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A new study by a US research team at Woods Hole Research Center, a cli­mate change research orga­ni­za­tion in Massachusetts, has revealed that agri­cul­tural prac­tices have changed the car­bon bal­ance of the earth’s soil.

While global warm­ing is pri­mar­ily blamed on increased car­bon diox­ide emis­sions through the burn­ing of fos­sil fuels and defor­esta­tion, this study, Soil car­bon debt of 12,000 years of human land use, pub­lished in Proceedings of the National Academy of Sciences has exam­ined the role of agri­cul­tural prac­tices in cli­mate change.

One of the research aims was to esti­mate the size and spa­tial dis­tri­b­u­tion of car­bon loss from the soil as a step in under­stand­ing whether soil car­bon seques­tra­tion can effec­tively mit­i­gate cli­mate change.

The researchers were able to quan­tify the amount of car­bon lost world­wide from the soil through the use of agri­cul­tural land for grow­ing crops and graz­ing live­stock. They found that this amounts to 133 bil­lion tons of car­bon loss.

The impact of the so-called ​“car­bon debt” on cli­mate change is nearly as much as that of defor­esta­tion, which has con­tributed to the loss of 140 bil­lion tons of car­bon from soil over the same period.

The study’s find­ings also show that the earth has the poten­tial to absorb car­bon and mit­i­gate global warm­ing through the adop­tion of bet­ter agri­cul­tural prac­tices. Such prac­tices could address the cur­rent car­bon debt by allow­ing the soil to nat­u­rally absorb car­bon and keep it from accu­mu­lat­ing in the atmos­phere.

One of the study’s researchers and an asso­ciate sci­en­tist with the Woods Hole Research Center, Jonathan Sanderman, told the Thomson Reuters Foundation that car­bon loss from the soil can be mit­i­gated through ​“bet­ter land stew­ard­ship, more exten­sive ground cover to min­i­mize ero­sion, bet­ter diver­sity of crop rota­tion and no-till farm­ing.”

The researchers were also able to iden­tify hotspots around the globe where car­bon loss is espe­cially sig­nif­i­cant and where tar­geted efforts should be made for soil car­bon restora­tion. They include major crop­ping regions and graz­ing lands in the range­lands of Argentina, south­ern Africa, and Australia.

According to the Intergovernmental Panel on Climate Change’s pol­icy paper on agri­cul­ture and its role in cli­mate change, green­house gas emis­sions can be mit­i­gated through ​“crop and graz­ing land man­age­ment (e.g., improved agro­nomic prac­tices, nutri­ent use, tillage, and residue man­age­ment), restora­tion of organic soils that are drained for crop pro­duc­tion and restora­tion of degraded lands.”

The paper also rec­om­mends the plant­ing of trees to cap­ture and store car­bon, and empha­sizes that soil car­bon seques­tra­tion has the high­est poten­tial to con­tribute to the mit­i­ga­tion of green­house gases.

• Reuters


• Washington Post