Under unfavorable growing conditions, especially drought, this conversion process is retarded, causing the nitrate to accumulate in the stalks, stems and other conductive tissue. The highest concentration of nitrate is in the lower part of the stalk or stem. If moisture conditions improve, the conversion process accelerates and within a few days nitrate levels in the plant return to normal. Not all drought conditions cause high nitrate levels in plants. If the supply of soil nitrates is in the dry soil surface, plant roots will not absorb nitrates.
Some soil moisture is necessary for absorption and accumulation of the nitrates.
Nitrate Toxicity in the Animal Like plants, ruminant animals also use the nitrogen in nitrates to make protein. Conversion is made by bacteria in the rumen. Nitrite, one of the intermediate products in this conversion, is the cause of nitrate poisoning. When this happens, nitrite accumulates and is absorbed into the bloodstream. Cattle are much more likely to be affected than are sheep or horses.