AMES, Iowa ? When a corn plant is stunted, or not growing normally, nitrates can build up in
the plant. Typically, nitrogen that is taken up by the corn plant is converted to amino acids ?
the building blocks of protein ? but in the stressed plant this conversion does not occur. And
that's why producers need to know how to handle and feed drought-damaged corn in silage form,
according to Steve Ensley, of Iowa State University's Veterinary Diagnostic and Production
Animal Medicine (VDPAM) department.

"The nitrate level can be high enough in stunted plants that if harvested as silage the nitrate can
be toxic to livestock that consume the silage," Ensley said. "The most common problem is when
drought stressed corn is green chopped and fed to livestock without going through ensiling."

Ensiling will lower the amount of nitrate in the plant. Nitrogen availability to the plant, which
will depend on recent rain, fertilizer applied and other factors, will affect the level of nitrate in
the plant. If producers are planning on making silage from drought damaged corn, the only way
they can be sure about the level of nitrate is do some sampling and testing of the corn silage
before feeding.

"Producers have several options to help determine whether nitrate toxicity might be a problem,"
Ensley said. "Assess the corn field that will be harvested to determine how much of the field
has stunted corn that's not developing a normal ear. Take samples either by taking grab samples
of silage cut by a forage chopper or by cutting several entire plants by hand that represent the
various types of corn in the field."

A quick test that will screen for the presence of nitrates in stalks without having to chop the
stalk can be done by ISU Extension beef and dairy specialists. A drop of diphenylamine in
sulfuric acid on the surface of a stalk split in two will turn a blue-black color if nitrate is present.
However, this does not provide a concentration of nitrate. Availability of this screening test
varies. In some cases, the screening test may be a part of drought meetings where the beef or
dairy field specialists are present.

Other options include getting a representative sample of several stalks and performing a
strip test, which can help determine the concentration of nitrate by sending in a sample. ISU
Extension beef and dairy specialists also will have capability for this, but due to the time
required to prepare the sample for analysis the availability will be more limited than the
screening test. Samples also can be sent to commercial feed analysis labs, or your veterinarian
can send samples to the Iowa State veterinary diagnostic lab.

For more information on nitrate toxicity in drought damage corn silage, see the fact
sheet "Nitrate Toxicity" on the Iowa Beef Center website. Producers also can contact their ISU
Extension beef specialist or dairy specialist. Additional drought-related information is available
on the Extension and Outreach Dealing with Drought website and the Iowa Beef Center website.

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As the drought continues, cattlemen need to look at numerous management practices to help stretch their feed supply and maintain performance and reproduction in the cow herd. Here are a few strategies that may help.

First, develop a plan before the drought conditions get any worse. How do you plan to provide emergency feed in the short-term, as well as winter feed in the longer term? This requires an inventory of feed currently available and an inventory of the cow herd. You can often purchase hay less expensively during the growing season than in the winter. You also have the option now to incorporate silage into your winter feed supply.

Second, give your pasture some rest. Consider splitting your pasture into smaller paddocks and sacrificing one to use with supplemental feed. Allowing the other paddocks to rest and regrow when rain occurs this fall will probably result in more fall forage available to the cow herd. Also rotational grazing reduces selectivity in a cow's grazing habit, enhances forage utilization rate, and can improve pasture carrying capacity by 10 to 30%.

Consider weaning calves early. This will reduce the demand on the pasture forage by 25-35% and will reduce the nutritional demands of the cow by 30-40%. Creep feeding calves can help reduce the demand on the pasture slightly and will help prepare the young calf for weaning.

Cull all free-loader cows. Any late-calving cows, open cows, cows with feet, leg, and eye or udder problems should be sold immediately. Why waste precious feed on cows that don't perform?

Finally, get your winter feeds lined up soon. Whether you need to locate a custom chopper or bagger to chop your silage, or you need to lay out fence for grazing standing corn, it is much easier to do now that at the last minute.

More information on cow management strategies during a drought, or forage planning, can be found on the Iowa Beef Center web site at www.iowabeefcenter.org/droughtresources.html or by calling the Benton County Extension office at 319-472-4739, or Denise Schwab, ISU Extension Beef Program Specialist, at 319-721-9624.

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Master Gardeners are volunteers, trained by Iowa State University (ISU) in horticulture, who return service to the community through educational projects. What really sets them apart from other home gardeners is their commitment to learning and sharing what they learn with others. Each year ISU Scott County Extension & Outreach extends this opportunity to 25 residents of
Scott County.
 
Master Gardener trainees attend over 50 hours of scheduled classes and complete 40 hours of volunteer service during their first year to become Master Gardeners.

Classes will be held from 6:30 to 9:30 p.m. on Tuesdays and Thursdays starting September 6th and ending October 30th. There is a fee of $150.00 which covers your training and materials provided by ISU Scott County Extension & Outreach.

If you are interested in becoming an Iowa Master Gardener, contact the ISU Scott County Extension & Outreach Office, 875 Tanglefoot Lane, Bettendorf (359-7577) for an application form for this fall's training session. The application may also be accessed from our website http://www.extension.iastate.edu/scott/ .