Crop-livestock integration boosts profitability and reduces emissions

The results of a project involving Brazilian and British researchers show that integrated crop-livestock-pasture systems improve soil quality, increase cattle yields and benefit the environment.

By André Julião  |  Agência FAPESP – Fazenda Campina, a farm in Caiuá, São Paulo State, owned by the Carlos Viacava Group, one of Brazil’s leading producers of hornless Nelore cattle (Bos indicus), has implemented a system that integrates livestock and cereal grain production.

The group specializes in the production of dams, which are highly selected cows sold to breeders. The group is in the process of reducing the proportion of its farms occupied by cattle and increasing the proportion used to grow grain crops.

Occupancy by cattle has fallen from 97% to 50% since 2012, but the profit earned from livestock production has risen. The other 50% is used to grow corn, sorghum, pigeon pea (Cajanus cajan), and, above all, soybeans.

According to the producers, crop-livestock-pasture integration has enriched the soil so much that the cattle express their genes more efficiently. In addition, dams are fertile after only 14 months, compared with a national average of 24 months in Brazil, and produce more offspring during their lifetimes.

Fazenda Campina is an example of how integrated crop-livestock systems increase the supply of nitrogen and other nutrients to the soil, boosting cattle production and benefiting the environment by mitigating the emission of carbon dioxide (CO₂) and other greenhouse gases into the atmosphere.

“Today, the cattle express their DNA far better thanks to the quality of the pasture. Daily weight gain has risen in recent years to 500 grams, up from 100 g under the previous system,” said Juliano Roberto da Silva, an animal care technician employed by the group.

Silva presented the results at an event held on March 26-29, 2019, at Presidente Prudente, São Paulo State, as part of Project NUCLEUS (Nitrogen Use effiCiency via an integrated SoiL-plant systEms approach for the Uk & BraSil). The initiative is funded by FAPESP, the United Kingdom’s Biotechnology and Biological Sciences Research Council (BBSRC) and Newton Fund, Brazil’s National Council of State Research Funding Agencies (CONFAP), the Goiás State Research Foundation (FAPEG) and the Maranhão State Research Foundation (FAPEMA). Researchers and students from the UK, São Paulo, Goiás and Maranhão attended the symposium.

“Crop-livestock integration and crop-livestock-forest integration may not yield a return on all the activities involved, but soil fertility and physics benefit so strongly that the profit earned in just one of these factors offsets any losses incurred in the others,” Juliano Calonego told Agência FAPESP. Calonego is a professor at São Paulo State University’s School of Agronomic Sciences (FCA-UNESP) in Botucatu.

Areas cultivated according to this system are typically used as pasture for two years and as cropland for another two years. In the case of Fazenda Campina, the growth in profitability has not come from the sale of grain crops. According to Silva, sales of 50 bags per hectare are required to cover soybean production costs. Crop yields are almost always insufficient to achieve this goal.

“The loss is more than offset by the gain in soil quality, providing much more nutritious pasture for cattle and hence boosting profitability,” he said.

An experimental farm run by the University of Western São Paulo (UNOESTE), which also participates in NUCLEUS, raises four animals per hectare on a plot dedicated to crop-livestock integration. Pasture occupancy averages less than one animal per hectare in Brazil.

“If you add nitrogen to the soil you double that number,” said Paulo Gomes da Silva, a professor at UNOESTE, during a visit to the experimental farm by participants in the event.

With grain production in Brazil nearing its peak, experts point to degraded pasturelands as the next agricultural frontier. Integrated crop-livestock systems in these areas would enable the nation’s grain production to continue increasing while at the same time promoting pasture restoration.

Knowledge of soils

The main aim of NUCLEUS is to investigate and stimulate efficient uses of nitrogen in agricultural production systems. Researchers have shown that this goal is best achieved by growing forage grasses and grains on the same land, either in rotation or together.

“By keeping the soil covered using grass with deep roots, we prevent nitrogen from leaching into the water table and causing contamination there or being lost to the atmosphere,” said Ciro Rosolem, Full Professor at FCA-UNESP and principal investigator for NUCLEUS Brazil.

Another advantage of crop-livestock integration is that plant cover absorbs CO₂, partly offsetting emissions of methane (CH₄) from cattle by keeping carbon (C) in the system.

The partnership fosters knowledge of the dynamics of different soil types in São Paulo, Goiás, Maranhão and various regions of the UK, as well as knowledge of soil more globally, with scientific results that can be applied not only in the localities studied but also elsewhere.

“It’s very hard to grow crops in compacted soil, which retains less water and resists root penetration. This applies to most of the soils in the world. If we can identify plants that are better adapted to compacted soils, for example, this knowledge can be applied globally,” said Sacha Mooney, a professor at the University of Nottingham and principal investigator for NUCLEUS UK.

The project has contributed to an exchange of experience, given the totally different soil conditions in the UK and Brazil, as well as an exchange of students and researchers. It has also helped identify ways of using new equipment and techniques.

Camila Grassmann, a doctoral student at FCA-UNESP, told participants in the event about her four-month experience at the University of Nottingham, including one of several experiments in which she used soil X-ray tomography, not available in Brazil, as part of her PhD research.

Grassmann studies the interactions between corn and different types of grass to determine which species or varieties make the most efficient use of nitrogen when planted together. Image processing has not yet been completed, but preliminary results suggest that there may not be a significant difference between forage grass species for this particular purpose.

“Using their labs and equipment was very important to make the experiments possible and for my research in general,” she said. “Working with the research team there was also highly rewarding.”

End of a cycle

The project ends this year and has involved more than 40 scientists, 12 institutions, and 12 scientific publications, with more than 20 other scientific publications in progress, as well as exchanges of more than ten graduate students and senior researchers.

“Many interesting findings are emerging in this field in terms of integrated cropping and pasture systems, especially with regard to identification of the best forage grasses,” Mooney said.

He also highlighted the large amount learned by the project team about how soil structure influences root architecture, how this develops in different farming systems, and how it can be improved by the use of plants and liming.

“We’ve also very promisingly shown how to use drones to monitor plant health, and the potential of soil-based sensors to measure soil nitrate. We hope to continue this partnership. Its fruits are starting to appear now,” Mooney said.