Nicholas Krueger, Instructor of Agriculture
Instructor Krueger’s areas of expertise are in grazing systems, tropical forages, livestock nutrition, and soil carbon. His research has wide impact: local farming and ranching, environmental and community health.
Posted Aug 1, 2024
Nicholas Krueger is an instructor of agriculture at the College of Agriculture, Forestry, and Natural Resource Management at the University of Hawaiʻi at Hilo. His areas of expertise are in grazing systems, tropical forages, livestock nutrition, and soil carbon.
Krueger is an alumnus of UH Hilo, receiving his bachelor of science in agriculture in 2010. He received his master of science in agronomy from the University of Florida in 2013, and doctor of philosophy in natural resource and environmental management from UH Mānoa in 2021.
As an undergraduate at UH Hilo, the nascent scientist worked as a research professor’s assistant participating in soil collection expeditions throughout Hawaiʻi Island and conducting soil nutrient analyses. He also assisted in controlled greenhouse plant pot studies, and helped plan and develop a mixed legume and grass experimental pasture. Strengthening the university’s community outreach, he helped develop mutually beneficial cooperative programs with local farmers and producers.
While at Mānoa, Krueger was a research assistant where he facilitated a partnership with a local ranch to conduct soil sampling and grazing studies, developed solution-based research programs targeting challenges faced by the Hawaiʻi ranching community, and performed soil analyses for local ranches to identify potential issues with carbon and macronutrients.
Krueger began teaching at UH Hilo in 2019. In 2023, he was awarded the UH Hilo Chancellor’s Award for Excellence in Teaching, an award given annually to an outstanding lecturer or instructor.
- 2023 Chancellor’s Award for Excellence in Teaching goes to UH Hilo agriculturalist and alumnus Nick Krueger (UH Hilo Stories, June 7, 2023)
Soil carbon in Hawaiʻi rangelands
Krueger co-authored a published paper with a research team that investigated the many challenges of Hawaiʻi ranchers — overgrazing, fire, drought, invasive plant species, feral animals, etc. — and presented solutions for well-managed rangelands encompassing food production, livelihoods, watershed services, climate security, soil health, fire risk reduction, biodiversity, and a wide array of cultural values.
The findings of the study suggest that rangelands, as part of “a landscape mosaic,” contribute to social and ecological health and well-being in Hawaiʻi.
Krueger’s contributions to the study are aimed at highlighting how rangelands have huge amounts of organic carbon contained in the soils beneath them, and that good management of rangelands is beneficial to both the environment and producers.
“Up until recently, most folks have thought of Hawaiʻi’s forested areas as being the most rich in soil carbon, but this research helped to show that rangelands can have comparable amounts and should therefore also be appreciated as a generator of ecosystem services,” says Krueger. “Pasture can oftentimes be just as beneficial to the soil as undisturbed ecosystems.”
The authors conclude their study by identifying important knowledge gaps around rangeland ecosystem services and highlighting the need to “recognize rangelands and their stewards as critical partners in achieving key sustainability goals, and in bridging the long-standing production-conservation divide.”
Sugarcane for jet fuel
Currently, Krueger and a graduate student are wrapping up a field study that investigates best management practices for growing sugarcane to be used for jet fuel.
- Field trials underway to study sugarcane production for jet fuel (UH Hilo Stories, March 25, 2021)
The study looks at the growth of certain cultivars of sugarcane for conversion into high-performance jet fuel. Field trials began in early 2021, growing different cultivars of sugarcane at the UH Hilo Agricultural Farm Laboratory in Panaʻewa with support from the U.S. Department of Agriculture’s Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center located in Hilo. The project is also supported by the Joint BioEnergy Institute, one of four U.S. Department of Energy-funded Bioenergy Research Centers based in California.
Krueger says almost all of the South Pacific relies on imported petroleum products, and this research could help alleviate that issue by identifying a crop that could produce fuel, while also supporting farmers in Hawai‘i. Further, he says, the cultivars of energycane used in the study were developed shortly before the fall of sugar in Hawaiʻi, and the best agronomic practices for their most productive growth have not yet been identified.
Krueger coordinated the planting of the field trials. His major responsibilities on the study were field implementation and management, and data collection and analysis. He also analyzed quality components such as the amounts of various fiber fractions and quality of sugar.
“[The field trial looked] at how things, such as fertilization regime and harvest interval, affect total yield of energycane,” says Krueger. Energycane is a term used for sugarcane cultivars that are high in fiber and generally low in sugar.
“This research is exciting because although it may appear to be beating the dead horse of old sugar in Hawai‘i, there are many additional uses for energycane other than raw sugar production,” he says.
Graduate student Brian Rule is writing up the project, and it should be published early next year. Rule, who graduated with a bachelor of science in agriculture with honors in spring of 2022, is now in UH Hilo’s tropical conservation biology and environmental science master’s program where his interests include studying agronomic effects on energycane cultivars biomass for aviation biofuel. Krueger is Rule’s advisor for the UH Hilo graduate program.
Oxalates in kalo
In another research project, Krueger is working on a collaborative project between UH Hilo and Hawaiʻi Community College to tackle an issue with current food systems. Specifically, the team is looking at ways to ferment or process kalo that could make it more nutritional for individuals and communities.
“The issue is that kalo has high levels of oxalates which are associated with kidney disease, so we were looking at ways to lower the amount of oxalates in order to make kalo a more healthy food,” Krueger explains.
Krueger has led a team of five students (three from UH Hilo and two from Hawaiʻi CC) to investigate the cultural significance of kalo, it’s nutritional content, physical means of processing, and fermentative means of processing, along with a survey of farmers and producers involved in either growing or processing kalo.
The project is supported by BioMADE, a nonprofit focusing on innovation in bioindustrial manufacturing.
“We are just now finishing phase one, which was a collection of information, and will hear if we get awarded phase two, which would be wet lab fermentation techniques to reduce oxalate levels in cooked or uncooked taro,” says Krueger.
Teaching and research
In addition to his field trials work and analysis, which often includes his students to give them real-world research experience, Krueger also teaches animal husbandry, agronomy, horticulture, and soil science courses. He works closely with local farmers to arrange student field trips and to gather information regarding current local agricultural issues.
Additionally, he has developed animal welfare protocols for Institutional Animal Case and Use Committee certification for research involving live animals.
After five years in his instructor position, the UH Hilo alumnus will be applying this fall for a promotion to assistant professor. He will then be on track to develop and conduct his own research projects to publish as lead author.
“I’m really looking forward to the opportunity to carry out research as a component of my job,” he says.
By Susan Enright, a public information specialist for the Office of the Chancellor and editor of Keaohou and UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.
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