Measures could prevent 5.7 million hectares of vegetation in the Amazon and Cerrado from being converted into cropland over the next 15 years
Soybean harvest in Rio Grande do Sul, where crop productivity is high
Silvio Avila / AFP via Getty Images
Soybean production continues to rise in Brazil and has now spread across four biomes: the Pampas, the Atlantic Forest, the Cerrado (a wooded savanna), and the Amazon. In 2019/2020, the total soybean harvest reached 125 million tons, just over twice as much as 13 years prior, according to data from Brazil’s National Food Supply Company (CONAB). Excluding the climate, which humans cannot control, the two factors that most influence productivity levels are total cropland area and crop yield. According to a study published in the scientific journal Nature Sustainability in October by researchers from Brazil, Argentina, and the USA, the impact these two factors had on productivity between 2007 and 2019 was different in the four biomes.
In the Pampas and Atlantic Forest, where soybean has been cultivated for more than half a century and is thus better adapted, increased productivity in the period was due to both significant yield improvement and cropland expansion. In the Cerrado and the Amazon, where soybean cultivation began more recently, the increase was due more to cropland expansion than to greater crop yield (see charts).
If this trend continues in the two biomes over the next 15 years, another 5.7 million hectares of forest and savanna will be converted to soybean cultivation and 1.95 million tons of carbon dioxide (CO2) will be emitted into the atmosphere, according to the study. Of all the greenhouse gases, CO2 contributes most to the planet’s rising average temperature. “The idea is to stop the expansion of cropland area and focus on improving yield, especially in the Cerrado and the Amazon,” says Fábio Marin, an agronomist from the Luiz de Queiroz College of Agriculture at the University of São Paulo (ESALQ-USP) and lead author of the study, which was partially funded by FAPESP. “In these biomes, there is still a lot of room to improve crop yield without having to expand cropland any further.”
In 2019, the total area planted with soybean in the country was almost 37 million hectares, half of it in the Cerrado and 14% in the Amazon. In the Pampas and the Atlantic Forest, which account for 10% and 26% of Brazilian soybean cropland respectively, there is almost no more room for productivity increases, according to the authors of the study. Crop yields are very close to or have already hit the maximum in terms of efficiency gains. In the Amazon and Cerrado, that feat is still a long way off. The researchers estimated this productivity ceiling by planting soybeans in different areas of Brazil where crop conditions are considered ideal or very close to it.
They found a vast difference in productivity between crops that are well cared for and those that are not. Data from Brazil’s Strategic Soy Committee, which holds productivity contests, indicate that the very best producers can achieve 6,000 kilograms (kg) of soybean per hectare. The national average is almost half of that amount, at 3,300 kg per hectare.
According to Rafael Battisti, an agronomist from the Federal University of Goiás (UFG), studies have identified a number of mechanisms in various production stages that contribute to productivity levels. “The sowing date, the choice of cultivar, fertilization, protection against pests and diseases, soil quality, water management, and the use of cover crops in rotation systems are all fundamental to increasing agricultural efficiency,” says Battisti, who is one of the authors of the new article.
In the study, the research group used mathematical models to simulate three routes the soybean production sector could take between now and 2035. The objective was to find a scenario that would allow the industry to grow, but without causing more damage to the environment or increasing greenhouse gas emissions. “All the modeling is based on real climate, soil, and management data, collected from the best possible sources,” says Argentine agronomist Patricio Grassini of the University of Nebraska-Lincoln, USA, another author of the Nature Sustainability article.
The first scenario, dubbed business as usual, was based on no changes to current trends regarding average productivity per hectare and the rate of cropland expansion in the Amazon and Cerrado. Following this path would lead to the production of 212 million tons of soybean in 59 million hectares of cropland in 2035. It would represent success for the economy, but not for the environment. Soybean cultivation would take over 5.7 million hectares currently occupied by forest and savanna, releasing almost 2 million tons of extra carbon dioxide into the atmosphere.
The second scenario describes an alternative path, with productivity improvements within the sector’s historical average but zero cropland expansion nationwide. In these circumstances, crop production would increase until 2029, when all biomes would reach their productivity ceiling, after which the annual yield would remain unchanged at around 140 million tons. The third scenario envisaged the prohibition of soybean cropland expansion in areas not already deforested, but heavy investment in increasing productivity per hectare in the Cerrado and the Amazon, where efficiency is low when compared to the Pampas and Atlantic Forest. Yields would have to double or triple in those biomes, where soybean has been cultivated for less time. In this scenario, production would reach 162 million tons in 2035, but greenhouse gas emissions would be 58% lower than in the business as usual model.
According to the researchers, the results leave no doubt that the third scenario is the ideal solution for a country that needs to reconcile crop production with environmental preservation—with deals between Brazilian agribusiness and countries or blocs like the European Union at risk otherwise. According to Grassini, increasing soybean productivity in the Cerrado and the Amazon without a rise in deforestation could be achieved through a variety of measures.
Yasuyoshi Chiba / AFP via Getty ImagesSoybean farm in Campo Verde, Mato GrossoYasuyoshi Chiba / AFP via Getty Images
The most obvious would be to adopt practices that increase the crop yield, such as planting varieties that are better adapted to each region. Another recommendation is to grow what is known as second-crop or off-season maize in areas where this practice is not yet common. Off-season maize is planted immediately after the end of the soybean harvest, in the same already-fertilized area. It serves as a way of encouraging crop rotation and the production of more food on the same land by using the soil for two different crops at different times of the year. The third option presented by the authors is to increase productivity in the livestock sector by raising more head of cattle per hectare. “That would allow some pasture areas to be freed up for growing soybean and second-crop maize,” says Grassini.
Although the researchers believe the path presented by the study represents a good chance to prosper and gain scale, there are technical challenges to overcome. “One of the obstacles is that there is no single management rule applied to all arable areas on the same farm. Diagnosing the points that limit yield gains and determining strategies in the smallest possible area of land are therefore the best way to reach maximum productivity potential,” explains Battisti. The researchers point out that these measures do not significantly increase costs and can be adopted by soybean producers with farms of any size.
In the case of the Amazon specifically, beyond increasing productivity and curbing environmental destruction, there is another dilemma still to face, says Brazilian public administrator Salo Coslovsky, an associate professor at New York University who specializes in the development of the Amazon. “Monoculture on an industrial scale should be seen from the same perspective as hydroelectric dams and intensive mining in the Amazon. They can all be economically profitable and even important activities for their respective municipalities, states, and the country. But they do not usually generate many direct jobs and they have a high potential to cause social and environmental damage,” says Coslovsky.
Projects 1. Brazilian agricultural efficiency atlas: Assessing the potential for sustainable intensification of Brazilian agriculture (no. 17/20925-0); Grant Mechanism Regular Research Grant; Principal Investigator Fábio Marin (USP); Investment R$183,930.04. 2. Brazilian yield-gap atlas: Assessing the potential for sustainable intensification of Brazilian agriculture (no. 17/50445-0); Grant Mechanism Regular Research Grant; Program Sprint; Agreement University of Nebraska-Lincoln; Principal Investigator Fábio Marin (USP); Investment R$17,001.16.
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