The University of Georgia Cooperative Extension released on May 26 a resource addressing frequently asked questions about nitrates in grazed and harvested forages. The publication outlines the causes, risks, testing methods, and management strategies related to nitrate accumulation in forage crops.
Nitrates are compounds composed of nitrogen and oxygen that occur naturally in soil and water, as well as commercial fertilizers. Plants absorb nitrates as their primary form of nitrogen. Under stressful growing conditions such as drought, excessive fertilization, or cold weather, plants may accumulate high concentrations of nitrates that can be toxic to livestock if consumed.
The document explains that all plant species can accumulate high levels of nitrates under certain conditions. However, some forage crops—such as bermudagrass, tall fescue, corn, pearl millet, sorghum species, oats, ryegrass—and several common weeds are more likely to reach toxic nitrate levels. The resource provides detailed guidance on interpreting laboratory test results for different forms of nitrate measurement and offers recommendations for safe feeding based on those results.
Testing for nitrates can be conducted through laboratory analysis or with in-field test strips. Laboratory tests are considered more accurate but represent only the sample at the time it was collected; field tests should be used primarily as screening tools, with any positive result confirmed by lab analysis. The publication also addresses how nitrate concentrations do not significantly decrease when stored as hay but may reduce during ensiling—though this is not guaranteed to make feed safe.
To prevent toxicity or poisoning from high-nitrate forage material, the Extension recommends split fertilizer applications throughout the season rather than applying all at once; delaying harvest until plants have resumed growth after stress events; adjusting grazing management practices; providing clean water and mineral supplements; limiting access to high-nitrate areas; and monitoring livestock closely for symptoms such as rapid breathing or bluish mucous membranes.
Treatment options are limited due to the rapid onset of acute toxicity symptoms but may include veterinary-administered methylene blue solution intravenously if caught early enough. For further information or guidance regarding nitrate management in forage systems, readers are encouraged to contact their local Extension office.
