It is often a challenge for an animal feeding operation to know when it has achieved environmental “sustainability”. Typically, environmental sustainability is measured in terms of compliance with environmental regulations – receipt of appropriate permits, completeness of records, and implementation of some minimum set of best management practices. Such measures of regulatory compliance represent an indirect indicator of environmental sustainability focused on only one aspect of nutrient management on a swine farm.

Whole farm nutrient balance (WFNB) is a tool for defining the efficiency of nutrient utilization by the entire farm operation including animal and crop production components. Similar to a feed efficiency measure used by many pork producers (lbs of feed per lb of gain), WFNB provides an overall farm measure of nutrient use efficiency – one indicator of environmental sustainability.
The project team applied the principles of WFNB to 13 swine operations for two one-year periods (2006 and 2007). These farms ranged in size from 2,000 to 16,000 head finishing capacity with most farms being wean to finish or feeder pig to finish. The experiences and knowledge from these on-farm experiences are the basis of an educational resource for helping pork producers measure their nutrient efficiency and identify practices that can provide measurable environmental benefits.
On average, 1.5 lbs of nitrogen entered these farms from off-farm sources for every 1 lb of nitrogen leaving as managed outputs or products. From a phosphorus perspective, a very similar performance level was observed. These farms demonstrated significantly better nutrient efficiency over previous studies.
Feed was the single largest source on average of all nutrient inputs. Feed management decisions will typically have the largest single influence on nutrient efficiency of swine farms. Manure storage system selection and cropping system nutrient plan implementation were also observed to be important. However, improved crop nutrient planning by the 13 participating farms had little to no opportunity for additional improvements in farm’s nutrient efficiency because of currently implemented practices. Factors such as animal density (head per acre) and farm size demonstrated limited to no value when trying to explain a farm’s nutrient efficiency.