Mafix Raises $5.4M to Test Silicon Fertilizer at Commercial Scale

Mafix has raised $5.4 million in pre-seed funding to commercialize a silicon fertilizer designed to support crop performance while accelerating the natural process that removes carbon dioxide through rock weathering.

Azolla Ventures led the round. Counteract VC, Astera Institute, Plug and Play Ventures, Impact Science Ventures, and an undisclosed Dutch family office also participated.

The company was founded by CEO Jade Marcus and Stanford chemistry professor Matthew Kanan. Its mineral-conversion process grew out of research developed at Stanford University.

One product, two economic questions

Mafix sits between agriculture and carbon removal. That is the opportunity and the burden.

Silicon can help some crops manage environmental stress, but naturally occurring silicate minerals often weather too slowly to deliver plant-available silicon on an agricultural timeline. Mafix says its process converts silicate rock into a material capable of weathering within a growing season. The product is designed to be applied with existing farm equipment.

As that material weathers, it is also intended to accelerate a carbon-removal pathway known as enhanced rock weathering. The business model depends on connecting the agronomic value of the fertilizer to the carbon value of the chemical reaction.

Neither side should be treated as proven at commercial scale yet. Farmers will care about field performance, handling, consistency, and price. Carbon buyers will care about measurement, permanence, additionality, and whether the removal can be verified without consuming the economics.

Using industrial capacity that already exists

Mafix plans to produce its material using spare cement-kiln capacity rather than financing a dedicated first-of-kind manufacturing facility. The company says roughly 30% of global kiln capacity is idle.

That choice could shorten the route to production, but it also places execution inside someone else's industrial environment. Feedstock quality, process controls, logistics, emissions accounting, and the economics of contract manufacturing will all matter as volumes increase.

The new capital will support larger field trials and a commercial demonstration expected to produce at least 1,000 tons of material.

What the pre-seed round has to prove

Mafix is not raising to discover whether farmers and carbon markets sound compatible in a presentation. It is raising to learn whether one product can carry both value propositions through the field, the kiln, the supply chain, and the measurement process.

If fertilizer economics can support the early deployment, carbon revenue may improve the model. If the agronomic benefit is inconsistent or the verification burden is too expensive, the second half of the thesis will have less room to help.

The $5.4 million buys Mafix a commercial-scale test of the relationship. The result will be written in crop data, production yields, farmer economics, and the quality of the carbon record left behind.