Portable Pens

This is a type of "pasture production" system and is a traditional approach to animal agriculture. The portable pens can be easily moved or relocated periodically.

Advantages:

• This system is attractive because there is no liquid leaving the pen, so there is no chance of any such liquid going into a surface stream.
  
• In other words, the system would essentially entail zero-discharge, as there would be no collection or management of any of the manure or effluent (the manure would be directly deposited on to the plant material within the pen area and worked into the material through the pigs' hoof or rooting action).
  
• The sytem is very easy to use, as pens need to be relocated only every 3 to 6 months, and no other system component is needed.
  
• The addition of manure to the land within the corrals could increase soil fertility; rooting and hoof action could also improve soil quality.
  
• The system has potentially very low capital & operating costs.
  

However:

• Portable pens cannot be used on steep or rough terrain, meaning that such systems will be limited to fairly flat areas (unfortunately, on Tutuila, there are numerous competing land uses for flat terrain).
  
• Portable pens should not be used over ground that is highly porous, due to concerns regarding possible groundwater contamination.