Agriculture degrades over 24 million acres of fertile soil every year, raising concerns about meeting the rising global demand for food. But a simple farming practice born from the 1930’s Dust Bowl could provide a solution, according to new Stanford research. The study, published Dec. 6 in Environmental Research Letters, shows that Midwest farmers who reduced how much they overturned the soil — known as tilling — increased corn and soybean yields while also nurturing healthier soils and lowering production costs.
“Reduced tillage is a win-win for agriculture across the Corn Belt,” said study lead author Jillian Deines, a postdoctoral scholar at Stanford’s Center on Food Security and the Environment. “Worries that it can hurt crop yields have prevented some farmers from switching practices, but we found it typically leads to increased yields.”
The U.S. — the largest producer of corn and soybeans worldwide — grows a majority of these two crops in the Midwest. Farmers plucked about 367 million metric tons of corn and 108 million metric tons of soybeans from American soil this past growing season, providing key food, oil, feedstock, ethanol and export value.
Monitoring farming from space
Farmers generally till the soil prior to planting corn or soybeans — a practice known to control weeds, mix nutrients, break up compacted dirt and ultimately increase food production over the short term. However, over time this method degrades soil. A 2015 report from the Food and Agriculture Organization of the United Nations found that in the past 40 years the world has lost a third of food-producing land to diminished soil. The demise of once fertile land poses a serious challenge for food production, especially with mounting pressures on agriculture to feed a growing global population.
In contrast, reduced tillage — also known as conservation tillage — promotes healthier soil management, reduces erosion and runoff and improves water retention and drainage. It involves leaving the previous year’s crop residue (such as corn stalks) on the ground when planting the next crop, with little or no mechanical tillage. The practice is used globally on over 370 million acres, mostly in South America, Oceania and North America. However, many farmers fear the method could reduce yields and profits. Past studies of yield effects have been limited to local experiments, often at research stations, that don’t fully reflect production-scale practices.
The Stanford team turned to machine learning and satellite datasets to address this knowledge gap. First, they identified areas of reduced and conventional tilling from previously published data outlining annual U.S. practices for 2005 to 2016. Using satellite-based crop yield models — which take into account variables such as climate and crop life-cycles — they also reviewed corn and soybean yields during this time. To quantify the impact of reduced tillage on crop yields, the researchers trained a computer model to compare changes in yields based on tillage practice. They also recorded elements such as soil type and weather to help determine which conditions had a larger influence on harvests.
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