Rediscovering Hawaiʻi’s Ancient Agriculture: The Kohala Field System

by Jamie Dickman

Between news headlines of record-breaking temperatures and other signals of ecological collapse, it's easy to forget that the answers to our most pressing crises often lie buried in the past. Nowhere is this truer than in Hawai'i, where a largely forgotten history of sustainable agriculture has the potential to unlock a future of food sovereignty.

Before the arrival of Westerners, the most isolated archipelago in the world was entirely self-dependent, efficient, and sustainable. Unfortunately, most Indigenous Hawaiian agricultural knowledge was lost to cultural assimilation, but its remnants lie in the eroded mounds of the Kohala Field System archaeological site, and Native Hawaiian researchers are digging up the past.

Ulu Mau Puanui, a non-profit organization led by educator Kehaulani Marshall, works on rediscovering this knowledge by studying the Kohala Field System in partnership with people like resident scientist Noa Lincoln. Coincidentally, the lead researchers are uncovering the work of their ancestors.

In the northern region of Hawaiʻi Island, a small hill called Pu‘u Kahena is on the makai (seaward) side of the windy Kohala mountain road. From the vantage atop the pu’u, the ancient walls of stone and earth that characterize the Kohala Field System appear buried and almost forgotten. In every direction, there are rows and rows of centuries-old infrastructure.

“I don't think there's anywhere else in Hawaiʻi where, from a single point, you can see the scale and scope of what our ancestors were doing,” Lincoln says. “Even as someone who was well-versed in Hawaiian history and culture, I realized how wrong my perception of old Hawaiʻi was. I had this kind of Eurocentric description of Hawaiʻi as these small collections of villages, but when you see the field system, you see the work of a nation.”

Highly advanced agriculture developed here between 1450 and 1800, producing tens of thousands of tons of food on over 23 square miles (15,000 acres). At its peak, the Kohala Field System fed a thriving population of 20,000 to 30,000 people.

Lincoln, an expert in Hawaiian agroecology, has been one of the researchers at the forefront of this excavation, uncovering the lessons of the Kohala field system. This massive, ancient agricultural network defies the colonial narrative of Hawai'i as small and primitive.

Noa was introduced to the Kohala Field System 20 years ago as an educator at the Amy B.H. Greenwell Ethnobotanical Garden. This experience was transformative for his understanding of Hawaiian agriculture, which he describes as “shifting from this Western perspective of ecology as environments that are devoid of humans to thinking of humans as actors within ecosystems”— a shift in perspective that's gaining more traction among ecologists, environmental scientists and other academic scholars today.

Kohala is today's largest continuous intact site, although many abandoned field systems lie across the islands. Much larger field systems in Kona, Kaʻū, and Central Maui were destroyed by sugar plantations or development, as was the northern end of the Kohala Field System. For instance, Kaʻū, which is estimated to have been about 60 square miles or 37,000 acres, was three to four times bigger than Kohala.

The abandoned mounds of Kohala were “rediscovered” by archaeologists in the '60s, but it wasn't until 2008 that actual field research and restoration began. Many agricultural practices, like rock mulching (layering rocks atop soil to improve fertility), are determined through trial and error. Experimental studies of cultivation practices demonstrated that rock mulching, a traditional practice, led to significantly greater yields of sweet potato than did alternative methods, Kehaulani Marshall and her team declared in a 2017 research paper.

Lincoln’s introduction to the field system in the early 2000s sparked his interest in agroecology, particularly in how our natural environment shapes human societies and values and in turn, how those values shape how we choose to utilize our environment. Hawaiʻi’s unique socio-political history allows for studying societal evolution in a relatively closed system. An agricultural surplus supported the development of high-density populations and complex governance, making it the perfect model for studying interactions between the environment, agriculture, culture and social systems. Years later, Lincoln returned to school to earn his PhD at Stanford University on this topic.

When the first kanaka (Native Hawaiians) arrived on the islands, they brought crops and place-based knowledge of agriculture. As expert kalo (taro root) growers, they used their traditional methods of flooded wetland agriculture to grow food rapidly in areas where flowing surface water was available. However, the Hawaiian Islands are home to a wide variety of ecosystems, many of which are not found in the South Pacific Islands from which the Hawaiian people traveled. Polynesians who settled Hawaiʻi came from southeast Indochina, through New Guinea, and westward across the Pacific. Therefore, they had to adapt and develop new farming practices.

“If you're going to understand one thing about Hawaiian agriculture, it would have to be the diversity of systems. Hawaiʻi is one of the most ecologically diverse places on the planet,” Lincoln says.

Hawaiʻi Island alone has 27 of the 38 Holdridge life zones—a climatic and ecological classification system. The more Holdridge life zones, the more diverse a given area is. In Hawaiʻi Island’s case, it represents almost the entire rainfall gradient of the planet. Hawaiʻi only lacks cold life zones, like polar deserts, tundra, and taigas. Due to this diversity, Hawaiʻi has the world's highest rates of endemism (the state of a species only being found in a single location).

