead.  There’s various components to this study and you can view the full report at: http://go.unl.edu/8mp6.

In this study, cattle were allowed to graze corn residue in the spring (February to mid-April) or the fall (November through January) and these treatments were compared to an area not grazed.  Corn and soybeans were planted the spring after grazing the residue for 16 years to determine the effect of grazing on the subsequent crop yield.

In the fall grazing treatments, the corn and soybeans were planted no-till.  For corn or soybeans planted into the spring grazing treatments, three tillage treatments were also implemented for nine years:  no-till, ridge-till, and spring conventional till, after which all treatments were converted to no-till.  This result of the tillage by spring grazing treatments for either corn or soybean yield over nine years showed no interaction and suggested the same effect on yield regardless of tillage treatment used after spring grazing.

Table1-Beef

Effect of Corn Residue Removal on Subsequent Crop Yields“, 2015 Nebraska Beef Cattle Report. Mary E. Drewnoski, L. Aaron Stalker, Jim C. MacDonald, Galen E. Erickson, Kathy J. Hanford, Terry J. Klopfenstein

Spring grazing across all tillage treatments did increase soybean yields statistically (58.5 bu/ac for spring grazed vs. 57.0 bu/ac for ungrazed) and had no effect on corn yields.  The results were similar looking at 16 years of grazing vs. not grazing under no-till for both corn and soybeans in the spring; there was no yield effect found for corn and the soybeans showed a slight yield increase with grazing.

Table2-Beef

Effect of Corn Residue Removal on Subsequent Crop Yields“, 2015 Nebraska Beef Cattle Report. Mary E. Drewnoski, L. Aaron Stalker, Jim C. MacDonald, Galen E. Erickson, Kathy J. Hanford, Terry J. Klopfenstein

Looking at a 10 year period of no-till management for both spring and fall grazed corn residue and subsequent corn and soybean crops, fall grazing statistically improved soybean yields over both spring grazing and no grazing (65.5 bu/ac vs. 63.5 bu/ac and 62.1 bu/ac respectively).  No grazing effects were observed on corn yields in either season.  All statistics were at the 95% confidence level meaning the researchers were 95% confident any yield differences were due to the treatments themselves vs. random chance.

Regarding compaction, in the fall, the field was typically frozen and the researchers felt any mud and compaction associated with grazing cattle was minimized; highest subsequent soybean yields were achieved with fall grazing.  The spring treatment was designed to look more at potential compaction and muddy conditions after spring thaw till right before planting-thus the implementation of different tillage treatments as well.  They used a stocking rate consistent with UNL grazing recommendations resulting in removal of half the husks and leaves produced (8 lbs of leaf and husk per bushel of corn grain produced).  Results of this study indicate that even with muddy conditions in the spring, grazing increased subsequent soybean yields compared to not grazing regardless of tillage system used and that corn yields were not different between grazing vs. not grazing and regardless of tillage system used in the spring.  This study was conducted in Eastern Nebraska in a rainfed environment with yields ranging from 186-253 bu/ac with a 16 year median yield of 203 bu/ac.

Additional Grazing Study

A five year fall grazing study (December through January) was conducted in an irrigated continuous no-till corn field at Brule, NE to determine the effect of corn residue removal via baling corn residue or fall grazing on subsequent corn yields.  That environment receives limited rainfall and residue is deemed important for reducing evaporation of soil moisture in addition for catching/keeping snow on fields.  Farmers were questioning the effects of any residue removal on subsequent corn yields and the study was implemented.

Treatments were 1) fall grazing at 1 animal unit month/acre (AUM), 2) fall grazing 2 AUM/ac, 3) baled, or 4) ungrazed.  The researchers found that residue removal did not affect corn grain yields from 2009-2013 in the continuous corn rotation.  There were no statistical yield differences with 5 year average yields of:  152 bu/ac, 155 bu/ac, 147 bu/ac and 148 bu/ac respectively for the above-mentioned treatments.

Table3-Beef

Effect of Corn Residue Removal on Subsequent Crop Yields“, 2015 Nebraska Beef Cattle Report. Mary E. Drewnoski, L. Aaron Stalker, Jim C. MacDonald, Galen E. Erickson, Kathy J. Hanford, Terry J. Klopfenstein

Drought Dichotomy

We often say water is the lifeblood of agriculture.  In a drought year like this, that truly is the case!  A case study showing the impacts of irrigated agriculture to Nebraska this year can be found here.

