Characteristics of nitrogen and phosphorus losses from swine production systems in Jiulong River watershed

Huge losses of nitrogen and phosphorus from the livestock production systems are known as the waste of resources and the sources of the environmental quality problems. Nutrient balance at farm level is an important tool to study the environmental problems associated with livestock production. A nutrient balance was constructed for 92 swine production systems of Jiulong River watershed, Fujian Province. The majority of the farms exhibited substantially greater nutrient inputs than nutrient managed outputs and it was in the status of an overaccumulation of nutrients; the nutrient imbalance decreased with farm scales; ecological production was a preferred mode to make better use of resources and decrease the losses of nutrients; management of feed and manure was helpful to balance the nutrients of livestock farms.