The study is underway in various regions of Brazil, including the use of techniques varying from the molecular scale, such as synchrotron radiation, to the national scale via the use of scenario models and analyses.
Integrated agricultural systems rely on the diversity and rotation of crops within the same production area. Focusing on these characteristics, researchers from the Research Centre for Greenhouse Gas Innovation (RCGI) – FAPESP/Shell are investigating whether these land-use models are capable of sequestering more carbon dioxide (CO2) from the atmosphere than the traditional systems. “Integrated agricultural systems have great potential for helping our country meet the climate commitments signed under the Paris Agreement in 2015 and updated at COP 26 (the United Nations Conference on Climate Change) held in 2021 in Glasgow, Scotland. They can also help Brazil produce more food in the coming decades,” points out Maurício Roberto Cherubin, Coordinator of the RCGI’s Soil Carbon Sequestration through Integrated Agricultural Systems project.
Cherubin, who is a professor in the Department of Soil Science of the “Luiz de Queiroz” College of Agriculture of the University of São Paulo (ESALQ-USP), states that integrated systems are characterized by their variety. “In the same area, at one time of the year, we can grow such grains as soybeans and corn. After harvesting, in the off-season, it is possible to cultivate a pasture that serves as grazing land for animals, and this practice contributes to the production of meat. Not to mention that in more complex systems, trees can be planted with the crop, which makes it possible, from time to time, to harvest wood.”
With an expected duration of five years, the RCGI project started in 2021 and is being carried out in four phases. In the first phase, the researchers gathered a bibliography of the available integrated agricultural systems, worldwide. “It is interesting to note that this practice emerged in Brazil over the last two decades in the hands of producers who realized they could profit financially, if they made better use of the land on a broader scale,” says Cherubin. “Because of that demand, academic literature production on the subject in Brazil began in the first decades of the millennium. In the last five years, research began to investigate the environmental contribution of these systems.”
The researchers are currently working with the second module of the project, which consists of visiting places in Brazil where this agricultural practice is already underway. According to Cherubin, it is estimated that integrated agricultural systems currently occupy around 15 million hectares throughout the country – an area equivalent to five times the size of Belgium. “This procedure has been adopted in practically all Brazilian states, but especially in Mato Grosso, Mato Grosso do Sul, São Paulo, Paraná, Rio Grande do Sul, and in the region known as Matopiba, one of the largest agricultural frontiers in the world located within the area where the borders of the states of Maranhão, Tocantins, Piauí, and Bahia meet,” says Cherubin.
As a result of the Paris Agreement, in 2015, Brazil committed to expanding the existing area in the country by five million hectares with integrated systems. “It is worthy of note that several types of integrated systems can be applied there. The most complete type is crop-livestock-forest integration system (CLFI), but there are also such formats as crop-livestock integration system (CLI), and agroforestry systems (AFS). And there are no rigid rules: different combinations have been used by producers. In the south of the country, for example, instead of cattle, some systems use sheep,” Cherubin points out.
A closer look at the process – In addition to investigating the capture of CO2 by the vegetation of integrated agricultural systems, the researchers want to understand the role of the soil in this story. “Carbon dioxide captured by plants is transformed by soil organisms. Part of it is accumulated in the soil in the form of various organic compounds. Some of these compounds bind to minerals in the soil and keep the carbon stabilized for a long time,” says Cherubin. And he continues, “However, another part of this carbon can be released from the soil into the atmosphere in the form of CO2 or methane (CH4), both of which are greenhouse gases. Another example is nitrous oxide (N2O), which, despite containing no carbon, is closely related to the C cycle and to agriculture. It is a greenhouse gas with a major impact on global warming. Just to give perspective to this, if CH4 has 28 times more potential to warm the planet than CO2, N2O offers 265 times more risk in this regard.”
In order to understand how carbon is retained in the soil, as well as to quantify greenhouse gas emissions, the researchers will use techniques based on synchrotron radiation, a special type of light that allows investigating the structure of matter on the scale of atoms and molecules. For this to take place, the project will use the structure of Sirius, a state-of-the-art particle accelerator that emits this type of light and is located in the National Center for Research in Energy and Materials (CNPEM), in the city of Campinas, in outstate São Paulo. “With the participation of CNPEM researchers, we will be able to take deeper look at the soil to understand how much of the CO2 captured by the plant was stored in the soil and in what manner that carbon was stabilized,” Cherubin says enthusiastically.
In the next step of the project, nicknamed Ag4C (“agriculture for carbon”), the researchers will use modeling to evaluate the data collected during the field study. “The plan is to use a series of prediction models to envision the potential of other regions in the country, based on data that we measure in strategic areas across Brazil,” says Cherubin, and he concludes: “These numbers can be used by Brazil in international negotiations and can also contribute to the establishment of the country’s public policies focused on this issue.”