Between concentration and diffusion: spatial dynamics of soybean production in MATOPIBA through the lens of circular cumulative causation (2000–2024)

In the vast landscape of economic geography, a central question has long puzzled researchers: when a new industry takes root in a region, does it spread out evenly to lift everyone up, or does it cluster in specific spots, leaving others behind? One influential idea, known as circular cumulative causation, suggests that early advantages tend to become self-reinforcing. Imagine a small town that gets a head start in a business; it attracts more workers, better roads, and more investment, which in turn makes it even more successful, while neighboring towns struggle to catch up. This theory challenges the older belief that markets naturally smooth out these differences over time. Instead, it proposes that success breeds more success, creating permanent centers of wealth and activity alongside areas that remain on the periphery. Understanding whether this pattern holds true for modern agriculture is crucial, as it shapes how we view rural development, inequality, and the future of food production in a globalized world.

In the heart of Brazil, a region known as MATOPIBA—stretching across parts of four states and covering hundreds of towns—has become one of the world's most dynamic frontiers for soybean farming. Over the last quarter-century, this area has transformed from a landscape of pastures into a powerhouse of mechanized agriculture. A team of researchers from the University of Brasília set out to trace the journey of soybeans in this region from the year 2000 to 2024. Their goal was not just to count how much soy was grown, but to map exactly where it was grown and to see if the expansion followed a pattern of spreading out to new areas or if it remained tightly concentrated in a few powerful hubs. By analyzing data from every municipality in the region, they sought to determine if the growth of soybeans was creating a more equal distribution of wealth and activity, or if it was deepening the divide between a few rich agricultural centers and the rest of the territory.

The researchers began by looking at the sheer scale of the expansion. In 2000, only 60 towns in MATOPIBA were producing soybeans. By 2024, that number had swelled to 220, indicating that the crop had indeed spread into new territories. However, the story of where the soybeans were grown told a more complex tale. In the early years, production was heavily concentrated; the four largest towns alone produced more than 60 percent of the region's total soy. As time went on, this concentration did decrease, reaching a low point around 2014 when the top four towns accounted for roughly 30 percent of production. This period suggested a genuine diffusion, where the crop was taking hold in many new places. Yet, the story did not end there. After 2014, the trend reversed slightly. The concentration of production began to rise again, with the top towns reclaiming a larger share of the total output. By 2024, the four largest municipalities were once again responsible for nearly 31 percent of the region's soy, and the overall inequality in production remained high.

To understand the shape of this growth, the team used a method that looks at how neighboring towns relate to one another. They found that towns with high soybean yields tended to be located right next to other towns with high yields, forming distinct clusters of success. These "high-high" clusters, representing the most productive core of the region, remained stable and persistent throughout the twenty-four years. At the same time, the researchers identified a growing number of towns that had low yields and were surrounded by other low-yield towns. This pattern suggests that while the crop expanded geographically, the most productive areas did not lose their advantage. Instead, the frontier expanded outward, but the core remained solid, and the less productive areas formed a distinct, consolidated periphery. The data showed that the region did not become a uniform field of equal success; rather, it developed a clear hierarchy with a small group of dominant towns at the top.

The study also examined whether the length of time a town had been growing soy or the size of its farms explained why some towns were more productive than others. Surprisingly, the statistical models did not find a strong, direct link between these factors and the yield levels in the later years. Instead, the most telling difference was the timing of entry. A small group of just 13 towns, which the researchers called the "consolidated core," had been producing soybeans for a long time and accounted for more than 60 percent of the region's total production. In contrast, over half of the towns in the region were classified as an "intermediate frontier," having entered the market more recently and producing significantly less. While the average yield per acre was actually quite similar across these different groups, the total volume of production was vastly different. This indicates that the advantage of the core towns came not from being slightly more efficient, but from having a massive head start and a much larger scale of operation.

The findings support the idea of circular cumulative causation, where initial advantages tend to persist and even grow stronger over time. The expansion of soybeans in MATOPIBA was real and widespread, bringing the crop to hundreds of new towns. Yet, this expansion did not erase the existing inequalities. The early adopters maintained their dominance, and the region evolved into a structure with a powerful, concentrated center and a vast, less productive periphery. The researchers concluded that the growth of this agricultural frontier did not lead to a homogenization of the landscape. Instead, it created a system where the benefits of early entry and large-scale production continued to accumulate in a few specific locations, leaving the rest of the region to follow in their wake without ever fully catching up. This suggests that simply expanding the area of cultivation is not enough to ensure equal development; the history of who started first and how big they grew continues to shape the economic map of the region today.