Forage crops can accumulate toxic amounts of nitrate (NO3). High nitrate has been reported in cereal grains (oats, rye, wheat, barley, triticale, etc.), bromegrass, orchardgrass, fescue, sorghum, sudangrass, millet, corn, sweetclover and alfalfa. Several weeds, such as kochia, lambs-quarter, pigweed, quackgrass and Russian thistle, can also have high nitrate levels, especially when growing under adverse conditions.

Nitrogen from the soil is taken up by plant roots in the form of nitrate. Plants convert nitrate (NO3) to nitrite (NO2), which in turn is converted to ammonia and then to amino...