Principles of Composting Pig Waste in American Samoa

Composting is a natural process where microorganisms decompose organic material in an aerobic environment, turning waste into a stable soil amendment. It occurs in two stages: the primary stage, with high biological activity and temperature, and the secondary stage, where compost stabilizes. Proper conditions like material mix, moisture, porosity, and temperature must be controlled for efficient composting and odor prevention.

​

Material Mix

A proper compost mix requires a balanced carbon-to-nitrogen (C/N) ratio, ideally above 25:1, to minimize odors and support microorganisms. Pig waste alone has a low C/N ratio, so high-carbon materials like wood chips, sawdust, or coconut husks must be added for effective composting. Foul odors indicate the need for more carbon-rich materials.

​

Moisture Levels and Porosity

Proper composting requires adequate moisture (50–60%) and a porous structure for oxygen flow. The compost should feel moist but not release water when squeezed. Aerobic bacteria need oxygen, so 35–50% of the pile should have open spaces for airflow.

​

Temperature

Aerobic bacteria involved in composting function in two temperature ranges: mesophilic (up to 100°F) and thermophilic (up to 155°F). As bacteria break down materials, heat is generated, accelerating decomposition. However, temperatures above 155°F can slow the process by deactivating the bacteria. Rising warm air allows fresh air to enter, maintaining an aerobic environment and expelling CO2. Sustained temperatures above 130°F for three days can kill harmful bacteria. While compost generates heat, proper management is essential to maintain optimal temperatures.

​

Compost Bin Operations

American Samoa’s hot and humid climate is ideal for composting, but protection from heavy rainfall is necessary. Compost bins made of hog panels and wire mesh help manage the process, with most piggeries needing 3–4 bins. The compost should be rotated every two weeks, and when properly managed, the process takes about eight weeks. Maintaining proper moisture levels is crucial for successful composting.

​

Here are a few clues your compost is too dry:

• Temperatures are too low

• Hand moisture test fails 

• It looks more dusty than like fresh soil

• There are ants in the pile

 

If a compost pile is too dry, microorganisms slow down due to a lack of water. To fix this, add water carefully without soaking the pile. Showering the compost or moistening layers while rotating helps maintain proper moisture. Avoid overwatering, as balance is key, and it may take a few days for the composting process to resume.

​

Screening & Use

After two months, compost should be ready for use and should appear dark brown or black. It can be screened using a wire mesh to remove oversized material, which can be reused in another compost bin. The compost serves as fertilizer, soil amendment, or mulch. However, caution is advised when handling it due to potential pathogens, and hands should be washed thoroughly afterward. Additional technical information regarding composting can be found at:

http://www2.ctahr.hawaii.edu/oc/freepubs/pdf/HH-13.pdf

http://www.mastercomposter.com/

http://www.vegweb.com/composting/

http://www.attra.org/attra-pub/farmcompost.html

​

Record Keeping

Keeping a log book helps ensure effective composting by tracking bin temperatures and wood chip usage. This data improves composting efficiency and waste management. Composting pig waste is a simple process that reduces health and environmental risks while producing organic fertilizer, reducing reliance on chemical alternatives.