Farming crops with crushed rocks could help to improve global food security and reduce the amount of CO2 entering the atmosphere, a new study has found.
The research, by scientists at the University of Sheffield, suggests that adding fast-reacting silicate rocks to croplands could capture CO2 and give increased protection from pests and diseases while restoring soil structure and fertility.
Minute rock grains added to crops dissolve chemically in soils taking up carbon dioxide and release plant-essential nutrients, the study shows.
It says that unlike other carbon removal strategies, enhanced rock weathering doesn’t compete for land used to grow food or increase the demand for freshwater.
Professor David Beerling at the University of Sheffield and lead author of the research, said: “Human societies have long known that volcanic plains are fertile, ideal places for growing crops without adverse human health effects.”
But he said that until now, there has been "little consideration" for how adding further rocks to soils might capture carbon.
He added: “This study has transformed how we think about managing our croplands for climate, food and soil security. It helps move the debate forward for an under-researched strategy of CO2 removal from the atmosphere - enhanced rock weathering - and highlights supplementary benefits for food and soils.
“The magnitude of future climate change could be moderated by immediately reducing the amount of CO2 entering the atmosphere as a result of energy generation. Adopting strategies like this new research that actively remove CO2 from it can have a massive impact and be adapted very quickly.”
Lowering costs
The research, published in Nature Plants, examined the approach which involves amending soils with abundant crushed silicate rocks, like basalt, left over from ancient volcanic eruptions.
Critically, enhanced rock weathering works together with existing managed croplands.
Other benefits include reducing the usage of agricultural fertilisers and pesticides, lowering the cost of food production, increasing the profitability of farms and reducing the barriers to uptake by the agricultural sector.
The study shows that crushed silicate rocks could be applied to any soils, but arable land is the most obvious since it is worked and planted annually.
It covers some 14 million square kilometres or 10 per cent of the global land area.
Acidification
Arable farms already apply crushed rock in the form of limestone to reverse acidification of soils caused by farming practices, including the use of fertilisers.
Managed crops, therefore, have the logistical infrastructure such as the road networks and machinery needed to undertake this approach at scale. The research shows that these considerations could make it straight forward to adopt.
Professor Stephen Long at the University of Illinois Champaign-Urbana, and co-author of the study added: “Our proposal is that changing the type of rock, and increasing the application rate, would do the same job as applying crushed limestone but help capture CO2 from the atmosphere, storing it in soils and eventually the oceans.
“Global warming is a problem that affects everyone on the planet. Scientists generally have done a poor job of getting across the point that the world must reduce emissions of greenhouse gases from fossil fuels and combine this with strategies for extracting carbon dioxide from the atmosphere to avoid a climate catastrophe.”
