Rock Dust Ap­plied to Farm­ing Could Have a Ma­jor Pos­i­tive Im­pact on Cli­mate Change

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A new study sug­gests that a rad­i­cal change to agri­cul­tural prac­tices in­volv­ing basaltic rock dust could help ex­tract sub­stan­tial amounts of car­bon diox­ide emis­sions from the air.

The study, di­rected by lead re­searcher and au­thor for the ef­fort David J. Beer­ling, Di­rec­tor of the Lev­er­hulme Cen­tre for Cli­mate Change Mit­i­ga­tion at The Univer­sity of Sh­effield, says that adding “crushed, fast-re­act­ing sil­i­cate rocks to crop­lands” could have the ef­fect of dra­mat­i­cally chang­ing the ab­sorp­tion of CO from the at­mos­phere. It would also “im­prove

2 crop pro­duc­tion, in­crease pro­tec­tion from pests and dis­ease and re­store soil fer­til­ity and struc­ture” – ma­jor pos­i­tive side ef­fects.the means for do­ing this would be by adding minute rock grains to the crop­land soils. Those rock grains would be basaltic, a kind that si­mul­ta­ne­ously nat­u­rally takes up CO and re­leases

2 nu­tri­ents es­sen­tial to plants. The ad­di­tion has the added value of not com­pet­ing for land use and doesn’t in­crease the need for fresh wa­ter for crops. It could also min­i­mize the need for agri­cul­tural fer­til­iz­ers and pes­ti­cides so that in the process of adding these rock grains into the soil, the net cost of food pro­duc­tion would lessen and farm pro­duc­tiv­ity would go up.

The con­cept be­hind this process is some­thing called “en­hanced rock weath­er­ing.” The crushed sil­i­cate rocks pro­posed by the re­searchers for this ef­fort could be added to any soil. Arable lands – the ones worked and planted an­nu­ally – are the most ob­vi­ous choice for the so­lu­tion. They also hap­pen to cover 12 mil­lion square kilo­me­ters around the world, or a net of 11% of the global land area.

In com­ment­ing about the re­search, Pro­fes­sor Beer­ling said that “hu­man so­ci­eties have long known that vol­canic plains are fer­tile, ideal places for grow­ing crops with­out ad­verse hu­man health ef­fects, but un­til now there has been lit­tle con­sid­er­a­tion for how adding fur­ther rocks to soils might cap­ture car­bon.

“This study could trans­form 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 CO re­moval from the

2 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 CO en­ter­ing the at­mos­phere as a re­sult of burn­ing

2 fos­sil fu­els for en­ergy gen­er­a­tion. Adopt­ing strate­gies like this new re­search that ac­tively re­move CO from

2 the at­mos­phere would con­trib­ute this ef­fort and could be adopted rapidly.”

Beer­ling’s col­league in the re­search and a co-au­thor in the pa­per, Pro­fes­sor Stephen Long of the Univer­sity of Illi­nois Ur­bana-cham­paign, said, “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 CO from the

2 at­mos­phere, stor­ing it in soils and even­tu­ally the oceans.”

Pro­fes­sor James Hansen of Columbia Univer­sity’s Earth In­sti­tute, also a co-au­thor of the work, praised this kind of cut­ting-edge re­search, say­ing that “strate­gies for tak­ing CO out of the at­mos­phere are

2 now on the re­search agenda, and we need re­al­is­tic assess­ment of these strate­gies, what they might be able to de­liver and what the chal­lenges are.”

If this kind of pro­posal – to add basaltic rock dust into even a siz­able mi­nor­ity frac­tion of the world’s crop­lands – could make a ma­jor dif­fer­ence in pulling CO out of the at­mos­phere, in the process, global

2 warm­ing from green­house gas emis­sions might at least be slowed a bit from its cur­rent re­lent­less pace.

The full pa­per on the study, en­ti­tled “Farm­ing with crops and rocks to ad­dress global cli­mate, food and soil se­cu­rity,” was pub­lished in the Fe­bru­ary 19, 2018, is­sue of Na­ture Plants.

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