Forage options when dealing with drought and hail stressed crops

BROOKINGS, S.D. – With nearly 60 percent of South Dakota impacted by drought and now some fields receiving hail damage, many growers are faced with decisions on how to best utilize drought and hail stressed crops.

“Stressors such as drought can increase nitrate levels in forage crops, resulting in a need to change how they are managed,” explained Adele Harty, SDSU Extension Cow/Calf Field Specialist. “Forages which have hail damage may no longer be viable for grain crops, therefore utilizing them for a forage crop may be necessary.”

Harty added that depending on the severity of the drought or hail there are options available for use of stressed crops as forage.

“Evaluate the crop to determine which option is the most economical and will give the most opportunities to utilize forage from the crop in the best manner possible,” Harty said.

Options, in likely order of use from least to most damaged crops include:

• Test the crop for nitrates to determine if it can safely be used as feed for livestock.

“SDSU Extension has a Nitrate Quick Test for Forages that will give a positive or negative result for nitrates,” she said.

If positive, the sample needs to be sent to an analytical laboratory for a quantitative analysis to determine risk. If negative, nitrates are not present and it is safe to feed.

Harty encourages livestock and forage producers to contact SDSU Extension to determine the nearest office providing the test.

“If there is moderate to no nitrate present, salvaging the crop as livestock forage would be an excellent choice,” she said.

Depending on the specific level of nitrate present, there are options for blending it with feeds that do not contain nitrates to reach safe levels.

Non-pregnant animals can tolerate higher levels of nitrate than pregnant females, so changing the class of cattle that the forage is fed to may be necessary.

• If it won’t make adequate grain and can’t be grazed, harvest the crop for hay.

Test for nitrates and have a feed analysis done to determine nutritional value for proper inclusion in a ration.

“If damage is severe, make sure that it will be worth the diesel, supplies and time to make hay,” Harty said.

• Let the crop mature to see if it will produce grain.

If they will not produce adequate grain, many crops can be grazed, if necessary precautions are taken (e.g. nitrates) and water and fencing are available.

• Harvest the forage for silage. If nitrates are present, the fermentation process will convert a portion of the nitrate into ammonia, thereby decreasing the overall risk, however it will not completely remove nitrate. It is critical that it is ensiled properly to ensure the best environment for fermentation.

“A rule of thumb is that 20-50 percent of the nitrate will be converted to ammonia if the process is done correctly,” Harty said. “Always test the ensiled feed before feeding to livestock to ensure that nitrate levels are appropriate for the class of livestock.”

• In a worst case scenario, where the crop is too damaged or too high in nitrates, consider spraying it out and leaving it for soil cover and reseed directly into it when you get moisture.

Precautions need to be taken when feeding forages that contain nitrates.

Details about safety levels and utilizing feeds within different ranges of nitrate content are outlined in “Nitrate Poisoning of Livestock: Causes and Prevention” which can be found on iGrow.org.

To answer specific questions contact Harty at 605-394-1722 or adele.harty@sdstate.edu, or Ken Olson, Professor & SDSU Extension Beef Specialist at 605-394-2236 or Kenneth.olson@sdstate.edu.