Nitrates in Hail and Drought Stressed Crops
This year has provided above average precipitation for much of South Dakota, but there are still areas of the state that are classified in D0-D1 drought condition. As of July 29th, 28.89% of South Dakota is considered abnormally dry, with 3.61% being in a moderate drought. This may not be overly significant for some, but it means a change in management decisions for others. The other challenge in these areas and others is hail damage. Stressors such as drought and hail can increase nitrate levels in crops, resulting in a need to change how they are managed.
There are options available for use of stressed crops depending on the severity of the drought or hail. Evaluate the crop to determine which option is the most economical and will give the most opportunities to utilize the crop in the best manner possible.
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 that will give a positive or negative result for nitrates. If positive, the sample needs to be sent to an analytical laboratory for a quantitative analysis to determine risk. Contact SDSU Extension to determine the nearest office providing the test. If there is little or no nitrate present, salvaging the crop as livestock forage would be an excellent choice.
- Let the crop mature to see if it will produce grain or hay. 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.
- 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.
- 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% of the nitrate will be converted to ammonia if the process is done correctly. Always test the ensiled feed before feeding to livestock to ensure that nitrate levels are appropriate for the class of livestock.
- Incorporate it into the soil to increase organic matter. This provides the least economic return in the short run, but has the potential for long term positive impacts on the field.
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 the Nitrate Poisoning of Livestock: Causes and Prevention publication.