The XPRIZE winner has signed a five-year agreement with CGIAR researchers to run independent enhanced rock weathering field trials on smallholder farms across tropical regions, where the evidence base is thinnest.
Mati Carbon, which won the XPRIZE carbon removal grand prize, has signed a global memorandum of understanding with the Alliance of Bioversity International and the International Center for Tropical Agriculture, known as CIAT. Both sit within CGIAR. The five-year agreement covers trial design, data sharing, publication and joint fundraising.
Enhanced rock weathering spreads crushed silicate rock, usually basalt, across farmland. As the rock breaks down it reacts with carbon dioxide dissolved in soil water, holding the carbon as stable bicarbonate that eventually reaches the ocean. The same chemistry raises soil pH, which is why the technique is often sold to farmers as a soil treatment as well as a removal method.
Why tropical soils are the open question
Most of the evidence for the technique comes from temperate commercial agriculture. Tropical soils behave differently, being older, more acidic and more weathered. In principle they should give the strongest agronomic response, though that has yet to be shown at scale under working farm conditions.
The gap matters for credit pricing. Buyers pay for durable removal, and durability claims in enhanced rock weathering rest on field measurement rather than laboratory chemistry. Without tropical field data, projects in those regions carry a measurement discount that shows up directly in the price a tonne fetches.
Independent replication is the point
Mati says its team recorded a median yield increase of about 25% across 235 paired plots in India after spreading crushed basalt. Results of that kind need independent replication before an extension service, a ministry or a farmer organisation can act on them.
Dr Wanjiru Kamau-Rutenberg, managing director for Africa at the Alliance of Bioversity International and CIAT, said: “Our role is to generate independent, published evidence under the real-world conditions in which smallholder farmers operate.”
She added: “By working with farmers and national partners across tropical regions, we can determine where enhanced rock weathering delivers agronomic and climate benefits, where it does not, and what would be required for responsible scaling.”
What the trials will measure
The Alliance will lead the design and analysis. The trials will assess whether crushed basalt can be recommended responsibly across the range of tropical smallholder systems, crops and agroecological conditions in which the Alliance and its partners work.
Findings will be published whether or not the Alliance ends up favouring the practice. That commitment is the substance of the agreement, because a negative result published by an independent agricultural research body would carry as much weight with buyers as a positive one.
