Crops such as oat hay, sorghum, corn, sudangrass, Johnsongrass, beets, and weeds such as carelessweed, kochia, pigweed, Russian thistle, and nightshade, are examples of plants that accumulate nitrate. There are many more. Plants containing more than 1.5 percent nitrate (as KNO3) dry weight may be lethal to livestock. Sublethal effects may occur in livestock from eating feed containing between 0.5 and 1.5 percent nitrate. Nitrate poisoning can also occur in animals that eat nitrate fertilizers, machine oil, and some natural well and pond waters.
Plants differ in their ability to accumulate nitrate. The type of soil, availability and the form of nitrogen present in the soil, various environment factors and chemical or physical plant damage influence the amount of nitrate in many of these plants. For example drought conditions, frost, or treatment of nitrate-accumulating plants with 2,4-D may cause plants to accumulate excessive amounts of nitrate. Nitrate accumulates primarily in the vegetative tissue of plants while the seed remains safe.
Where and When Nitrate Poisoning Occurs
How It Affects Livestock
The amount of plant material required to poison an animal depends on the amount of nitrate in the plant and, to a lesser degree, on the rate at which the plant is eaten. Many factors affect toxicity, but in general about 0.05 percent of an animal's weight of nitrate is near a minimum lethal dose. Poisoning occurs primarily in ruminants.
Signs and Lesions of Poisoning
How to Reduce Losses