Carbon-Capturing Power of Olive Groves Measured

Summary

The Spanish C‑Olivar project has shown that 15 olive grove plots in Estepa sequester 412 met­ric tons of car­bon diox­ide equiv­a­lent per year, with vary­ing man­age­ment prac­tices affect­ing car­bon stor­age lev­els. The project aims to increase car­bon seques­tra­tion in olive groves by devel­op­ing method­olo­gies for cal­cu­lat­ing car­bon cred­its, cre­at­ing a vol­un­tary car­bon credit mar­ket, and pro­mot­ing prac­tices that favor car­bon seques­tra­tion.

The first results of the Spanish C‑Olivar project have been pub­lished, show­ing that the 15 plots stud­ied achieve a net seques­tra­tion of 412 met­ric tons of car­bon diox­ide equiv­a­lent per annum. 

The plots, located in Estepa, Andalusia, com­prised 440 hectares of olive groves with vary­ing man­age­ment prac­tices.

C‑Olivar is an oper­a­tional group based in Andalusia com­pris­ing regional and national gov­ern­ment agen­cies, the University of Jaén, the agri­cul­tural pro­fes­sion­als’ orga­ni­za­tion ASAJA-Sevilla, the Estepa Protected Designation of Origin (PDO) reg­u­la­tory body, and Evenor-Tech, a tech­nol­ogy com­pany spe­cial­iz­ing in land man­age­ment and envi­ron­men­tal pro­tec­tion.

The pri­mary objec­tive of the project is to increase the amount of car­bon stored by olive groves. To achieve this, the group is tasked with devis­ing a method­ol­ogy for cal­cu­lat­ing car­bon cred­its for olive grow­ers, cre­at­ing a vol­un­tary car­bon credit mar­ket for the sec­tor, increas­ing the adop­tion of olive cul­ti­va­tion prac­tices that favor car­bon seques­tra­tion and devel­op­ing tech­nol­ogy to assist farm­ers and tech­ni­cians in this endeavor.

The analy­sis eval­u­ated the car­bon stored in the per­ma­nent struc­tures of the olive trees and in the soil, reveal­ing seques­tra­tion ranges of between 0.6 and 2.6 tons of car­bon diox­ide equiv­a­lent per hectare per annum for trees. 

In six of the 15 plots, addi­tional seques­tra­tion of 0.36 to 2.1 tons per hectare was observed in the soil, while in the remain­ing nine plots, a loss of soil car­bon was recorded.

In those plots for which a soil car­bon loss was reported, dif­fer­ences in man­age­ment prac­tices were pri­mar­ily deemed respon­si­ble. These included sparse or absent ground cover and the lack of organic soil con­di­tion­ing tech­niques.

Previous research has shown that tra­di­tion­ally man­aged olive groves store sig­nif­i­cantly more car­bon, and that both ground cover and organic soil con­di­tion­ing are major con­tribut­ing fac­tors.

“The appli­ca­tion of organic fer­til­iz­ers and facil­i­tat­ing tem­po­rary spon­ta­neous cover crops achieve a pos­i­tive car­bon bal­ance and reduce the neg­a­tive impacts of olive cul­ti­va­tion,” said Lázuli Fernández from the University of Jaén.

“[Traditional olive groves] allow 5.5 kilo­grams of car­bon diox­ide equiv­a­lent to be removed from the atmos­phere for each kilo­gram of [unpack­aged] oil pro­duced,” she added. ​“In the case of irri­gated cul­ti­va­tion, this value drops to 4.3, and the inten­sive method allows cap­tur­ing up to 2.7 kilo­grams of car­bon diox­ide equiv­a­lent for one kilo­gram of oil.”

In five of the nine plots for which a soil car­bon loss was reported, the car­bon accu­mu­lated in the trees bal­anced the loss from the soil. In the remain­ing four, a net car­bon emis­sion was recorded. This again was attrib­uted to man­age­ment prac­tices.

There are approx­i­mately 11.7 mil­lion hectares of land ded­i­cated to olive cul­ti­va­tion world­wide, an area roughly equiv­a­lent to the size of Portugal. 

If the results from the C‑Olivar analy­sis were found to be rep­re­sen­ta­tive, includ­ing those plots with a net emis­sion, this would equate to approx­i­mately 10.96 mil­lion tons of car­bon diox­ide equiv­a­lent sequestered per annum.

In their press release, how­ever, the Seville chap­ter of the Association of Young Farmers and Ranchers (ASAJA-Sevilla) empha­sized the need to improve farm­ing prac­tices to increase car­bon seques­tra­tion, a key project goal. 

If the high­est fig­ures from the plots in the study area were repli­cated, this would raise the global olive grove car­bon stor­age to approx­i­mately 55 mil­lion tons per year.

“From the Estepa PDO, we con­tinue to work stead­fastly to obtain rig­or­ous data that high­light the essen­tial role played by our olive groves as a car­bon sink and their abil­ity to mit­i­gate the effects of cli­mate change,” said Moisés Caballero, sec­re­tary-gen­eral of the Estepa PDO.

“This research is another exam­ple of the envi­ron­men­tal poten­tial of olive cul­ti­va­tion and encour­ages us to con­tinue our com­mit­ment to a sus­tain­able agri­cul­tural model that is com­mit­ted to the future of the planet,” he con­cluded.

• ASAJA Seville