June 12, 2018

Quite a few well-intentioned academics, more often than not in the social and ecological sciences, do us no favor by over romanticizing the pre-European contact past of Hawai‘i’s agriculture.

By Bruce Mathews, dean of the College of Agriculture, Forestry and Natural Resource ManagementUniversity of Hawai‘i at Hilo.

Sepia colored old print of valley with farmland.
He‘eia Valley, O‘ahu, 1910.
Bruce Mathews
Bruce Mathews

Hawai‘i rightly takes great pride in its rich agricultural history, the mālama ‘āina (deep care, stewardship, and respect for the land) of the Native Hawaiians, and no doubt much can be learned from the past. This being said, most conservation and resource management discussions in Hawai‘i pertaining to the revitalization of local agriculture tend to be far too insular, and focused on Eden-like interpretation of the past and anecdotal commentary for impactful progress to be made on viable paths forward. Yes, pre-European contact agriculture was self-sufficient, organic by practice, and did not rely on external inputs, however many bio-cultural, technological, and socio-political parameters have changed since that time. And there is strong evidence that pre-European contact agriculture and aquaculture had much greater impacts on Hawai‘i’s environment than previously thought (Kirch, 1982; Anderson et al., 2017). Native Hawaiian upland field systems based largely on intensive ‘uala (sweet potato) cultivation in the highly valued locations of greater natural soil fertility would have eventually run into sustainability challenges induced by gradual soil nutrient depletion (Vitousek et al., 2004; Hartshorn et al., 2006). In this regard it is also worth noting that no till aboriculture/agroforestry based on cultivation of ‘ulu (breadfruit) trees had some distinct environmental and subsistence agriculture advantages and should be further investigated (Rolett, 2008).

It’s time to test your soil!

By Chantal Vos, Researcher, and Norman Arancon, Associate Professor of Horticulture.

Norman stands in large sweet potato field.
Norman Arancon collects leaf samples from sweet potato field. Photo by Chantal Vos.

Sweet potato (Ipomoea batatas, L.) production along the Hamakua Coast can be increased by addressing nutrient imbalances in the soil. Sweet potato is an important crop in Hawai‘i both for local consumption and as an export crop and more than 90 percent is produced along the Hamakua Coast on the island of Hawai‘i (Miyasaka and Arakaki, 2010). Most commercial sweet potato farmers on Hawai‘i Island do not test their soil or crops on a regular basis for potential nutritional problems. Fertilizers are often applied indiscriminately based on prior experience or current practice from other growers, whether these areas have been cropped for many years or are newly cleared for cultivation. Soil fertility is often not optimal, even on land that has never been cultivated with sweet potato (virgin land). During crop production, available nutrients are lost through leaching, run-off, and crop harvest. Nutrient balances are distorted, and fallow periods have demonstrated limited capacity to adequately restore and build soil fertility. This being said, fallows will generally reduce many disease and pest problems (Bennett et al., 2012).