Lincoln explains the link between diverse climates and high rates of endemism: more varied geography offers a range of niches for species to adapt to and occupy. Hawaiʻi’s isolation also hastened the emergence of new species. “But rarely do I think we take the next step and consider that ecological diversity drove diversity in people as well,” he says. “Not in the sense that humans became new species since they came here, but in the sense of cultural adaptation and the divergence of knowledge and practices. The development of new and unique agricultural systems is a great example of that.”

Different planting methods were adapted to other soil types and zones, leading to distinct cropping systems and temporal uses of dryland areas. Hawaiian farmers employed diverse techniques to cultivate various habitats, adjusting their methods based on specific environmental conditions. Intensive wetland and dryland agriculture were influenced by topography, elevation, flowing water, rainfall, substrate age, and slope, leading to distinct variations across the islands.

Lincoln says the work he and other researchers do, such as his mentor Peter Vitousek or colleagues such as Aurora Kagawa-Viviani, is as diverse as the island, from studying the whole landscape’s climate to measuring the effects of a single agricultural wall. On an average day, winds can vary between 25 and 50 mph—entering the range of a tropical storm. The harsh conditions often make Lincoln wonder how early Hawaiians grew food in this environment despite studying the topic.

“A lot of the work is understanding how these environmental factors, like weather and climate, that we perceive as negative or as challenges and how they actually turned them into positive components of the system,” Lincoln says.

“For instance, the systems are characterized by common infrastructure, particularly long, linear mounds—low mounded walls, only two or three feet high,” he explains. “Even that small texture on the landscape creates turbulence in the air. It breaks up heavy winds, which carry moisture and encourages interaction with the land in a way that enhances moisture deposition.”

“Kilo” is a Hawaiian word that refers to observing and studying the natural world to understand the patterns and relationships that govern it. Through careful observation and study, the Hawaiians were able to develop new sustainable agriculture systems that relied on zero external inputs and were sustained for hundreds of years in balance with the land. The concept of kilo is also an essential part of Hawaiian spirituality, and it is believed that a deep understanding of the natural world and one's place within it is crucial for living a fulfilling and meaningful life.

 

Kohala’s type of large-scale food production using a labor-intensive rainfed system was new at this time, even globally. This agricultural style is not found in the rest of Polynesia, the origin of the earliest Hawaiians’ voyage, or anywhere else.

‘Uala (sweet potato) was the primary crop produced in the Kohala Field System. Using sugar cane as a windbreak, farmers could protect their sweet potato crops from strong winds and maintain a stable microclimate. The sugar cane leaves helped capture mist and rain, providing additional moisture for the crops. This type of intercropping is just one example of the system’s techniques.

The Kohala Field System also produced upland kalo (taro), uhi (yam), ‘ulu (breadfruit), mai‘a (banana/plantain), and kō (sugarcane), among other crops. Many of these native foods are available today through the Hawaiʻi ‘Ulu Co-op, a local farmer-owned enterprise working to revitalize traditional starches.

 

Agricultural practices evolved from simple forest plantings to slash-and-burn agriculture to complex infrastructure such as terraces and irrigation systems. The Kohala system was an intense network of walls and mounds that traverses a natural rainfall gradient: the lowest portions were arid, the middle mesic, and the upper portions were wet, allowing diverse crops to grow in a single area. So how did the Hawaiians continuously grow abundant food while replenishing the soils and relying on zero external inputs? This is one of the many puzzles Ulu Mau Puanui has to solve by experimentation. For instance, they have observed firsthand how the intensive array of walls and mounds interacted with wind, mist, sun and rain to alter the hydrology of the landscape, redistributing moisture and improving opportunities for cultivation.

For centuries, Native Hawaiians cultivated a sophisticated network of agricultural practices, producing food in harmony with the island's diverse ecosystems. These systems were both sustainable and regenerative and designed to support the land and the people indefinitely. However, the arrival of Western powers disrupted this balance, imposing a colonial logic that saw the land not as a living entity but as a resource to be extracted and exploited. Hence, the sugar plantations were built over cultivated Hawaiian fields.

The imposition of large-scale plantations in the 19th century destroyed many of Hawai'i's traditional agricultural systems, replacing them with monocultures that depleted the soil and displaced indigenous practices. This legacy of exploitation has left a scar on the land and the people, severing the connection between Hawaiians and their traditional food systems.

Hawaiʻi's food crisis is not just historical; it's ongoing. The push for tourism and real estate development continues to erode agricultural lands, while climate change exacerbates the vulnerabilities of a food system that was never designed to be resilient. Rising sea levels, unpredictable weather patterns, and the intensification of storms threaten the foundations of Hawai'i's food supply—the vast majority of which is transported by air or sea vessels.

