RCGI researchers want to know whether integrated agricultural systems sequester more carbon than conventional models

Integrated agricultural systems rely on diversity and crop rotation in the same production area. Keeping an eye on these characteristics, researchers from the Research Center for Innovation in Greenhouse Gases (RCGI). investigate whether these broad land use models are capable of sequestering more carbon dioxide (CO2) from the atmosphere compared to the traditional system. “Integrated agricultural systems have great potential to help our country meet the climate commitments made under the Paris Agreement in 2015, and updated at COP 26, the United Nations Conference on Climate Change, held in 2021 in Glasgow, in Scotland. Furthermore, they can also contribute to Brazil producing more food in the coming decades”, points out Maurício Roberto Cherubin, coordinator of the Soil carbon sequestration through integrated agricultural systems project, at RCGI.

According to the researcher, integrated systems are characterized by variety. “In the same area we can have a grain crop at one time of the year, such as soybeans and corn. After harvesting, in the off-season, it is possible to cultivate forage that serves as pasture for the animals, and thus the practice contributes to meat production. Not to mention that in more complex systems, trees can be placed within the crop, which makes it possible, from time to time, to produce wood”, explains Cherubin, who is a professor in the Soil Science department at the “Luiz de Queiroz” College of Agriculture. ” from the University of São Paulo (ESALQ-USP).

Expected to last five years, the RCGI project began in 2021 and will take place in four phases. In the first stage, the researchers surveyed the bibliography available worldwide regarding integrated agricultural systems. “It is curious to note that in Brazil this practice emerged in the last two decades at the hands of producers, who realized that they could profit in financial terms if they used the land more widely”, says Cherubin. “Due to this demand, the production of academic works in the country on the subject began in the 2000s. In the last five years, research began to investigate the environmental contribution of these systems”.

Researchers are currently carrying out the second module of the project, which consists of visiting places in Brazil where this agricultural practice is already underway. According to the expert, it is estimated that integrated agricultural systems currently occupy around 15 million hectares in 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 at the interface from Maranhão, Tocantins, Piauí and Bahia”, reports Cherubin.

Pursuant to the Paris Agreement, in 2015, Brazil committed to expanding the area already existing in the country with integrated systems by 5 million hectares. “It is worth saying that there are several types of integrated systems that can be applied. The most complete of these is crop-livestock-forest integration (ILPF), but there are also formats such as crop-livestock integration (ILP) and the agroforestry system (SAF), for example. And there are no strict rules: several combinations have been used by producers. In the south of the country, for example, instead of cattle, some systems use sheep”, points out Cherubin.

X-ray of the process

In addition to investigating the capture of CO2 by vegetation in integrated agricultural systems, the researchers intend to understand the soil's role in this story. “The 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 soil minerals and keep carbon stabilized for a long time,” says Cherubin. “However, another part of this carbon can be emitted from the soil into the atmosphere in the form of CO2 or methane (CH4), both considered greenhouse gases. Another example is nitrous oxide (N2O), which, despite not containing carbon in its constitution, has an intimate relationship with the C cycle and agriculture. It is a greenhouse gas that has a major impact on global warming. To give you an idea, if CH4 has 28 times more potential to heat the planet than CO2, N2O offers 265 times more risk in this sense”, continues the expert.

To understand how carbon is retained in the soil, as well as quantifying greenhouse gas emissions, 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 particles. molecules. To make this happen, the project will use the Sirius structure, a state-of-the-art particle accelerator that emits this type of light and is located at the National Center for Research in Energy and Materials (CNPEM), in Campinas (SP). “With the participation of CNPEM researchers, we will be able to take an X-ray of the soil to understand how much CO2 the plant captured was stored in the soil and how this carbon was stabilized”, celebrates Cherubin.

In the next step of the project, whose nickname is Ag4C (an acronym in English for “agriculture for carbon”), researchers will apply modeling to evaluate the data collected during the field study. “The idea is to use a series of prediction models to glimpse the potential of other regions in the country based on data that we measure in strategic areas across Brazil”, says Cherubin to conclude: “These numbers can be used by Brazil in international negotiations and also contribute to the definition of public policies in the country aimed at this issue”.