Noa Kekuewa Lincoln

Nitrogen fixation during decomposition of sugarcane (Saccharum officinarum) is an important contribution to nutrient supply in traditional dryland agricultural systems of Hawai'i

Nitrogen (N) is unique among essential elements required for life, in that it must be fixed from the vast atmospheric reservoir before most organisms can use it. Prior to industrial nitrogen fixation, many agricultural systems were limited in their productivity by N. What sustained N in the ancient Hawaiian dryland (rain-fed) agricultural systems that lacked legumes or other known significant N inputs? N-fixation during sugarcane (Saccharum officinarum) growth and litter decomposition was examined in settings representing pre-European Hawaiian agriculture. We did not detect associative N-fixation during the growth of five Hawaiian sugarcane cultivars. In contrast, N-fixation during the decomposition of leaf and stalk material was important. We found that the depth of the mulch layer significantly affected N-fixation levels during decomposition; values of N-fixation in different depths of senesced leaf litter ranged from 0.69 to 1.36 gN/kg of litter integrated over the lifetime of decomposition. Compared to senesced leaf litter, N-fixation during decomposition of non-senesced leaf litter was ∼77% and stalk material ∼140% per unit mass. Peak rates of N fixation occurred between 200 and 400 days of decomposition, and ranged from 1.37 to 3.27 gN/kg/yr. Our empirical results were extrapolated to represent the traditional Hawaiian cropping system; we calculated N-fixation inputs of 4.8–39.0 kgN/ha/yr, with fixed N adding 17–40% of the amount of N added through litter. Findings indicate that significant N may be introduced into natural cropping systems through mulching practices and that small changes in practices greatly alter the total inputs. The use of mulch was likely an important source of N in pre-industrial settings and may be used in contemporary systems to reduce nitrogen fertilizer requirements.

Restoring people and productivity to Puanui: challenges and opportunities in the restoration of an intensive rain-fed Hawaiian field system

Prior to European contact, Hawaiian cultivators developed and sustained large rain-fed field systems based on sweet potato (Ipomoea batatas) and other crops. However, these intensive systems largely were abandoned in the 19th century, and there is little knowledge of how they functioned. Since 2008, we have worked to restore people and production to one such rain-fed field system at Puanui in leeward Kohala on the Island of Hawai’i using traditional knowledge, local knowledge, and experiments to understand how such systems functioned and to provide an educational and cultural resource to local communities. We encountered both climatic and biotic challenges to using traditional knowledge for restoring agricultural production. Climatically, there has been a recent drying trend and a severe 6-yr drought. Biotically, a wide range of weeds, pests, and diseases have been introduced to Hawaii since European contact. Experimental studies of cultivation practices demonstrated that rock mulching, a traditional practice, led to significantly greater yields of sweet potato than did alternative methods. More than 3000 students and community members have participated in the restoration effort and have contributed local and traditional knowledge in the process.

Farmer Typology in South Kona, Hawai‘i: Whoʻs Farming, How, and Why?

Abstract Agricultural systems are increasingly being recognized as producing a wide range of benefits and impacts on society, and the potential of small-scale farmers in particular has been highlighted. Recognition of farmers’ varying drivers and priorities is important for developing appropriate policies and engagement strategies to foster multifunctional agricultural practices that generate multiple social benefits from agricultural lands. The use of typologies to classify the diversity of farmers and their respective farming priorities is a practical way to understand important decision-making drivers and capture impacts. This article classifies 128 farmers in the South Kona region of Hawai‘i by assessing their reasons for farming. The types of farmers are discussed regarding their environmental and sense of place values, and an MFA scorecard measuring farming practices in five categories: Environment, Economics, Education, Community, and Culture. Farmer types explained a significant amount of variation seen in each category, suggesting that reason for engaging in farming is an important driver in farming practices; however, significant nuanced variation on value expression in farming practices was apparent.

Sustainable landscape development and value rigidity: the Pirsig‘s monkey trap

New broader, adaptable and accommodating sets of themes have been proposed to help to identify, understand and solve sustainability problems. However, how this knowledge will foster decisions that lead to more desirable outcomes and analyses necessary to transition to sustainability remains a critical theoretical and empirical question for basic and applied research. We argue that we are still underestimating the tendency to lock into certain patterns that come at the cost of the ability to adjust to new situations. This rigidity limits the ability of persons, groups, and companies to respond to new problems, and can make it hard to learn new facts because we pre-select facts as important, or not, in line with our established values. Changing circumstances demand to reappraise values like in the case of Pirsigs monkey and its rice. There is an urgent need to go beyond such local, static and short-term conceptions, where landscape sustainability has been incorrectly envisioned as a durable, stable condition that, once achieved, could persist for generations. We argue that to manage a global transition toward more environmentally efficient and, therefore, more sustainable land-use we have to reappraise societal values at the root of overregulation and rigidity.

Stable carbon and nitrogen isotopes in kukui (Aleurites moluccanus) endocarp along rainfall and elevation gradients: Archaeological implications

Stable carbon and nitrogen isotopes are often used to make inferences of past environments and social patterns. We analyze δ 13C and δ 15N values in contemporary kukui (Aleurites moluccanus) endocarp to examine the effects of site environment. Results from across environmental transects on Hawai‘i Island show strong patterns for both stable isotopes. For δ 13C a robust linear relationship with elevation is exhibited, strengthened by the inclusion of rainfall. This relationship breaks down at a minimum threshold of annual rainfall, possible relating to physiological responses to drought. For δ 15N, the only significant relationship observed pertains to substrate age. The endocarp from kukui is one of the most readily identified plant remains in the Pacific archaeological records and is often targeted for radiocarbon dating. We discuss the potential implications of our results regarding ancient climate, inferred diets, and habitat composition.