Promoting the Use of Local Resources

Compost tea trials

Hawaiʻi imports over 85% of the food consumed and is estimated to have less than a seven day supply of food on hand at any given time. At the same time, the cost of imported fertilizers increased from $300 to $1000 per ton between 2006 and 2008, which increased the demand for local organic fertilizers in order to keep local producers competitive. Improved food security in the Pacific islands requires that a cost effective  local fertilizers be available to growers, and that growers know how to utilize them appropriately. Replacing imported fertilizers with local resources is the highest research, education and development priority identified by the 100 participants of the WSARE Hawaiʻi Subregional conference held in Kona, Hawaiʻi in 2008.

Reducing Pacific Island Growers’ Reliance on Off-Island Fertilizer Sources through Improved Awareness and Efficient Use of Local Inputs. USDA WSARE Research and Extension program. $284,070. 2011-2014.

Vermicompost-based media to enhance organic vegetable seedling vigor, yield, crop quality and grower profitability. USDA Organic Research and Extension Initiative. 2009-2013. $351,000.

Enhancing Phytonutrient Content, Yield and Quality of Vegetables with Compost Tea in the Tropics. USDA WSARE Research and Extension program. 2007-2011. $162,500.


Composting is a controlled form of biological decomposition in which organic materials are combined and managed to produce a stable or mature product (compost) that can promote plant growth several ways. However, compost is relatively low in nutrients, and large amounts (20-40 tons per acre) generally need to be applied in the field to observe short term changes in soil quality or plant growth. The transportation and production costs associated with these application rates can be prohibitive. Innovative use of smaller quantities of compost can improve cost effectiveness and still provide benefits to plants. Our lab currently has two funded projects seeking to improve the cost-effective use of compost.

Compost Projects

Compost Resources


Invasive algae species have become a serious problem on reefs in the tropical Pacific, as they effectively compete for oxygen and sunlight killing corals and replacing valuable seaweed used for food by fish and people. Sustained efforts to remove the algae by various groups has produced millions of pounds of the material that must be disposed of. Efforts to compost the material and/or apply it directly to fields indicate that invasive and cultured algae can contribute to plant nutrition (particularly potassium (K)) and growth. However, preliminary analyses indicate that mineral nutrient and heavy metal content of these algae differ dramatically by species (some have almost no K) and location of growth. We are currently working to improve our knowledge of the variation in nutrient, salt and heavy metal content of the material among species at different locations must in order for growers to effectively utilize this promising source of local, organic potassium and micronutrients.


Tankage produced locally from fish waste, carcasses and expired supermarket meat has been investigated as a soil amendment by CTAHR researchers since at least 1995. However, little information is available to guide agricultural professionals in making recommendations regarding the product to their clentele. Molokai extension agent Alton Arakaki has taken the lead in research and outreach regarding effective use of this inexpensive, locally available product. In response to agent and grower request, our lab has begun to develop additional data. Work has focused on combining the high nitrogen, low C:N tankage product with high carbon commercial composts to ameliorate the short term adverse impact of high C:N in composts and optimize fertilizer use efficiency of the meat product.