Farming with crops and rocks to address global climate, food and soil security

Abstract

The magnitude of future climate change could be moderated by immediately reducing the amount of CO entering the atmosphere as a result of energy generation and by adopting strategies that actively remove CO from it. Biogeochemical improvement of soils by adding crushed, fast-reacting silicate rocks to croplands is one such CO-removal strategy. This approach has the potential to improve crop production, increase protection from pests and diseases, and restore soil fertility and structure. Managed croplands worldwide are already equipped for frequent rock dust additions to soils, making rapid adoption at scale feasible, and the potential benefits could generate financial incentives for widespread adoption in the agricultural sector. However, there are still obstacles to be surmounted. Audited field-scale assessments of the efficacy of CO capture are urgently required together with detailed environmental monitoring. A cost-effective way to meet the rock requirements for CO removal must be found, possibly involving the recycling of silicate waste materials. Finally, issues of public perception, trust and acceptance must also be addressed.

Managing for soil carbon sequestration: Let’s get realistic

“…Another recent suggestion is to add ground silicate minerals to soils to stimulate carbon sequestration via chemical weathering (Beerling et al, ), viz.…”

“…Globally, silicate weathering removes 0.2–0.3 Pg C/year (Hilley & Porder, ; Suchet & Probst, ) an equivalent of 2.5% of fossil fuel CO 2 emissions to the atmosphere annually. Doubling this rate by adding ground silicate rock to all soils of the world, discounted by up to 30% to account for the CO 2 emitted during the mining, crushing, and transport of silicate rock (Beerling et al, , cf. Moosdorf, Renforth, & Hartman, ), would provide an incremental sink for about 2% of global fossil fuel emissions.…”

Characterising the biophysical, economic and social impacts of soil carbon sequestration as a greenhouse gas removal technology

“…These measures employ inorganic resources to modify soil properties, serving either to improve nutrient availability to crops, increase primary productivity or reduce the likelihood of CO 2 release to the atmosphere via microbial mineralisation. Mineral carbonation stands distinct from all other measures assessed in this study in that it provides a permanent soil‐based sink for mineralised organic C (Beerling et al, ).…”

“…Purchase of material comminuted to maximise GGR is required, ad application may incur time costs (Renforth, 2012). Rigorous determinations of yield benefits of crushed basaltic rocks are few (Beerling et al, 2018), but recent studies show some successes (e.g. de Fátima Tavares, Carvalho, Camargo, Fátima Pereira, & Cardoso, 2018).…”

“…Risk of yield non-response or health impacts may disincentivise uptake (Pidgeon & Spence, 2017). Lack of a broad research base may present a knowledge barrier (Beerling et al, 2018). Global application depends on the ability to source calcium-bearing silicate rocks and to deliver these in appropriate form to farms for application.…”