Introduction
Silicate rock powders (SRPs) applied on farmlands have gained major traction in the last few years as their “enhanced weathering” (EW) constitutes one of the most durable and promising carbon dioxide removal (CDR) technologies globally. Yet, it is important to remember that rock powders have already been used in agriculture for centuries as a means to improve soil health and that there are solid results about their numerous agronomic benefits, especially in regions around the tropics and subtropics.
The potential of the tropics
But why is the biggest potential in the tropics and subtropics? First, high temperatures and precipitation lead to faster dissolution of silicate minerals. Second, the oftentimes acidic soil environments additionally increase dissolution kinetics — that’s the geochemist’s way of saying they dissolve faster. That means tropical soils are in the utmost need of remineralization.
Additionally, typical conventional fertilizers, initially designed for the soils with a high cation exchange capacity (the soil’s capacity to retain and supply important nutrients) of the global North, are often not affordable, accessible, and suitable for highly weathered tropical soils.
A paper written by InPlanet’s Research Lead, Dr. Swoboda confirmed the major potential for silicate rock powders in the tropics. On top of sequestering CO2, finely ground silicate rock powders can increase the yield of major cash crops, improve soil pH, supply macro- and micronutrients, and strengthen plant biotic and abiotic stress resistance. The country with the longest tradition and most rapidly growing expansion of rock powder usage is Brazil, where the “Rochagem” movement has been developing over decades.
The case for Brazil
For InPlanet, it was this unique mixture of soil suitability and agronomic demand combined with the climate and potentials for scalability that led us to invest in ERW in Brazil.
Sugarcane is the most produced crop in the world (on a weight basis), and Brazil is a leader in the long history of producing and exporting this agricultural product. In the following passages, we report significant yield and soil health benefits for sugarcane crops treated with InPlanet’s rock powder.
In 2023, we spread our basalt rock powder on sugarcane fields in São Paulo state, near the area where our headquarters are located in Brazil. The rock powder applied by InPlanet is certified by the Brazilian Ministry of Agriculture (MAPA) for use in agriculture.
On both our experimental plots as well as on the field scale, we found increases in sugarcane growth parameters like plant height, number of internodes, cane length, cane girth, single cane weight, and number of millable canes eleven months after application at carefully chosen application rates of basalt powder. That means that the sugarcane growing in the same plot area compared to the normally fertilized plots where rock powder was not applied had a higher predicted yield. We are producing more food using the same amount of land, and making remarkable progress in reaching sustainable goals.
Directly related and equally important, soil health increased with remarkable increases in macro- and micronutrient content and other parameters. Plants are not only growing in higher volumes, but they are also growing with a higher supply of nutrients that often also benefit the nutritional value of the produce. The results were received with great interest in the local farming community at a field day organized by our team at one of our partner farms.
A more detailed account of the results will soon be published in a peer-reviewed journal. Importantly, these results were only possible through a careful selection of all relevant factors for the usage of rock powder in agriculture, as shown in the diagram below.
Conclusion
Besides carbon sequestration through enhanced weathering, the major benefit of silicate rock powders (SRP) lies in their capability to increase yields and improve soil health. Therefore, the tropics and subtropics are outstanding and are the regions with the biggest global potential. This is confirmed through broad literature reviews, but also through our own primary agronomic data gathered for sugarcane, which show yield increases with carefully chosen application rates of rock powder.
InPlanet´s operations in Brazil are bridging transdisciplinary gaps and catalyzing the potential of rock powders to remove gigatons of CO2 from the atmosphere while regenerating soils in the tropics.
