Corn Stalk Nitrate Risk

It is crazy to see harvest underway and corn fields being picked in areas already! With the lack of forage for livestock and some dry land crops burnt, I’ve been receiving several questions about nitrates in corn stalks for grazing. Bruce Anderson, UNL Forage Specialist recently wrote an article on the nitrate risk when grazing corn stalks which I’ve inserted below.

Anderson poses the following questions: Will drought-stressed corn stalks have high nitrates?  Probably.  Are they dangerous to graze?  Maybe.  Should you use them?  Don’t know because nitrates are unpredictable.  There are however certain characteristics about nitrates in corn stalks and grazing animals that can be used to develop better answers to these important questions. For starters, testing for nitrates is absolutely essential for making wise decisions and you need to sample the right plant material for testing to get useful information.

What is the right material?  Begin by looking for the most dangerous situations such as patches of dryland corn less than three feet tall which cows will seek out and graze right to the ground.  Sample the whole plant.  If nitrates are dangerously high, consider fencing it out.  For taller, heavier plants where cows are unlikely to eat the bottom stalk unless forced, test the whole plant except for that part of the stalk the cows won’t eat.  Maybe sample plants in areas that received both manure and nitrogen fertilizer.  Bruce also reminds producers to not forget about the weeds. Pigweed, lambsquarter, kochia, nightshade, and other weeds can be toxic.

Finally, Anderson reminds us that nitrates in drinking water can make the situation worse so check your those levels and be extra cautious using protein supplements based on non-protein nitrogen sources like urea. Be extra careful grazing corn stalks this year to keep your animals safe.

Soybean Pest Updates

Several years ago I was called to a Thayer county field where I found soybean stem borer present. Then I sampled several fields in Fillmore County and found them as well. Now is the time to be cognizant of this if you notice dead leaves and lodging. There are no control measures at this time, but monitoring your fields and being aware of fields with large populations will help minimize losses due to lodging by harvesting those fields first.

Two of my colleagues, Loren Giesler and John Wilson have recently pointed out that “this year’s drought conditions may hold one benefit for soybean producers: a better opportunity than most years to scout for the elusive soybean cyst nematode (SCN).” They go on to say that damage due to soybean cyst nematode typically does not show any above ground symptoms, especially with normal conditions for soybean production. In years with stressful conditions, especially drought stress, symptoms will be more evident.

Patches of stunted, yellow, and/or wilted soybeans could indicate the presence of SCN. The nematode population will vary across the field and will be found in dense pockets. You may see patches of soybeans that are more affected with gradients of damage extending out from a center area which corresponds to these pockets of higher soybean cyst nematode. This will look much like a low spot in the field that has a root rot problem.

If you see these symptoms and have not tested for SCN in your fields, consider collecting soil from these sites. The Nebraska Soybean Board funds a free sample program
. Send in your soil sample to receive have it tested and determine the egg density in your field. Sample bags are available at the extension office or by calling (402) 472-2559.

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