Managing the climate and food supply together by amending cropland with crushed rock

Investigations into the hitherto little-studied carbon dioxide mitigation technique of enhanced rock weathering have uncovered its startling synergy with crop soil amendment. The infusion of crushed silicate rock into farmland bolsters soil quality and crop productivity in addition to removing carbon dioxide pollution from the air, as detailed by researchers who published their findings in Nature Plants.

• The soil of volcanic plains is rich in crushed basalt and other types of silicate rocks. These areas are historically acknowledged as fertile croplands fit for human use.
• Crushed limestone has been used in soil amendment of acidic farmland exposed to excessive amounts of artificial fertilizer. The acidification process is reversed and the treated soil eventually regains fertility.
• The research team modified the above procedure by using large amounts of crushed silicate rock. As they dissolve in the soil, silica grains absorb carbon dioxide and release beneficial nutrients critical to plant growth.
• Soil amendment using crushed silicate rock has been confirmed to absorb carbon dioxide from the atmosphere. Furthermore, it also improves the structure and fertility of soil while also offering a measure of protection against insects and diseases.
• Enhanced rock weathering is highly compatible with cropland as they complement each other instead of competing for available land and freshwater supplies. Arable land has the requisite manpower availability and logistical infrastructure to implement this modified method of soil amendment on a massive scale.

The researchers propose the adoption of enhanced rock weathering in as much of the 8.7 million square miles (14 million square kilometers) of the world’s arable land as possible. Such a large-scale soil amendment could simultaneously reduce global levels of carbon dioxide and improve the world’s food supplies.

Journal reference:

Beerling DJ, Leake JR, Long SP, Scholes JD, Ton J, Nelson PN, Bird M, Kantzas E, Taylor LL, Sarkar B, et al. FARMING WITH CROPS AND ROCKS TO ADDRESS GLOBAL CLIMATE, FOOD AND SOIL SECURITY. Nature Plants. 19 February 2018;4(3):138–147. DOI: 10.1038/s41477-018-0108-y