Intensified agricultural systems may be defined as those which involve either a significant reduction in fallow length (intensity of cropping) or the construction of permanent agronomic facilities that allow continuous cropping.
Archaeological, ethnohistoric and ethnographic information suggest these intensive systems may be classified into (1) those utilizing some form of water control for the continuous cropping of taro; (2) short-fallow, permanent field systems in dryland areas; and (3) arboriculture (the cultivation of trees and shrubs) associated with long-term storage of starch pastes.
Lo‘i Kalo (terraced pondfields)
A technological invention by Hawaiian Polynesians was the development of their extended stone-faced, terraced lo‘i (pondfields) and their accompanying ‘auwai (irrigation systems) for the intensive cultivation of wetland kalo (taro.) (Kelly)
Here, a water source such as a spring or stream is tapped and diverted to irrigate a set of artificially terraced or bunded, flooded fields. Such pondfield irrigation systems vary in scale and hydraulic complexity, ranging from small sets of 10 fields or less, to extensive valley-bottom complexes with hundreds of fields. (Kirch)
The irrigation ditches and pondfields were engineered to allow the cool water to circulate among the taro plants and from terrace to terrace, avoiding stagnation and overheating by the sun, which would rot the taro tubers.
Lt. King of Captain James Cook’s 1778 expedition noted, “… the inhabitants (of Kauai) far surpass all the neighboring islanders in the management of their plantations.”
“… these plantations were divided by deep and regular ditches; the fences were made with a neatness approaching to elegance, and the roads through them were thrown up and finished in a manner that would have done credit to any European engineer.”
In 1815, the explorer Kotzebue added to these descriptions by writing about the gardens and the artificial ponds that were scattered throughout the area:
“The luxuriant taro-fields, which might be properly called taro-lake, attracted my attention. Each of these consisted of about one hundred and sixty square feet, forms a regular square, and walled round with stones, like our basins.”
“This field or tank contained two feet of water, in whose slimy bottom the taro was planted, as it only grows in moist places. Each had two sluices. One to receive, and the other to let out, the water into the next field, whence it was carried farther.”
An acre of irrigated pondfields produced as much as five times the amount of taro as an acre of dryland cultivation. Over a period of several years, irrigated pondfields could be as much as 10 or 15 times more productive than unirrigated taro gardens, as dryland gardens need to lie fallow for greater lengths of time than irrigated gardens. (Kelly)
Dryland Field System
In dryland field systems, field boundaries were permanently demarcated and soil fertility was maintained through labor intensive mulching. Taro was planted in rotation with yams, sweet potato, bananas and other crops. This systematic cultivation of dryland crops in their appropriate vegetation zones are exemplified by the Field Systems in Kona, Kohala, Kaupō, Kalaupapa and Ka‘ū.
Crops were matched with their most compatible vegetation zones, trees had adequate spreading space, and double cropping was utilized where appropriate. (Kelly) Short-fallow dryland systems that were the most demanding of labor inputs. (Kirch)
Captain Charles Wilkes of the American Exploring Expedition, which visited Hawai‘i in 1840, noted: “… a mile back from the shore, the surface is covered with herbage, which maintains cattle, etc; and two miles in the interior there is sufficient moisture to keep up a constant verdure.”
“Here, in a belt half a mile wide, the bread-fruit is met with in abundance, and above this the taro is cultivated with success. At an elevation of between two and three thousand feet, and at the distance of five miles, the forest is first met with.” (Wilkes)
Farmers found, farmed and intensified production on lands that were poised between being too wet and too dry. Archaeological evidence of intensive cultivation of sweet potato and other dryland crops is extensive, including walls, terraces, mounds and other features.
The fields were typically oriented parallel to the elevation contours and the walls; sometimes these were made up of a grid of rain-fed plots, defined by low stone field walls built, in part, to shelter sweet potatoes and other crops from the wind.
Since the dryland technique was away from supplemental water sources, this was truly dryland agriculture. There was no evidence to level terraces as in irrigated pondfield systems (taro lo‘i,) and there was no evidence of water control features or channels; so the conclusion was the system was strictly rainfed.
Arboriculture (the cultivation of trees and shrubs)
‘Ulu (Breadfruit) was the primary Polynesian tree crop. It was a canoe crop – one of around 30 plants brought to the Hawaiian Islands by the Polynesians when they first arrived in Hawaiʻi.
“The bread-fruit trees thrive here, not in such abundance, but produce double the quantity of fruit they do on the rich plains of Otaheite.” (Captain James Cook, 1779)
“This tree, whose fruit is so useful, if not necessary, to the inhabitants of most of the islands of the South Seas, has been chiefly celebrated as a production of the Sandwich Islands; it is not confined to these alone, but is also found in all the countries bordering on the Pacific Ocean.” (Book of Trees, 1837)
The numerous clones of breadfruit with differing properties of yield, fruit characters, timing of harvest, and other aspects of morphology (leaf shape, etc.) provide a classic example of genetic innovation through selection.
Since breadfruit produces high yields in a short harvest period (usually two times per year), the crop generally cannot be completely consumed at the time of harvest.
In some parts of Polynesia and Micronesia, this problem was overcome by technological innovation of anaerobic fermentation and subterranean storage of the uncooked fruit in silos, where the fermented paste may be kept for periods of several years to be consumed as required. (Kirch)
This emphasis on storage also permitted the accumulation of large reserves, and control of these lay in the hands of the chiefly elite, who deployed these resources to political ends.
Thus, in Polynesian arboriculture we have an example of both genetic and technological innovation providing substantial opportunities for particular individuals within society to increase, concentrate, and gain control over surplus production, without the need for significantly increased labor inputs. (The inspiration (and much of the information) for this post came from research from Dr Marion Kelly and Dr Patrick Kirch.)