Azolla as a Soil Amendment to Facilitate Carbon Sequestration

This project investigates an innovative strategy for storing carbon dioxide in a way that potentially is both effective and scalable. This research explores the potential of Azolla, a fast-growing aquatic fern, to support long-term carbon storage in soils. Unique among plants for its ability to fertilize itself by fixing nitrogen, Azolla grows rapidly and could serve as a renewable source of organic material that improves soil health while drawing down carbon dioxide from the atmosphere. The project investigates how Azolla-based soil amendments can contribute to climate mitigation by storing carbon, while also examining how these amendments affect soil life, including plants, bacteria, and earthworms. By focusing on a nature-based solution with minimal input requirements, the research aligns with sustainability goals. Additionally, by potentially integrating nutrient recovery from sources such as wastewater, it also supports the principles of a circular economy. The activity will provide significant educational opportunities through a course-based undergraduate research experience, engaging nearly 120 undergraduate students, graduate students, and a postdoctoral fellow. This will strengthen the science, technology, engineering, and mathematics workforce and promote public engagement with climate and environmental science. The technical goal of the research is to evaluate the use of Azolla as a soil amendment for carbon sequestration and to refine and test a new analytical model that predicts how Azolla grows, decomposes, and stores carbon in soil systems. The research team will compare three different Azolla-based amendments—raw Azolla, composted Azolla, and an Azolla-based biogel—across a series of greenhouse tests. These experiments will assess how much carbon is captured, how long it remains stored in the soil, and how each amendment affects soil health. The research will also determine how much phosphorus is required for Azolla cultivation to ensure that the approach remains sustainable and scalable. By combining controlled experiments with mathematical modeling, the project will provide new insights into the potential of fast-growing aquatic plants to serve as effective tools for biological drawdown and storage of atmospheric carbon dioxide. This work advances scientific understanding of ecosystem-based carbon management and contributes to the broader fields of climate resilience and soil ecology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.