Tuesday, May 24, 2016

Recovering from Cold Temperatures and Frost

Abnormally cold temperatures and frost created significant injury in most corn and some soybeans.  Many soybeans were planted late enough that they had yet to emerge by the time of the cold temperatures and frost on 5/14/16 and 4/15/16.  By and large soybeans were spared from the frost, that said, several thousand acres of early planted soybeans will be replanted in Southeastern Minnesota.

Corn injury and recovery appears to be influenced by planting date.  Reports from the earliest planted corn (4-10-16 to 4-12-16) are that injury was not too significant and that they have recovered well.  I have not validated these claims with any of my own observations.

The second corn planting date, around April 19th, sustained serious damage and has had the most difficult recovery.  My infield observations are that stands have not been reduced by much, if at all, by the frost. That said, the crop has come back unevenly and upwards of 20,000 of plants per acre remain buggy-whipped or tied up as of Monday May 23rd (stand counts remain at 34,000 to 35,000).  Plants from this planting date exhibit a wide range of symptoms that vary by field and within fields.


Damaged Recovering Normally

Damaged Recovering Buggy-whipped

Damaged Recovering Buggy-whipped

Damaged Recovering Buggy-whipped

Damaged Recovered Leaning


Corn planted in the 3rd planting date around the 26th of April appeared to have sustained the most significant damage initially, but they are recovering better than the second planting date.  Generally this corn looks better and has fewer buggy-whipped plants.  Generally there are 3,000-8,000 plants per acre that are buggy-whipped.  Attempts to "unfurl or untie" plants by clipping have very mixed results and have the potential to cause negative results.  A good overview on this topic can be found here: http://cropwatch.unl.edu/2016/risk-freeze-damage-early-planted-corn

Finally, corn planted the first part of may was not affected by the frost.  It is one or two stages behind early planted corn, but looks nice and healthy.


 We will update as the season continues.  We would appreciate learning about what you are experiencing, so don't hesitate to contact us or post a comment below.

Ryan Miller

Friday, May 13, 2016

Watch for Giant Ragweed Emerging in Early Planted Soybeans

May 13, 2016

Southeastern Minnesota has been busy planting corn and soybeans over the past 4 weeks.  Much of the corn was in before the end of April and several fields of soybeans were planted before the calendar was changed to May as well.  Once May came, there were many good planting days, so much of the soybean crop is now in the ground, too.  It is great to have the crop in the field, isn't it.  For a number of folks, there were also windows of opportunity to apply preemergence herbicides on both crops.

Applied or not, the next job on the list is to watch the emergence of your crop and weeds.  An early planting favors giant ragweed, one of our first troublesome weeds out of the ground.  We already have seedling giant ragweed in our corn herbicide trials (planted April 25).  The plots with no preemergence herbicides or ones with herbicides weak on giant ragweed have a nice carpet of seedlings in them.  The message, this weed grows quickly and can pass the 2-3 inch mark very quickly.  Once past the 2-3 inch mark, it becomes more challenging to control, especially if it is herbicide resistant. There are several good options for post emergence control in corn, but not so in soybeans.

If you are dealing with glyphosate resistant giant ragweed in RR soybean, you need to target them at 2 inches with a SOA-2 or SOA-14 herbicide.  Examples include FirstRate, Flexstar GT, or Cobra.  If you also have SOA-2 resistant giant ragweed, the FirstRate will not work for you.  If you planted LibertyLink soybean and did not get a preemergence herbicide on, you need to target the first glufosinate (Liberty) application when the ragweed is small and include a residual that will help with the giant ragweed and other weeds.  See results from our 2015 herbicide trial near Rochester on SOA-2 and SOA-9 resistant giant ragweed for more details. 
Weed Control Programs for SOA-2 & SOA-9 Resistant Giant Ragweed

To view more herbicide trial results in corn and soybeans check out our complete report at:
2015 Southern Minnesota Crops Research Report

Seedling giant ragweed

Lisa Behnken, Extension Educator, Crops (lbehnken@umn.edu)  

Tuesday, May 3, 2016

Manure and nitrates in United States courts

Most people are aware of the lawsuit currently going on between the Des Moines Water Works utility and three county drainage districts upstream of its water supply over nitrates in in Des Moines drinking water.  A lesser known case, but equally important for agriculture, is the one decided against Cow Palace LLC, a dairy farm, by the Eastern District Court of Washington State.  There is a well-written article by several Minnesota lawyers and economists here that discusses the implications of these two cases.  Take a look.

My understanding of the law is about on par with my understanding of astrophysics, so a lot of the “legalese” is above my head.  But a few lines really stood out to me that relate to the Cow Palace/Dairy Farm case, manure application, and environmental risk.

“The RCRA agricultural-waste exemption was limited by the court, which held that manure is to be regulated as a solid waste similar to garbage if it is ‘handled and used in a manner that its usefulness as a fertilizer is eliminated’…In the Dairy Farm case, the court essentially shifted the burden to the farm or livestock operation to show that manure is only being applied to land as a beneficial fertilizer to be used by crops in the root zone.”

