Grasslands, including biomes like the North American prairies and the Eurasian steppes, represent one of Earth’s most widespread terrestrial ecosystems. These areas, defined by their dominant herbaceous vegetation, once covered roughly 40% of the planet’s land surface. The conversion of these vast, open spaces into cultivated fields for row crops represents one of the most extensive land-use changes in human history, fundamentally reshaping global ecology. This transformation is driven by historical settlement patterns, population dynamics, technological innovation, and financial incentives.
Historical Scale of Grassland Conversion
The large-scale conversion of native grasslands to farmlands first gained momentum during the 19th century in the Western Hemisphere. The settlement of the North American Great Plains initiated a massive wave of land transformation that rapidly expanded agriculture westward. Policies like the Homestead Act of 1862 encouraged settlers to cultivate land, often facilitated by the construction of the transcontinental railroad, which provided crucial transportation infrastructure for people and goods.
A similar pattern unfolded across other continents, particularly in the Eurasian Steppe and the Argentine Pampas. These regions, along with the Great Plains, contain some of the most fertile soils on Earth, making them prime targets for agricultural expansion. The most significant global conversion waves occurred in the decades following World War II, fueled by a rising global population and the intensification of farming practices.
Even recently, the conversion rate has remained high in certain areas, particularly in the US Midwest. Between 2008 and 2016, over two million hectares of grassland in 12 Midwestern states were converted to crop production, an area roughly equal to the size of New Jersey. This ongoing transformation has concentrated in areas like the Prairie Pothole Region, where the land is most suitable for high-yield crops like corn and soybeans.
Population Pressure and Changing Dietary Needs
The increase in the global population over the last century has placed pressure on food systems. However, the nature of what people are eating, often referred to as the “nutrition transition,” is a more direct driver of grassland conversion. As incomes rise across the globe, there is a distinct shift toward diets richer in meat, dairy, and processed foods.
This increased demand for animal products requires substantial amounts of feed, primarily cereal grains and protein crops like soy. Globally, livestock production utilizes nearly 80% of all agricultural land, encompassing grazing pasture and land dedicated to growing feed. Consequently, approximately one-third of the world’s total arable land is used to cultivate crops specifically for animal consumption, not for direct human food.
The land needed to produce this feed is a major factor in converting native grasslands. The production of energy-rich feed crops alone requires about 0.55 billion hectares, or 40% of the global arable land. This demand incentivizes the conversion of marginal grazing lands into high-yield, row-crop fields for corn, soy, and wheat. These crops are the foundational ingredients for industrial animal feed, driving the loss of natural pastureland around the world.
Technological Advances and Soil Attributes
The conversion of grasslands was physically enabled by the inherent quality of the soil and major leaps in agricultural technology. Grassland soils, often classified as Mollisols or Chernozems, are among the most fertile on the planet. They are characterized by a thick, dark, organic matter-rich surface horizon that is base-rich and extremely productive for crops.
The challenge for early farmers was not the soil’s fertility, but its physical structure, which was bound together by the dense, fibrous root systems of prairie grasses. This tough, root-bound sod was too difficult for early cast-iron plows to break and often caused them to clog. This problem was solved by the invention of the steel plow by John Deere in 1837.
The polished steel surface of the new plow was self-scouring, meaning the sticky, rich prairie soil would not adhere to it, allowing the blade to efficiently cut and turn the dense sod. This innovation was paired with the later introduction of large-scale mechanization, such as tractors, which amplified the speed and scale of conversion. These technological advancements provided the physical capability to transform millions of hectares of resilient grassland into cultivated farmland.
Economic Drivers and Government Policy
The underlying decision to convert grassland is largely driven by the relative profitability of growing cash crops compared to using the land for grazing livestock. From an economic perspective, land use decisions are highly sensitive to global commodity prices. When prices for crops like corn and soybeans are high, the financial incentive to plow marginal grassland for planting becomes overwhelming, often allowing farmers to recover conversion costs quickly.
Government policies frequently reinforce this financial motivation through agricultural support programs. In the United States, federal programs like crop insurance and commodity subsidies often favor the production of annual row crops over the maintenance of perennial grasslands. The Renewable Fuel Standard, a US policy promoting the use of biofuels, increased demand for corn, which incentivized the conversion of grasslands to meet the rising market price.
These policies, alongside land grants and price supports, create a legislative environment that makes converting natural ecosystems into high-yield monocultures the most economically rational choice for many landowners. The result is a continuous pressure on the remaining grasslands, as their financial return from grazing often cannot compete with the potential profits from subsidized commodity crops.