Economic Growth, Described Through a Soil Tillage Parable


During my summers in college, I interned for the Natural Resources Conservation Service (NRCS), the environmental protection arm of the US Department of Agriculture. Drawing the shortest straw, my placement was in the remote town of Ritzville Washington, over an hour from Spokane or any tree. A hamlet of 2,000 people surrounded by miles of dryland wheat farmers and little else. Rainfall averaged 11 inches a year. With groundwater irrigation impossible, the only crop in the region capable of large scale cultivation was soft white winter wheat.

Prior to 1994, the NRCS was named the Soil Conservation Service, reflecting the agency’s primary mission following its establishment in the 1930s to stop the Dust Bowl ravaging the dryland agriculture of the Great Plains. While the agency’s aims have grown over the decades to protect water quality, improve forest health, and even subsidize high tunnel greenhouses for growers, its primary goal continues to be the reduction of soil erosion, particularly in places like Ritzville.

Due to the harsh winters and lack of rainfall in the region, winter wheat in Ritzville was a biennial crop, planted in the fall, sprouting in the spring, harvested in the summer. Following the harvest, the land would fallow for a year for the soil to regain moisture and be tilled before planting would resume the following fall. That traditional agriculture involved heavy tillage, with the fallowed fields tilled well before replanting.

Every summer, winds would pick topsoil off the fallowed fields and blow it away, creating dust storms and soil loss. Unlike the unfortunate Oklahoma farmers during the Dust Bowl, Ritzville was blessed with considerably deeper soils that ran less risk of eroding away to the point of infertility. Nevertheless, the status quo of rampant erosion poised a threat to the community’s agricultural economy, and the dust storms lowered quality of life and lung health.

Eighty years after the agency’s founding, the NRCS’s two primary prescriptions for erosion reduction on dryland farmed areas remain unchanged: Pay farmers to let land lie fallow for a decade or more to recover from continuous use in the Conservation Reserve Program, or pay farmers to reduce their tillage intensity and depth, leaving crop residue on the ground in what’s called “conservation tillage,” through the Environmental Quality Incentives Program.

To understand how tillage affects soil, it’s important to know what “soil” is.

Soil is a three dimensional bioreactor of microorganisms shaped by six major environmental factors: Climate, organisms, slope, parent material, and time. From the biggest visible holes in soil to the smallest pores only visible through a microscope, soil teems with life of all sizes, with trillions of interactions and reactions influencing and shaping the the soil’s chemical and physical properties.

Porosity, or the percentage of soil taken up by pore space, is the single greatest indicator of soil health, affecting nearly every soil property.

More pore space means more space for water that moderates soil temperatures and hydrates nitrogen fixing organisms. It means greater water retention and water availability to plants, as porous soil has smaller holes that are difficult for water to escape from once entered, allowing for a slower release that can sustain plants through drought, raising yields.

Soils with more porosity are naturally more fertile, as the greater space for nitrogen fixing microorganisms increases their diversity and overall numbers in soil. Those microbes and microarthropods contribute to thousands of chemical reactions that increase the bioavailability of nitrogen in soil. That increased space means more interior soil surface area for nutrient ions to bind to, increasing nutrient retention, raising yields.

Similarly to water, fertilizers applied to more porous soils are less likely to rapidly percolate through or run off into surrounding streams, thus becoming more likely to be uptaken by plants, reducing the need for repeat fertilizer application, saving farmers money and reducing the amount of nutrient runoff pollution that ends in rivers and streams. The reduced runoff reduces the velocity of water on and inside the soil, cutting water erosion. Wind erosion declines too, as reduced tillage allows more roots to remain in topsoil, reducing the ability of wind to pick up soil and create dust.

Such complex aggregates are not easy to build, as the complex pore spaces are created over many years by microorganisms, nematodes, worms, and countless other creatures over time as they slowly build their own habitat through the movement of their own bodies.

On first glance, tillage appears to “air out” the soil and increase pore space by tearing up the aggregate and creating larger piles in its wake, much like how when you dig a hole, the dirt in the pile behind you is always bigger than the hole dug. However, the destruction of the soil aggregate causes soil to eventually collapse in on itself, reducing pore space and destroying the microbiomes that exist within the pore spaces, crushing fertility and water/nutrient retention capacity. After a solid rain, that dirt pile collapses in on itself and becomes significantly smaller than when you first dug it.

Farmers don’t choose to till out of any desire to harm the environment or reduce their yields. A farmer can live on their land for 50 years, able to walk their land in pitch blackness without tripping, but have no understanding of the massive microscopic world that lives beneath them, as they are limited by the perspective and tools they have.

Tillage exists for a reason. Traditionally, it has been an outstanding way of eliminating weeds without the use of herbicide, and has become a cultural practice in itself. If your parents and grandparents had farmed the family land using the same technique, why would you change it, especially if it required the purchase of new, expensive equipment on your farm that operates on razor-thin margins? Furthermore, the yield improvements from conservation tillage take time to appear. Farmers switching to conservation tillage must pay for increased herbicide use without seeing yield improvements for years (although farmers do immediately use less fuel when adopting conservation tillage, as the reduced tillage depth reduces energy expenditures from dragging farm implements).

The NRCS steps in to reduce the risk of new technology adoption among heavily risk averse farmers, even if the short term risk yields long term dividends. Ever since the agency’s creation, there has been significant debate over whether said subsidy to already land-rich farmers is truly necessary.

But let’s look at the practice change in a macroeconomic sense.

Fundamentally, economic growth is when there’s an increase goods and services in the economy.

Zero-sum factions of both anti-environmentalists and environmentalists have argued that economic growth is incompatible with environmental protection, as growth depends on increasing the outputs of the economy. The argument typically goes that outputs can only rise when inputs into the economy rise, with inputs being increased extraction of Earth’s raw materials, or the degradation of the public commons like clean air and water. So the argument goes, to protect the environment, humans must engage in “degrowth,” and either become materially poorer, or the human population must decline. Inversely, increased human wealth can only occur at the expense of the environment.

That zero sum thinking ignores the third component to economic growth: Technology, or the ability to create more economic outputs with a fewer number of inputs. Technological improvement isn’t always a new gadget or tool, like a drone making aerial photography cheaper. It’s any innovation that increases process efficiency of input conversion to output. It can be as simple as modifying a practice or technique.

In the case of the Ritzville NRCS, that tool was tillage reduction. A change in cultural practice that reduced fuel and fertilizer use while raising agricultural yields. Using the same amount of land, farmers were able to increase their agricultural yields, thus feeding more of the world, while simultaneously reducing their fuel usage, reducing water pollution runoff, and improving soil health through the creation of greater soil aggregates, all by merely shifting a single practice: intensity of agricultural tillage.

Environmentalists wanting to create a more sustainable future could stand to learn from this parable. “Free lunches” wherein everybody benefits with few to no downsides do exist in economics. Economic growth and environmental protection can occur simultaneously, and even in tandem, as efficiency improvements benefit both objectives. Furthermore, to obtain broad political support, environmental protection needs a buy-in from broad swaths of the electorate. Everyone needs to see themselves benefitting in an environmentally friendly future, even farmers.