Rock Powder with Biochar: Synergies & Co-Benefits

Rock powder and Biochar are two of the most powerful tools for reversing climate change, especially when used together! Tom Goreau explains the synergies and co-benefits. (Originally published by Global Carbon Alliance.)

Dr. Thomas J. F. Goreau

Biochar and rock powders can provide major, cost-effective, atmospheric CO2 sinks to reverse climate change through nature-based solutions, or planetary BioGeoTherapy.

These methods produce major synergies and co-benefits when practiced together, but the benefits of each method have been measured in isolation, without positive feedback from combination.

The most effective use of each material is mixed together with the other in order to maximize synergies and co-benefits for increasing land productivity and reversing climate change!

Biochar is a carbon store that holds water and nutrients, but those must be added to it, so rock powders plus compost are perfect complements. Raw Biochar is ineffective (see graph below).

Biochar/rock powder mixtures increase root growth and increase the release of underground respiratory CO2 and organic acids, which further accelerate rock powder weathering that releases essential nutrients, which Biochar stores and makes available to plants (Biochar does hold much bicarbonate).

Raw Biochar (red dots) harms plants, mature biochar mixed with rock powder and compost (blue dots) benefits them! From T. Goreau, 2017, Regenerative development to reverse climate change: Quantity and quality of soil carbon sequestration control rates of CO2 and climate stabilization at safe levels, p. 286-291, Proceedings of the FAO Global Symposium on Soil Organic Carbon, Rome

Biochar and rock powder combinations increase both the rate at which climate and fertilization benefits occur and the duration of those benefits–for both plant nutrition and carbon removal–by recycling carbon and nutrients to accelerate production, biomass, biodiversity, and ecosystem services.

The basic rock weathering chemical reaction is:

CO2 + rock minerals = bicarbonate anion + Cations (+ silica unless mineral is limestone).

Short-term temporary intermediate sinks (such as bicarbonate dissolved in soil water) are often mistakenly called “carbon sequestration”, confusing net and gross fluxes and carbon storage.

Biochar carbon will remain in the soil for a very long time, but bicarbonate will not be stored in soil unless climate is so dry that limestone nodules (caliche) precipitate out of soil solutions.

Bicarbonate, cations, and silica are dissolved and ultimately flushed into groundwater, rivers, and into the sea, which accumulates bicarbonate until the carbon is removed biologically and stored as sediment organic carbon and limestone, which are the long-term sinks.

Rock powder and Biochar used together minimize nutrient and soil loss and maximize Geotherapy benefits to people and planet!

Tom Goreau is President of the Global Coral Reef Alliance, a non-profit organization for coral reef protection and sustainable management, and Coordinator of the United Nations Commission on Sustainable Development Partnership in New Technologies for Small Island Developing States. He works with tropical fishing communities and organizations around the world to restore their coral reefs and fisheries. He is also a trained nuisance crocodile remover who would rather not. Dr. Goreau is the researcher for Remineralize the Earth’s New Harmony Farm CSA Research Project. He is working to determine optimal ratios of rock dust, biochar and compost for use in agriculture, to create foods with high nutrient density and maximum carbon sequestration. He did a significant study on remineralization showing more than eight times the biomass for trees grown in Panama with basalt rock dust over a five-year period, and showing increases in major macro and mico-nutrients. He is the main editor and co-author of Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase, a technical book on remineralization and biochar, to be published in 2014 by CRC Press.