Best Management Practices for Agricultural Nutrients

About 20 elemental nutrients are essential for plant growth. Some of these nutrients are supplied naturally by the air, water, and soil. Fertilizers and manures are used to supplement the natural supplies for optimum crop growth. When nutrients are used correctly they are very beneficial, but when they are used 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 our 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. They promote excessive algae growth, which can cause fish kills, taste and odor problems, and reduce recreational uses of water resources. Sediment can also cause problems and is the number one pollutant of water resources in North Carolina.

Nitrogen dissolves in water and therefore is readily carried from application areas to surface and groundwater. Nitrogen in the nitrate form is the main threat to groundwater quality because it is not held by the soil and can leach through the soil and into the groundwater where it can contaminate well (drinking) water and eventually move into streams. Excessive nitrates in drinking water are a health hazard, especially to infants. Phosphorus is held tightly by soil particles and is transported mainly on eroded soil particles, but soluble (dissolved) forms of phosphorus can also enter water resources. Agricultural production can add nitrogen, phosphorus and sediment to water resources. This publication outlines ways to minimize the movement of nutrients and sediment to surface and ground waters while maintaining healthy, productive crops.