Nitrogen is a basic building block of proteins and an essential nutrient for animal and plant growth. However, nitrogen in the form of nitrate (NO3) and in excessive amounts can cause l ivestock to ea t less, loose weight, abort fetuses, or even die. Nearly all plants are capable of accumulating toxic l evels of nitrate. However, excessive nitrate concentrations usually only occur when plants are growing in moist nitrogen-rich soils or in cloudy overcast weather. Some plants ar e more l ikely to accumulate nitrates t han others. The key to reducing livestock risk of nitrate toxicity is t o understand the conditions that lead to nitrate accumulation in plants.