A little background on the Cow Palace/Dairy Farm case: a dairy farm operator in Washington State was sued by two community groups that claimed the farm was violating the Resource Conservation and Recovery Act (RCRA), which prohibits the disposal of solid waste to the land.  Manure is generally considered exempt from this law because it’s used as a fertilizer source on the land.  However, what the court did by ruling in favor of the community groups was suggest there are limits to that exemption, and that those limits relate to whether the manure application was intended to fertilize crops or to dispose of manure.

Here are my thoughts on what this court case means for farmers:     

1. It’s putting the burden on farmers to show they’re applying nutrients in manure at agronomic rates- no more than what the crop will be taking up.  Cow Palace/Dairy Farm got in trouble because they were applying manure to empty out the lagoon, not to apply to cropland at agronomic rates.

2. It’s really important to keep records of manure applications and manure analysis results so you can demonstrate you were applying at agronomic rates.

3. It points out the legal importance of following good manure management practices.  Practices have to be defensible, and the best way to do this is by following University research-based guidelines and replicated on-farm research.  University of Minnesota publications and fact sheets regarding manure application can be found here.

Thursday, April 28, 2016

EPA Extends Comment Period on Proposed Decision to Register Dicamba for Use on Genetically-Engineered Crops

The EPA has extended the comment period on the proposed decision to register dicamba for use on genetically-engineered crops until May 31, 2016.  With a decision expected in late summer or early fall 2016. Ultimately this means we won't see dicamba available for us in genetically-engineered  crops this summer.  A full accounting of the situation can be found by clicking here.

If you wish to make comments on the proposed decision click here.  To learn about making effective comments you may wish to read this document. Remember your input is invaluable in the decision making process. 

Dicamba tolerant soybeans are available to plant in Minnesota, but at the current time dicamba tolerant soybeans have not been approved for import into the European Union.  The Minnesota Soybean Grower Association wrote an interesting article addressing this situation found here.

Remember if you make the decision to plant dicamba tolerant soybeans, at the current time it is illegal to apply any form of dicamba to them, and it is likely to be illegal for the whole 2016 growing season given the proposed EPA timeline.


Monday, April 25, 2016

Fahrenheit 50: Fall weather and nitrogen loss

I arrived in Minnesota during a December that was extremely wet and extremely warm (at least by Minnesota standards).  Being accustomed to more southern climates, it made me feel right at home, but I have to say- it isn’t very good for water quality, and it isn’t good for farmers.  Especially if you applied manure last fall here in southeastern Minnesota.

The microorganisms that are responsible for nitrification, the process that converts ammonia or ammonium nitrogen into the nitrate form are more active at higher temperatures.  While most nitrogen in manure is in organic forms, much of the organic nitrogen will convert to ammonia, and then to nitrate by the nitrification process.  Nitrification slows to a crawl when soil temperatures fall below 50° F.  This year that did not happen until mid-November in southeastern Minnesota; in an average year it would be closer to mid-October.  That difference can be critical because most of the rains we get that leach down through the soil into groundwater happen in late fall and in the spring, and nitrate is the only persistent form of nitrogen that moves easily with water.  So, if the soil temperatures stay warm for a while after manure application, nitrogen can be rapidly nitrified and lost from the soil when there isn’t a living crop there to use the nitrogen. 

Think about it this way: if you apply manure in the fall when soil temperatures are still fairly warm, a decent amount of the urea and ammonia in that manure could convert to nitrate before the soils freeze up, and then that nitrate could get leached below the rooting zone with spring rains.  That same manure applied after the soil cools below 50° F would not form much nitrate before the soils froze.  In the spring, it would take two or three weeks of warm soil temperatures before the urea and ammonia in that manure would convert to nitrate, and so any rain coming in the intervening time would not be leaching the nitrogen down through the soil- you have a lower risk of nitrogen loss.  Small differences in timing your manure applications can lead to big differences in how much nitrogen sticks around for your crop.

Weather conditions from fall 2015 to spring 2016 have definitely made a good case for using nitrification inhibitors, which slow the conversion of ammonia or ammonium nitrogen forms into nitrate.  Nitrification inhibitors lessen nitrate losses and improve yields in many years, especially those that are warmer and wetter during the late fall through spring.  I think it’s a no-brainer with fall-applied manure.

So, if you applied fall manure this year, particularly before mid-November or late October without a nitrification inhibitor, it’s probably worth asking how much of the nitrogen you applied is still around for your crop this spring.  Fortunately, there is a well-validated spring soil nitrate test that can help you answer that question- U of M extension has a good publication on it here.  I would highly recommend it if you are relying on fall-applied manure as a part of, or all of, your nitrogen fertilizer source.  Feel free to contact me if you have questions or comments.

Note: I talked about nitrogen from manure here, but the same challenges occur with fall-applied nitrogen fertilizer.  Because of the high potential for leaching losses, fertilizing in the fall is not recommended in southeastern Minnesota.  More information can be found in the Nitrogen Best Management Practices publication found here.