In olive groves, cover crops reduce carbon loss by 76%

indingsUniversity of Córdoba study: use of these crops reduces soil carbon loss in Mediterranean olive groves by more than 75 percent

by Matteo Cavallito

 

The use of cover crops can drastically reduce organic carbon loss in some soils in the Mediterranean region. This was revealed in a study by the University of Córdoba, Spain.

The investigation focused on olive groves that, the researchers note in a statement released by the same university, “feature high erosion rates due to a perfect storm: a climate with episodes of intense rainfall, the orography of many mountain olive groves, with steep slopes; and conventional tillage.” This practice, in particular, “leaves the soil bare, leading to runoff, soil creep, and, with it, losses of the organic carbon associated with sediment.”

Eight plantations under investigation

The team of scientists, coordinated by Francisco Márquez, a researcher in the AGR 126 “Rural Mechanization and Technology” research group at the University of Córdoba, analyzed, over a four-year period, the effects of ground cover on organic carbon loss. Findings were compared with those found in fields subject to conventional tillage.

Operating in some of the main olive-growing areas of Andalusia, the researchers examined “8 plantations in the main olive-growing regions, with diverse soils, different types of olive groves (traditional, mountain and intensive), and with almost all types of ground cover,” Márquez explains.

The scientists were thus able to evaluate the influence of these factors as well, coming to a clear conclusion: “We concluded that ground cover not only reduces erosion and runoff, but also losses of organic carbon in soil, by three quarters compared to tillage.”

Crops reduce losses by 76 percent

In the observed soils, land cover “was responsible for a 36.7 % average reduction in runoff and an 85.5 % reduction in erosion compared to tillage,” the study says. The practice also “decreased SOC loss associated with sediment by 76.4 %”. Moreover, during rainfalls, “Conversely to tillage where only 22.4 % of soil was protected, scover crops provided a 65.7 % cover throughout the season.”

The explanation for the phenomenon is quite simple: cover strengthens the structure and cohesion of soil particles.

Doing so drastically limits erosion and carbon release with a couple of benefits: the increased soil fertility and the reduction of carbon emissions with resulting mitigation of climate change.

Carbon farming is crucial

The implications of the study are particularly relevant for a region like the Mediterranean where olive cultivation is extremely widespread and the combination of several factors creates critical situations. “The majority of the plantations are on rainfed land, poor soils with steep slopes,” the study explains. “ARegarding to soil, tillage is the main management system used by farmers. Consequently, erosion and the resulting soil organic carbon losses associated to it are one of the main environmental problems of olive production.”

Within this framework, the adoption of cover crops takes on a crucial role as part of carbon farming initiatives. That is, according to the European Commission’s definition, “agricultural practices that help to capture carbon from the atmosphere and store it in soil or biomass.” Applying these strategies, in other words, means achieving more sustainable and profitable crops that can effectively combat climate change.