About 20 elemental nutrients are essential for plant growth. Some of these nutrients are supplied naturally by air, water, and soil. Fertilizers and manures are used to supplement the natural supplies. When nutrients are used correctly they are very beneficial, but in the wrong place at the wrong time, they become pollutants. Both groundwater and surface water are very vulnerable to pollution.
Water is one of out most valuable resources, and protecting it is an important concern.
Because they stimulate unwanted algae growth, nitrogen and phosphorus are the nutrients most often blamed for degradation of surface water in North Carolina. A portion of the excess nitrogen and phosphorus enters water from agricultural fertilizers and manures. Nitrogen dissolves in water and is carried in runoff and groundwater. Phosphorus is held tightly by soil clays and transported mainly by erosion. Like elemental nitrogen, nitrate is not held by the soil.