Unique Hawaiiian farming system being revived: kalo growing in kukui mulch

 

While early Hawaiian agriculture clearly grew out of Polynesian farming systems, these islands developed a unique food-production structure quite different from those elsewhere in the Pacific.

Ethnobotanist and forest ecologist Noa Kekuewa Lincoln reviewed that uniqueness in a book chapter, “Pakukui: The productive fallow of ancient Hawaii,” printed in the book Farmer Innovations and Best Practices by Shifting Cultivators in Asia-Pacific.

Kukui (left) and Hala trees. 
Jan TenBruggencate photo.

“The Hawaiian Islands, one of the endpoints of Polynesian settlement of the Pacific, saw the development of unique agricultural advances that have not been seen anywhere else,” he wrote.

While flooded taro paddies (kalo,) hilled sweet potato fields (‘uala) and garden plots with sugar cane (ko) and fiber plants like wauke and mamaki are well understood, the importance of tree crops—agroforestry—has perhaps been overlooked, he argues.

“Although a robust literature and investigation of Hawaiian agriculture exists, arboriculture is severely underrepresented. This had led to a simplified understanding of Hawaiian arboriculture with an emphasis on permanent, breadfruit-dominated arboricultural systems.”

It may be that Western viewers look at agroforestry through shaded lenses, missing key features. For example, focusing only on foods, oils, medicines and fiber may miss key contributions of some tree crops, he suggested.

“In some regions, it may be that Hawaiians planted trees specifically to accumulate fertility. In these systems, very fast-growing woody plants that decomposed quickly, such as candlenut and hau, were cultivated,” he wrote.

Candlenut or kukui (Aleurites moluccanus) is and was an immensely useful tree, providing food for humans and livestock, oil for many purposes, dyes, medicine and much more. 

Less well understood is its value as a mulch. In a culture without Western fertilizers, mulches were of inestimable value. Mulches of kukui and other plants were stamped into the muds of kalo fields, where they rotted and improved fertility.

“In a recent experiment we grew taro in pure mulches of candlenut, sugar cane, and hau (Hibiscus tiliaceus), and the growth in candlenut mulch was by far the largest (by ~150%), despite it having the lowest nitrogen content of the three treatments,” Lincoln wrote.

Kukui leaves, branches and logs could also be used to create soils on solid lava. A mulch pit filled with kukui was called a pakukui.

“In these situations, litterfall was gathered into relatively impermeable pits in the lava and composted in order to create a growing medium. Local organic waste and small amounts of soil that could be excavated nearby was added to these enclosures, or pa, to aid in the rotting of composts.”

The system is similar to but larger than the manavai planting technique in Rapa Nui, where circular walls of stone protected small planting areas in rugged windswept environments. Manavai were also used for taro, as well as banana and sugar cane. 

The use of the pakukui led, Lincoln said, to a shifting agricultural pattern, in which farmers would be growing crops in some fields while other were composting. That contrasted with areas with breadfruit forests, which would be harvested year after year.

Kukui helped to make poorer soils much more viable for agriculture, though only for intermittent use. With the decline in Hawaiian population, the practice appeared to have died out.

“Following European contact in Hawaii, several forms of traditional agriculture rapidly declined, primarily due to the population crash that accompanied the introduction of foreign diseases. Among the practices that declined rapidly was the pakukui,” he wrote.

But the agricultural system still has value, and should be revived, he said. He is working with partners in Hamakua to convert “a long-established pasture back into a candlenut forest to reinitiate the practice of nutrient accumulation and natural fertilization to realize significant taro productivity.”

Lincoln works with Indigenous Crops and Cropping Systems in the Tropical Plant and Soil Sciences Department, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. His pakukui chapter was published in December 2023.

© Jan TenBruggencate 2024