However, some soil microorganisms convert these compounds to nitrate, the mobile form of nitrogen in soils. Under some conditions, nitrate may leach below the root zone and eventually reach ground water. Unlike phosphorus, nitrogen can pose a direct threat to human health. Nitrite can interfere with the oxygen-carrying capacity of red blood cells and produce a condition known as methemoglobinemia. Because this condition primarily affects newborns and infants less than six months old, it is commonly known as infant cyanosis or blue baby syndrome.
Several practices minimize nitrate leaching from manure applications.
Most importantly, manure application rates should not exceed the nitrogen requirement of the crop. As a crop grows, its nutrient requirements changes. Applying manure when the crop needs nutrients reduces the risk to water supplies. Fall manure applications should be made to a cover crop which will take up the nutrients in the manure. The cover crop also reduces runoff and erosion.