The 2011 ASHS Annual Conference

Reducing grower reliance on off-island inputs to promote plant nutrition has been identified by industry as a high priority in efforts to improve agricultural sustainability in Hawaii. A variety of knowledge gaps exist that prevent producers from using more locally produced amendments in their fertility program. This presentation will focus on recent trans-disciplinary efforts at the University of Hawaii to improve our understanding of factors that affect variability in the quality, application, efficacy, and cost effectiveness of locally produced composts, vermicomposts, rendered animal products, and algae in Hawaii. A series of greenhouse, experiment station, and on-farm trials have supported several conclusions, including: 1) aqueous extracts of vermicomposts and high quality, farmer-produced thermophilic composts can effectively improve crop growth and reduce costs associated with the use of these inputs; 2) replacement of peat and other imports with local materials in vegetable seedling production have the potential to improve seedling vigor and reduce costs in the long term; 3) commercially produced rendered meat products, alone and  in combination with commercial composts, is a valuable local source of nitrogen; and 4) invasive algae from coral reef remediation may provide a significant source of potassium in the near term, but K content of algae is highly dependent of species and location of growth.