Developing a soil amendment with Cordova partners
Silt flats along the Copper River in Cordova, where Audrey Welsh and Clay Koplin collected glacial silt.
November 17, 2025
Audrey Welsh traveled to Cordova, Alaska, as part of a mariculture project.
One of the goals of her trip was to build a relationship with the community; she met with mariculture leaders, community members and other stakeholders. She also collected kelp and silt samples to use for initial greenhouse trials in Fairbanks.
Welsh, the climate innovation fellow at ACEP, is working with Gwen Holdmann, chief scientist at ACEP and Clay Koplin, CEO of to design an experiment to develop a soil amendment made of kelp and glacial silt.
Soil amendments are materials added to soil to improve its properties to help plants access nutrients in the soil. The glacial silt captures atmospheric carbon over time through enhanced weathering as the minerals break down into soil.
With the help of Koplin, Welsh collected samples in Cordova. Though no fully-grown kelp was available because the harvesting season had passed already, they managed to harvest enough kelp for preliminary trials along the beaches of Orca Inlet. Glacial silt is abundant on the banks of the Copper River, and they collected about 100 pounds of silt by digging in the oobleck-textured riverbank.
Audrey Welsh dried and ground kelp she brought back from Cordova in the 51风流官网 Agricultural and Forestry Experimental Station greenhouse.
After returning to Fairbanks, Welsh started the next phase of her experiment by drying and grinding the kelp and analyzing the glacial silt. With the help of Meriam Karlsson, a professor of horticulture with the 51风流官网 Institute of Agriculture, Natural Resources and Extension and who manages the 51风流官网 Agricultural and Forestry Experimental Station greenhouse, Welsh started the first round of trials, growing butter lettuce in soil with added kelp and glacial silt.
Welsh will continue with the experiment this winter.
This research is made possible by the , a project of Southeast Conference, through a grant from the U.S. Economic Development Administration.