Interesting is the dichotomy we’re experiencing in south central Nebraska where irrigated fields that were truly fully irrigated may have some of the best yields producers have experienced while in so many areas of the State-even neighbors a few miles away-are experiencing the worst year they have ever faced.

Dryland yields have been all over the board mostly depending on tillage type.  Irrigated yields that were truly fully irrigated have been outstanding.  Hybrid Maize predictions for our area had been good all year for fully irrigated corn and it looks like they are even better than the long-term average predictions!

Yet, as I drive around the countryside I can’t help but wonder at how many corn stalks are already being disked under.  At a time when we’ve had several fires in our own State of Nebraska…when we have farmers and ranchers suffering trying to find forage for their livestock.  We are so blessed to have irrigation here and that buffers our producers from weather extremes.  But let’s not forget about the others who are hurting right now!  I would ask our producers with irrigated fields to please consider leasing your stalks for grazing or baling them this year to help those in need of forage.

Research from UNL shows that cattle and cornstalks go well together.

Some producers worry about compaction but in a dry year like this, compaction is essentially a non-issue-at least this fall.  UNL research from 1996-2011 showed the effects of fall and spring-grazing on subsequent corn and soybean yields.  On average,  yield of the following soybean crop was increased by about 2 bu/ac with fall-winter grazing, and 1.3 bu/ac with spring grazing, compared with no grazing of corn stalks.  Yield of corn as the second crop after grazing was not significantly affected resulting in an average of 1-3 bu/ac yield increase depending on fall or spring grazing. Check out this study and all our resources to help with drought decisions.

An upcoming Webinar called Cornstalk Grazing-Understanding the Values to Cattle Producers and Corn Farmers scheduled for  Oct. 2 from 12:30 to 1:10 p.m. will provide additional information.  If you are unable to view it, it will be recorded with all our Beef Webinars.

So while irrigation has provided life and good yields to many producers’ crops in the area, let’s not forget about our neighbors who are less fortunate.  Please consider leasing your corn stalks or baling them to help others in need of forage for their livestock!  You can connect with other producers by checking out the Hay and Forage Hotline at 800-422-6692.  This hotline lists hay and forage including cornstalks that is available via sale or donation.

Additional Resource:  How much to charge for cornstalk grazing?

Fall herbicides & Grazing Corn Stalks

With the increasing problem of controlling weeds such as marestail (horseweed), UNL has recommended using fall applied herbicides to help control this in addition to winter annual weeds.  This practice usually does help with weed control, but I hadn’t thought about the considerations when grazing corn stalks until I received a recent question on it.  The farmer wanted to see if it was safe for his cattle to graze corn stalks after a fall herbicide had been applied.  The label wasn’t clear so he gave me a call. 

I won’t provide information for the various herbicides that can be applied in the fall, but I will recommend that if you are planning on having your cattle graze stalks, that you check to see if a fall herbicide was applied and check the pesticide label to determine if there are any grazing restrictions with that pesticide. 

If the label doesn’t specify any restrictions, then it should be ok.  If you want to be on the safe side, a rule of thumb many chemical reps use is to use the pre-harvest interval for the amount of time to wait before grazing stalks.  Some labels will say that residue should not be grazed or baled and fed to livestock.  Sometimes studies were actually conducted to know there is a safety concern.  In other cases, the chemical company may not choose to conduct all the studies the EPA required for labeling due to high costs.  If that’s the case, the EPA requires the strongest restrictive language be placed on the label.  Regardless, if it says there’s a grazing restriction on the label, the label needs to be followed.  Your cattle may not be affected by grazing stalks where a chemical with a grazing restriction is on the label, but there may be other concerns such as problems with the chemical affecting the calf or being retained in the cow’s milk.

I’m still recommending utilizing our corn stalks by grazing and utilizing fall-applied herbicides for weed control.  I just also recommend you check the pesticide labels on fields where a fall herbicide has been applied to determine any grazing restrictions or safety concerns.

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