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 SPECIAL DROUGHT  INFORMATION- SUMMER 2002

Special Drought Information
 Editor's Note: The severity of the dry weather certainly differs from one county to another in our three counties (or from one township road to the next!), but it's safe to say that all farmers in the three county area are suffering some effects of this summer's drought. Attached in this special edition of Dollars and Sense is some information on how to manage livestock and crops (or lack thereof!) in this drought situation. As fall and winter approach we will obviously face additional challenges related to livestock nutrition and feeding, and of course, managing production costs. As always, please contact us if we can assist you with specific questions or concerns.

-Mike and Ken

Drought Website Provides Managment Information
Ohio farmers who have concerns regarding potential drought conditions that may affect crop and livestock performance can refer to an Ohio State University drought Web site for management information.

The Web site, created by Ohio State University Extension specialists, offers a wide variety of topics from drought news to weed control, to provide farmers timely and pertinent information on how to manage livestock and crop production during dry conditions.

"The site is a clearinghouse for drought information," said Peter Thomison, an Ohio State Extension agronomist, "where producers, crop consultants and the like can find what they may be looking for all in one place."

The Web site contains fact sheets, bulletins, and news releases on current drought news, livestock, corn, soybeans, forages, weed control, fruit production, and marketing information. It also contains a National Oceanic and Atmospheric Administration (NOAA) Drought Severity Index map and resource guide to other drought-related Web sites.

The site, which is updated on a regular basis, can be accessed by logging on to http://corn.osu.edu/droughto2/. The last time Ohio State posted a drought Web site was in 1999, when Ohio was faced with similar dry conditions.

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Drought-Stressed Corn for Silage
Much of Ohio is under drought conditions and producers are concerned about chopping corn for silage. Below are some answers to common questions.

Q. When should I chop corn for silage?

A. It depends! The most important factor affecting when to chop corn is its dry matter concentration. Corn chopped too wet ferments very poorly and feed intake is reduced greatly when it is fed. Corn chopped too dry ferments poorly, has low starch digestibility and spoils quickly during feed out. Corn should be chopped when its dry matter is between about 30 and 40% (equal to 60 to 70% moisture). Ideally the dry matter should be between 32% (for bunkers) and 38% (for upright silos). Do NOT chop corn for silage when its dry matter is less than 28%. Feed intake by cattle is usually much lower when fed very wet silage. Before a farmer starts to chop, he should go to the field and cut a few (3 or 4) stalks at the same height as he plans on setting the chopper. Cut the stalks into small pieces (about 1 inch) using a cleaver or heavy knife, mix the sample and then analyze the sample for dry matter using a Koster tester or microwave (see OSU Agronomy Fact Sheet AGF-004-90). If the corn has the correct dry matter, he can chop the field. If it is too wet, delay chopping.

Q. What about nitrates?

A. See Animal Science Fact Sheet AS-0003-90 attached for more details. Drought-stressed corn often accumulates nitrates. Nitrates are toxic to ruminants. This year all corn silage should be tested for nitrates before feeding. Nitrates are often not a problem during prolonged drought but can become very high when prolonged drought is followed by rain. After a rain, the soil nitrates move into the plant. Silage fermentation usually reduces the concentration of nitrates in silage. Fresh plants can have excessive nitrates but the resulting silage might be safe to feed. Therefore, knowing the concentration of the feed after fermentation is more important than knowing the concentration of nitrates in fresh corn plants. If nitrates are suspected, sampling fresh material can be useful however. Before chopping starts, sample a few plants from the field (cut at the same height as the chopper) and send in a sample. If values are low, you should have no problem. If values are high, chopping height should be increased because most of the nitrates are in the lower portion of the stalk. Guidelines for nitrate concentrations are below (make sure the lab values are in the same units).

