News release: Drought-Stressed Corn and Nitrates

Tim Baker, MU Extension Horticulture Specialist
102 N. Main, Suite 1, Gallatin, MO 64640

Release Date: August 2, 2018
Headline: Drought-Stressed Corn and Nitrates

Most of the northwest quarter of Missouri was already abnormally dry or in actual drought starting in January and continuing through all of 2018 thus far. It affects agriculture, our water supply, fire concerns, and even recreation and tourism.

I will be addressing some of the issues that we face with this year’s drought over my next few columns. Believe me, it would be fantastic to abandon my plans for future columns on the drought because we start getting lots of rain… but for now, it’s not in the forecast. And for many crops, it’s too late to do any good even if we do see some rain.

For this week, I would like to concentrate on an immediate concern of many farmers who are wondering if it is safe to feed their corn to livestock.

The problem is, of course, the nitrate content of their corn. We had this same problem back in 2012, and there were reports back then of livestock being poisoned from high levels of nitrates in their corn.

The situation was on our MU Extension “Radar Screen” earlier this year. As in 2012, we ordered nitrate test kits, and some farmers are bringing corn to Extension Centers for us to test. The type of test that we use does not give nitrate quantities in corn, but simply shows if there is cause for concern or not.

If you would like to have your corn tested, please contact your local Extension Center, to make sure that nitrate testing is offered in that office.  It’s also a good idea to make an appointment, to be sure a specialist will be there who can conduct the test.

Many growers who have been through this before know that putting corn into silage may help. The fermentation process may reduce nitrate levels up to 50% or so, but there are no guarantees. The success depends on if it is good corn silage…correct moisture, good packing, etc.

After the process of ensiling the corn is completed, it’s best to send samples to a lab to get some numbers back on the actual nitrate content of your silage. Then call one of our Extension Livestock Specialists to discuss the results. You may be able to use the silage as is, or it may need to be combined with other feed sources to reduce the amount of nitrates that your livestock are eating. Our Livestock Specialists can determine the best ratio to use.

I have seen varying results on nitrate tests here at the Daviess County Extension Center. Corn which is severely drought-stressed has very high nitrate levels. Some corn, from fields that have been getting timely rains, does not show significant nitrate levels.  Keep in mind, though, that nitrate levels can vary from plant to plant. It’s best to bring in several typical specimens for us to test.

In future columns, I will be looking at the actual rainfall and evapotranspiration data that I have recorded here in Gallatin. I will also be comparing this year’s drought with 2012 in several ways, plus posting photos. This is an ongoing process, and you can see what I have so far on my web site:  In addition, I have links to other drought-related resources.