Legacy carbon sequestration in northern agricultural soils through optimized fertilizer management
Research-driven insights into how fertilizer rate and type affect decomposition of legacy soil carbon in northern agricultural fields. This work helps agricultural producers and policymakers develop nutrient management strategies that preserve long-stored soil carbon while maintaining crop productivity.
Overview
Northern agricultural soils store significant amounts of legacy carbon—organic matter accumulated under natural forest or grassland ecosystems before agricultural conversion. This research investigates how nitrogen fertilizer application rate and form influence the decomposition and loss of this legacy carbon pool. Findings support the development of evidence-based fertilizer management practices that protect long-term soil carbon stocks in boreal and sub-arctic agricultural systems.
Technical specifications
Research approach:
- Laboratory incubation of soils from northern agricultural fields in Alaska and Canada with known conversion histories
- Six levels of nitrogen addition crossed with two fertilizer types (organic and inorganic)
- Continuous monitoring of soil respiration to estimate cumulative carbon loss over a three-month incubation period
- Radiocarbon age measurement of respired carbon at two time points during incubation to track decomposition of older versus newer carbon pools
- Measurement of initial soil carbon pools, their ages, and decomposability indices
Key findings to date:
- Inorganic fertilizer addition stimulates soil carbon decomposition and increases the age of respired carbon
- Both soil respiration per unit soil carbon and the age of respired soil carbon are higher in fertilized treatments compared to controls
- Field fertilizer additions to plant-soil systems show results consistent with laboratory findings
Technology readiness level
The hypothesis has been validated through a two-level laboratory and field experiment demonstrating that nitrogen fertilizer destabilizes old carbon. The current proposed study extends this work by systematically examining fertilizer rate and form effects across multiple northern agricultural sites. This is an active research program at the validation stage, with results intended to inform nutrient management recommendations and carbon accounting frameworks for northern agricultural systems.
About Northern Arizona University
Northern Arizona University is a comprehensive public research university in Flagstaff with an applied, partnership-oriented culture. Interdisciplinary labs and an applied R&D complex are co-located on campus to facilitate prototyping, testing, and joint work with companies. The university engages closely with the region’s innovation ecosystem—collaborating with incubators, municipal partners, and healthcare providers—to connect corporate R&D teams with faculty expertise and student talent. Research is supported by competitive federal funding from agencies such as the NSF, NIH, DOE, and NASA. A dedicated technology transfer office provides IP management, licensing, and startup support to accelerate commercialization.
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