22 April 2022

3 min read

Olive soil is emerging as a great ally against climate change

It has been demonstrated that soil is one of the largest reservoirs of carbon in terrestrial ecosystems, since in the process of CO2 sequestration, it contributes greatly to reducing greenhouse gases.

The doctoral thesis of the researcher of the Department of Agricultural Chemistry, Soil Science and Microbiology of the University of Cordoba, who works within the European project Diverfarming Manuel González Rosado, is based on this premise.

As the doctor in Soil Science and Agricultural Chemistry explains, the soil of the Mediterranean olive grove has an enormous capacity to sequester carbon because, for many years, bad practices have been used that have led to the loss of CO2, such as conventional tillage or no tillage based on herbicides. This has led to the fact that very little stabilized carbon has been found in the soil in the plots in Jaén where the study has been carried out, so there is currently a large storage capacity in this area. “These are soils that have great potential, because there is a lot of storage availability, which gives the opportunity to sequester carbon and make it remain, with the right agricultural practices,” explains González.

For this reason, González Rosado considers almost “mandatory” a change of management that involves the inclusion of vegetation covers, which also increase productivity and promote the regeneration of soil properties, improving them. At the opposite extreme, he points out that conventional tillage and no-tillage practices with bare soil are unsustainable to achieve objectives such as those of the “4 per 1,000” initiative, which proposes an increase in soil carbon of 0.4% in the first 40 cm of soil.

But his thesis goes further, studying not only this upper layer but also the other soil strata. In this way, he considers it very relevant to take into account the deep horizon in carbon storage because the effects vary. “We analyzed complete profiles up to 120 cm deep and we saw that almost 50% of carbon was stored in these lower layers”, explains the researcher, indicating that if only the first 40 cm had been taken into account “the changes would not have been significant”. In fact, the result varies even within the same plot, depending on the depth to which one refers.

For this reason, it is important to study the way in which carbon is not only stored, but also the way in which it is maintained at depth, since depending on the fraction of the soil in which the carbon is found, it will have greater or lesser stability.