 

Today, Hawai'i imports between 85 to 90 percent of its food from the continental United States, a dependency that leaves the islands vulnerable to global supply chain disruptions and price volatility. This isn't just a logistical challenge—it's a crisis of sovereignty. When a population loses the means to feed itself, it loses control over its future, becoming dependent on external forces with little regard for local needs or environmental health.

One might assume importing so much food is necessary, given Hawaiʻi's limited land and population size, much larger than it was pre-colonization. Hawaiian agriculture is in decline, and land is underutilized: Hawaiʻi lost 82,000 acres of farmland, 700 farms and 300 producers between 2017 and 2022, per the U.S. Department of Agriculture. Most of these farms were thought to be lost to development projects and pandemic shutdowns.

According to the USDA, Hawaiʻi still has just over 1 million acres of agricultural land in use. That's two-thirds of the area needed to feed Hawaiʻi's population of about 1.5 million (an acre per person is a conservative ratio for supporting a population).

 

Food sovereignty is defined as the “right of peoples to healthy and culturally appropriate food produced through ecologically sound and sustainable methods, and their right to define their own food and agriculture systems. It puts the aspirations and needs of those who produce, distribute and consume food at the heart of food systems and policies rather than the demands of markets and corporations” by the Declaration of Nyéléni from the first global forum on food sovereignty in Mali, 2007. 

“Replacing just 10% of the food we currently import would amount to approximately $313 million [in the Hawaiian economy],” Hawaiʻi’s Increased Food Security and Food Self-Sufficiency Strategy states. Increasing production and demand for locally grown foods is one of the strategy's objectives. The state currently estimates it spends $3.1 billion annually on imported food.  

A population without land ownership sustained the field systems' tremendous manpower requirements. The land was collectively cared for, and when the land was thriving, the people were thriving. This all changed with the arrival of Captain James Cook in 1778. Within just one generation, the Hawaiian population declined by 90 percent, primarily from novel diseases. This dramatic depopulation led to the abandonment of the Kohala Field System and its farming methods by the mid-1800s.

The mounds were built using local materials, including rocks, soil, and vegetation. Archaeological evidence shows that the field system was constructed and infilled over 250 years, with new mounds added as the population and demand for food increased. Many locals here, who are Native Hawaiian, can trace their roots back to this region. Their ancestors likely touched the same rocks that these walls are made of.

The voyagers who settled Hawaiʻi valued healthy environmental functions, reverence for nature and protection of certain areas from human impact. They passed on these values through stories, songs and chants. Now, Hawaiian culture holds a rich repository of knowledge about agricultural heritage, and by piecing together these bits of information, researchers can better understand the Kohala Field System and the society that formed it.

Learning and employing these ancient techniques may improve our agriculture, but novel environmental conditions likely pose barriers. Pests like rats and mice and certain diseases that can decimate crop yields were non-existent in pre-colonial Hawaiʻi. Wild pig populations were also better managed.

Researchers continue to piece together the story of this highly advanced agricultural system by revitalizing Hawaiian cultural practices with modern scientific research. Like their ancestors, Kehaulani Marshall and Noa Lincoln investigate the region's best-suited crops and most efficient cultivation methods.

 

Lincoln says part of his goal as a researcher is for people in Hawaiʻi to have happy, healthy lives and to develop agricultural systems that preserve our ecosystems' function, quality, and health—since human wellbeing is intricately linked to the quality of our environments.

He also hopes that suitable forms of land management will be recognized in the right place. European colonial efforts have displaced highly diverse ways of managing landscapes and growing food across the globe, forcing a one-size-fits-all approach of high-input monoculture. Monocultures have long been associated with degraded soil quality, necessitating stronger fertilizers and pesticides, a higher likelihood of crop diseases, and increased pollinator death rates.

“I think recently people have begun to question that and to acknowledge and realize that there's a lot of negative outcomes associated with the way we're growing food now, and that there is a need to work better with our ecosystems in terms of how we go about provisioning our societies,” he says. “I hope our work both inspires and informs those kinds of transitions.”

Ancient Hawaiians’ ability to learn from their environment helped them survive and thrive. With their few resources—literal sticks and stones —they established an exceptionally productive field system.

Even if not all ancient techniques can be applied today, the Hawaiian practice of kilo—observing, learning, and innovating—remains a vital lesson. To become more self-sufficient again, Hawaiʻi must expand local agriculture, diversify crops, and adopt innovative farming strategies for the islands’ unique, diverse ecology, including reintroducing native foods.

By combining fragments of knowledge from the past, Hawaiʻi can create a brighter, greener future grounded in its rich agricultural heritage.

 

Kehaulani Marshall (far left) and her research team at the Puanui Experimental Research Plot. For more information visit http://www.ulumaupuanui.org/about.html