Ag-tech startup Mafix announced that it has raised $5.4 million in a pre-seed funding round, with proceeds aimed at scaling production of its silicon fertilizer, designed to improve soil and crop health while removing carbon dioxide from the atmosphere.
Mafix said that although there is demand for silicon fertilizers, producers are unable to reliably obtain high-quality supply at a relevant price. The company said that it is meeting that demand with its permanent carbon sequestration fertilizer that has multiple value props for farmers.
Launched in 2026 as a Stanford University spinout by Jade Marcus and Stanford University chemistry professor Dr. Matthew Kanan, Mafix develops mineral-based fertilizers designed to improve crop yields while removing carbon dioxide from the atmosphere. The company uses a mineral conversion process to transform abundant silicate rocks into fast-weathering fertilizers that release nutrients while removing CO₂ through enhanced rock weathering.
According to Mafix, its mineral conversion process overcomes a key barrier to enhanced rock weathering (ERW), a carbon removal approach that uses alkaline rocks to remove CO₂ from the atmosphere. While conventional ERW approaches, which crush and spread common rocks like basalt, are limited by the extremely slow weathering rates of the mineral constituents, Mafix said that its technology converts inert silicate rocks into fast-weathering minerals, enabling carbon removal within a single growing season. When applied as a fertilizer the minerals release nutrients into the soil to support crop yields, while removing CO₂ as stable bicarbonate.
The company added that its production process is also designed to utilize existing cement manufacturing infrastructure, as its drop-in process can run in existing cement kilns, enabling the company to use spare kiln capacity rather than requiring the construction of new production facilities.
Mafix said that the new capital will be used to commercially demonstrate its technology by producing 1,000 tons of the company’s fertilizer as well as to further advance its mineral conversion process for deployment across a broad range of feedstocks and next-generation products, including new applications and markets beyond agriculture.
Jade Marcus, CEO and cofounder of Mafix, said:
“The alkalinity trapped inside silicate rocks is one of the largest untapped resources on the planet. Our breakthrough is releasing it deliberately and quickly, transforming the most abundant rocks on Earth into a fertilizer that feeds crops and permanently removes CO₂ at the same time.”
The funding round was led by Azolla Ventures with participation from Counteract VC, Astera Institute, Plug and Play Ventures, Impact Science Ventures, and a Dutch family office.
Jillian Chase, Principal at Azolla Ventures, said:
“Mafix’s silicon fertilizer is designed to improve soil health and agricultural productivity while delivering a scalable solution for permanent CO₂ removal, addressing two critical global challenges with a single technology. Its use of existing cement infrastructure for manufacturing means it can scale quickly to address farmers’ immediate needs while Jade, Matt and the impressive Mafix team develop additional products via their mineral transformation technology.”
