Project evaluates how healthy pastures can enhance carbon sequestration and storage in the soil

Brazil currently has 165 million hectares of pastures, but around half of this number presents some degree of degradation. Identifying the best alternatives to recover these areas and understanding how this improvement can help the country meet its climate goals is the core of the project Improving pasture management as a nature-based solution for soil carbon sequestration in Brazil. The study is being developed within the scope of the Research Center for Greenhouse Gas Innovation (RCGI), a research center financed by the São Paulo State Research Support Foundation (Fapesp) and Shell.

“In the Paris Agreement, during COP21 [United Nations Conference on Climate Change], in 2015, the country committed, among other measures, to recover 15 million hectares of degraded pastures, which has already happened. However, this is a low number if we consider that around 50 percent of the pastures remain in some degree of degradation”, says agronomist Carlos Eduardo Pellegrino Cerri, project coordinator and professor at the “Luiz de Queiroz” College of Agriculture at the University of São Paulo (ESALQ-USP).

According to the expert, well-managed pastures can sequester and store carbon in the soil. “In the project we want to find out how much this can reach”, explains Cerri. This information, says the researcher, can serve as input for the development of new public policies that encourage the recovery of pastures, for example. Or contribute to the evaluation of existing initiatives, such as the ABC Plan -- Low Carbon Emission Agriculture. Launched in 2010 by the federal government, the proposal seeks to encourage the adoption of sustainable production technologies to reduce greenhouse gas emissions by the agricultural sector in the country.

Various scenarios 

The project began last year and should be completed by 2026. Currently, the team, made up of ten researchers and 20 undergraduate students from various parts of Brazil, as well as consultants from the United States and United Kingdom, is dedicated to field work . “So far we have visited 12 locations in the northeast region, such as the municipality of Limoeiro do Norte, in Ceará. Soon we will head to the states of Rondônia, Mato Grosso and Tocantins”, says Cerri. In total, 47 trips are planned across the country. “We will visit pastures in all Brazilian regions and with varying degrees of conservation.”

According to Cerri, the idea is to discover at least one pair of pastures in each location -- one of them healthy and the other degraded. “The idea is to compare these two situations. From samples from a well-kept pasture, we can know, for example, what is the maximum carbon accumulation possible to obtain in that region with the adoption of good management practices.”

Everywhere, researchers collect samples of soil, greenhouse gases and vegetation. This material then goes to the laboratory to be analyzed. “We evaluate, for example, the amount of carbon stored in that soil sample and how it behaves in depth according to management practice. It’s as if we did a blood test or an X-ray of that sample”, explains Cerri.

After this phase, researchers will apply modeling to jointly evaluate the data collected through the available bibliography and also through the field study. “We are going to test different scenarios on the computer, taking into account the characteristics of each region of Brazil”, says Cerri. “There is no point recommending, for example, a grass that grows in the pampas for a pasture located in the northeast of the country.”

Reduction of methane emissions 

The project is part of the Nature-Based Solutions program (whose acronym in English is NBS, for Nature Based Solutions) from RCGI, also coordinated by Cerri. The initiative encompasses two other projects: Soil carbon sequestration through integrated agricultural systems, headed by Maurício Roberto Cherubin, and Restoration of native vegetation for carbon sequestration -- Restore C, led by Pedro Brancalion - both are professors at ESALQ-USP. “These are projects in connection with the Sustainable Development Goals [SDGs] established by the United Nations,” says Cerri.

The researcher remembers that pastures require constant maintenance, which implies, for example, effective control of weeds and replacement of nutrients. “It is also necessary to keep an eye on the occurrence of erosion processes”, points out Cerri. According to the expert, a considerable part of the degraded pastures in the country is in the hands of owners who are not professionals in the agricultural sector. “In Brazil, there are many cases of people who live in large urban centers and, upon inheriting a property in the interior, decide to create a pasture to demarcate the land, without, however, closely following the creation process”, reports Cerri. “There’s no way around it: without care, the pasture will degrade.”

According to the researcher, in a healthy pasture the cattle herd does not need to travel long distances in search of food. “This way, the cattle do not lose energy and reach slaughter weight in a shorter period. In some cases, this number can reach 22 months, about a year less than the standard. This contributes to reducing methane emissions from livestock farming”, continues Cerri. “Furthermore, with a greater quantity of grasses it is possible to raise the same number of animals in a smaller area, without compromising the quality of the herd. By reducing the pasture area, other crops, such as soybeans, corn and rice, can expand without resorting to deforestation. That’s what I always say: we don’t need to create more pastures in the country, but rather recover those that already exist.”