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Rick Snell's Ag Roundup
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In spite of the fact that my thermometer next to the house only read 37 degrees, I had several farmers tell me that in early October, there was a light frost. It wasn’t a killing frost, as everything is still green at my place. But, it did burn the tips of some vegetation out in the countryside. Anyway, ever since that chilly morning, I have had a number of phone calls relating to nitrates and prussic acid.
We have had extremely dry conditions the last 50 days here and throughout a big part of the state. Thus, the conditions for high nitrate levels in forages have been right. I am a believer in testing for both nitrates and prussic acid although I think you can manage easier for prussic acid than you can for a nitrate problem.
A few years ago, I had a producer in northern Barton County that had some cattle die during the winter and come to find out from the autopsy, they had nitrate poisoning. He had run a quick test on some of the feed in the fall and it all checked alright. So, he retested after they died and found out that only two bales or so out of several hundred were “hot”. This makes sense when you consider that you can look over a field of sudan or forage sorghum and see stunted, drought stressed areas.
Does this mean we should throw forage testing out the window? No, I still think it is a good guideline but it is not an exact science and it’s not fool-proof. One reason it isn’t perfect is that the test is no better than the sample. This is why you might want to test potentially “hot” areas separate or at least make sure they are included in the sample.
As far as frost goes, it can be a factor but I think other things are bigger factors. Never the less, we often say to wait a week or even 10 days after a frost before grazing cattle or cutting the hay.
Let me just hit on two or three things that will limit your problems. First, on prussic acid, it is only a grazing problem. As soon as you cut it for hay or silage it is all but eliminated, if allowed to cure properly. Green chop can be a problem if fed immediately. Most importantly though, if you will just wait until all of the forage gets up to about 18” tall, it should be fine. It is usually the rapidly growing, short plants that are often re-growth that have prussic acid concentrations.
The biggest culprits on prussic acid are johnson grass anytime and milo or forage sorghum afer it has been harvested. After harvest you will often get regrowth. Johnson grass produces suckers or tillers all the time.
In terms of nitrates, the biggest thing is to raise the cutter bar up to a height of 6”-8” off the ground. Most of the nitrate is in the lower part of the stalk. There is seldom much in the leaves or the grain. When grazing, cattle are seldom going to eat the lower part of the stalk unless there is nothing else out there.
If you do have high nitrate forage, one thing you can do is blend it with feed that is low in nitrate.
Another thing to check is your livestock water source. Water with high nitrate level compounds the problem. 
A number of crops, weeds and forages can accumulate nitrate. These include not only the sorghum - sudan family of plants but also pigweeds and kochia. Oats and dryland corn can also be a problem. Hybrid pearl millet is notorious for being high in nitrates.    
For more information, you can pick up a copy of the K-State extension publication, “Nitrate and Prussic Acid Toxicity in Forage”, or we can mail it. It is free for the asking and is also available on the K-State website.
At least one farmer and one banker from our area have attended the intensive short course in agricultural economics called MAST. It is offered by K-State and they both rated it highly. This years program is coming up soon as is the sign-up deadline.
Farmers and ranchers seeking ways to enhance management, decision-making and strategic planning skills are encouraged to enroll in the Management, Analysis and Strategic Thinking (MAST) program. The program, hosted by Kansas State University’s Department of Agricultural Economics, kicks off with a two-day, on-campus session Nov. 16-17. The enrollment deadline is Oct. 29.
MAST includes two on-campus sessions and online learning modules addressing topics such as land, machinery, financial analysis, human resources, tax and policy, risk management and marketing. The program concludes with a second on-campus visit Feb. 22-23, 2011.
Past participants include producers from across the United States representing diverse agricultural backgrounds, from cow-calf producers and diversified crop farmers to land owners and dairy managers.
Tuition costs $1,250 per person or $1,100 per person if two or more participate from the same business. More information is available on the MAST Web site: or by contacting Shannon Krueger at 785-532-6994 or
Farm Credit Associations of Kansas are offering partial scholarships for their members.
The Water and Future of Kansas Conference will be held in Topeka on October 26. Call 785-532-5575 for more information.... The first Kansas Income Tax Institute will be held in Topeka, October 28-29.... Fort Hays State University will offer their Annual Agricultural Outlook Conference on October 29 at the Student Union.... The Kansas Green House Growers Educational Conference is October 28 in Manhattan....  A crop insurance workshop will be held in Salina on November 4.
Rick Snell is the Barton County Extension Agricultural Agent for K-State Research & Extension. He can be reached at 620-793-1910 or The Barton County Extension Office is located at 1800 12th Street in Great Bend.