<0.1% Nitrate-N (dry matter basis): Feed is safe

0.1 to 0.2% Nitrate-N (dry matter basis): Feed is probably safe, limit to no more than 50% of the diet for pregnant animals

0.2 to 0.35% Nitrate-N (dry matter basis): Do not feed to pregnant animals, limit to less than 50% of diet for other animals

>0.35% Nitrate-N (dry matter basis): High risk, should not be fed.

Q. Are there any human health concerns?

A. Yes. High nitrate corn when put into a silo produces large amounts of gases. These gases (mostly nitric oxides) can be lethal. If you see a yellow-orange gas cloud around a silo, keep humans and animals away from it.

Q. Are silage additives useful with drought-stressed corn?

A. To reduce nitrate concentrations, a rapid and active fermentation is needed during silage making. A good quality silage inoculant might help increase fermentation which could lower nitrate concentrations. On the other hand, acids and ammonia reduce fermentation and should probably not be used for drought-stressed corn.

Q. What is the feed value of drought-stress corn?

A. Assuming it was chopped at the correct dry matter and is low in nitrates, drought-stressed corn silage is a reasonably good feed for cattle. It usually has more fiber and less grain than normal silage but the fiber is usually more digestible. The net result is that the energy value is usually slightly lower than normal silage and additional grain supplementation might be needed. Drought-stressed corn silage must be tested for nutritional value so that appropriate diet changes can be made.

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Testing for Nitrates
With the dry conditions in many areas in Ohio, crop growth has been severely affected and producers are considering using grain corn for forage. With the dry conditions, concerns have arisen about the potential for nitrate toxicity to animals. Conditions favorable to high nitrate concentration and feeding guidelines are described in the attached OSU Extension fact sheet titled "Nitrates in Dairy Rations" (http://ohioline.osu.edu/as-fact/0003.html).

Options for testing for nitrates are sending samples to feed analytical laboratories or using field test kits. Many analytical laboratories test for nitrates with a very fast turnaround time for results, but the samples must be properly handled (call the laboratory for instructions before the sample is sent). The following laboratories, among many others, offer nitrate analyses:

-Holmes Laboratory, Millersburg, OH, 800- 344-1101

-DairyOne, Ithaca, NY, 800-344-2697

-Cumberland Valley Analytical Services, Maugansville, MD, 800-282-7522.

Field test kits are available from different suppliers, but many of these are designed for water and must be modified for feed. Some suppliers of test kits are:

-International Ripening Co., -800-472-7205
-Nasco, 800-558-9595
-Neogen, 800-234-5333
-Nitrate Elimination Co., Inc., 800-648-7283.

To use the test kits designed for water to analyze for nitrates in corn plants, follow the procedure below:

1) Chop a representative sample of corn plants into very small pieces and mix

2) Weigh about 20 grams of the chopped corn silage and add 100 ml of distilled water

3) Let the mix stand for about 10 minutes, shake vigorously, and repeat this step two or three times (a better approach would be to mix the silage and water in a blender)

4) Remove 5 ml of the solution and add 95 ml of distilled water and mix

5) Run the test using the kit what you have purchased.

6) Convert the results to a dry matter basis, using one of the following methods:

a) Test result x 400 = ppm (DM basis, assuming the corn is 30% DM)
b) Analyze the DM content of the corn silage and use the following equation:
    (Test result x 120) / DM proportion, expressed as a decimal = ppm

*If values are below the detection limit of the assay, nitrate concentration in the plants should not be a problem for the animals.

In addition to those options, the Ohio Department of Agriculture is offering farmers an opportunity to have forage tested for nitrates at no cost. A one-gallon ziplock bag representative of a field of storage facility is the recommended sample size. The turn around time for samples should be within 24 hours or less once a sample is received. Samples can be dropped off or mailed to ODA at 8995 East Main Street, Reynoldsburg, Ohio 43068. For more information call 800-282-1955.
 

Sincerely,
 

Mike Hogan Extension Agent Agriculture & Natural Resources  Community Development

Ken Simeral Extension Agent Agriculture & Natural Resources Community Development

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Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.
TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868