Nutrient management

Take nitrogen (N) as an example. N arrives on farm generally in the five forms as shown in the following figure. Within the boundaries of the farm, there is a “Recycling” of nutrients between the livestock and crop components. Manure nutrients are recycled, at least in part, for crop production. Feed crop nutrients are in turn recycled as animal feed for livestock or poultry production. It is preferable that nutrients leave a livestock operation as “Managed Outputs” including meat, milk, eggs, crops, or manure transferred to an off-farm user. The balance between N inputs and managed outputs defines the quantity of N lost to the environment. Livestock operations that achieved a balance represent a potentially sustainable production system. In contrast, livestock operations with a significant imbalance can cause increased risk to environmental quality. Much of the N loss to air can are in forms of NH3 or N2O.