By monitoring crops through machine learning and satellite data, Stanford scientists have found farms that till the soil less can increase yields of corn and soybeans and improve the health of the soil – a win-win for meeting growing food needs worldwide.

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 comput

Average impacts on corn yields from conservation tillage across the U.S. Corn Belt from 2008 to 2017. Red colors indicate increased yields under conservation tillage, blue colors indicate yield declines.

Improved yields

The researchers calculated corn yields improved an average of 3.3 percent and soybeans by 0.74 percent across fields managed with long-term conservation tillage practices in the nine states sampled. Yields from the additional tonnage rank in the top 15 worldwide for both crops. For corn, this totals approximately 11 million additional metric tons matching the 2018 country output of South Africa, Indonesia, Russia or Nigeria. For soybeans, the added 800,000 metric tons ranks in between Indonesia and South Africa’s country totals.

Some areas experienced up to an 8.1 percent increase for corn and 5.8 percent for soybeans. In other fields, negative yields of 1.3 percent for corn and 4.7 for soybeans occurred. Water within the soil and seasonal temperatures were the most influential factors in yield differences, especially in drier, warmer regions. Wet conditions were also found favorable to crops except during the early season where water-logged soils benefit from conventional tillage that in turn dries and aerates.

“Figuring out when and where reduced tillage works best could help maximize the benefits of the technology and guide farmers into the future,” said study senior author David Lobell, a professor of Earth system science in the School of Earth, Energy & Environmental Sciences and the Gloria and Richard Kushel Director of the Center on Food Security and the Environment.

It takes time to see the benefits from reduced tillage, as it works best under continuous implementation. According to the researchers’ calculations, corn farmers won’t see the full benefits for the first 11 years, and soybeans take twice as long for full yields to materialize. However, the approach also results in lower costs due to reduced need for labor, fuel and farming equipment while also sustaining fertile lands for continuous food production. The study does show a small positive gain even during the first year of implementation, with higher gains accruing over time as soil health improves. According to a 2017 Agricultural Censuses report, farmers appear to be getting on board with the long-term investment and close to 35 percent of cropland in the U.S. is now managed with reduced tillage.

“One of the big challenges in agriculture is achieving the best crop yields today without comprising future production. This research demonstrates that reduced tillage can be a solution for long-term crop productivity,” Deines said.

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David Lobell is also the William Wrigley Senior Fellow at the Stanford Woods Institute for the Environment, a senior fellow at the Freeman Spogli Institute for International Studies and the Stanford Institute for Economic Policy and Research. Graduate student Sherrie Wang is also a co-author. Research was funded by NASA Harvest.

Not many people go into farming to get rich. Low commodity prices, high operational costs and limited profit opportunities cloud the outlook. William Wrigley Professor and FSE Founding Director ROSAMOND NAYLOR gave a keynote presentation on the path toward a more profitable future at an agricultural symposium hosted by the Federal Reserve Bank of Kansas City. See slides from Naylor’s presentation here.

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Widespread cultivation of oil palm trees has been both an economic boon and an environmental disaster for tropical developing-world countries. New research points to a more sustainable path forward through engagement with small-scale producers.

Nearly ubiquitous in products ranging from cookies to cosmetics, palm oil represents a bedeviling double-edged sword. Widespread cultivation of oil palm trees has been both an economic boon and an environmental disaster for tropical developing-world countries, contributing to large-scale habitat loss, among other impacts. New Stanford-led research points the way to a middle ground of sustainable development through engagement with an often overlooked segment of the supply chain (read related overview and research brief).

"The oil palm sector is working to achieve zero-deforestation supply chains in response to consumer-driven and regulatory pressures, but they won’t be successful until we find effective ways to include small-scale producers in sustainability strategies,” said Elsa Ordway, lead author of a Jan. 10 Nature Communications paper that examines the role of proliferating informal oil palm mills in African deforestation. Ordway, a postdoctoral fellow at The Harvard University Center for the Environment, did the research while a graduate student in Stanford’s School of Earth, Energy & Environmental Sciences.

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An oil palm plantation in Cameroon (Image credit: Elsa Ordway)

Using remote sensing tools, Ordway and her colleagues mapped deforestation due to oil palm expansion in Southwest Cameroon, a top producing region in Africa’s third largest palm oil producing country (read about related Stanford research). Contrary to a widely publicized narrative of deforestation driven by industrial-scale expansion, the researchers found most oil palm expansion and associated deforestation occurred outside large, company-owned concessions, and that expansion and forest clearing by small-scale, non-industrial producers was more likely near low-yielding informal mills, scattered throughout the region. This is strong evidence that oil palm production gains in Cameroon are coming from extensification instead of intensification.

Possible solutions for reversing the extensification trend include improving crop and processing yields by using more high-yielding seed types, replanting old plantations, and upgrading and mechanizing milling technologies, among other approaches. To prevent intensification efforts from inciting further deforestation, they will need to be accompanied by complementary natural resource policies that include sustainability incentives for smallholders.

In Indonesia, where a large percentage of the world’s oil palm-related forest clearing has occurred, a similar focus on independent, smallholder producers could yield major benefits for both poverty alleviation and environmental conservation, according to a Jan. 4 Ambio study led by Rosamond Naylor, the William Wrigley Professor in the School of Earth, Energy & Environmental Sciences and a senior fellow at the Stanford Woods Institute for the Environment and the Freeman Spogli Institute for International Studies(Naylor coauthored the Cameroon study led by Ordway).

Using field surveys and government data, Naylor and her colleagues analyzed the role of small producers in economic development and environmental damage through land clearing. Their research focused on how changes in legal instruments and government policies during the past two decades, including the abandonment of revenue-sharing agreements between district and central governments and conflicting land title authority among local, regional and central authorities, have fueled rapid oil palm growth and forest clearing in Indonesia.

They found that Indonesia’s shift toward decentralized governance since the end of the Suharto dictatorship in 1998 has simultaneously encouraged economic development through the expansion of smallholder oil palm producers (by far the fastest growing subsector of the industry since decentralization began), reduced rural poverty, and driven ecologically destructive practices such as oil palm encroachment into more than 80 percent of the country’s Tesso Nilo National Park.

A worker in East Kalimantan, Indonesia, loads palm fruit for transport to a factory that will process it into palm oil (Image credit: Joann de Zegher)

The recently launched Stanford Alumni in Food & Ag group aims to bring together Stanford graduates with a background or interest in food and agriculture issues. Tannis Thorlakson, one of the group’s creators, works as the environmental lead for Driscoll’s in the U.S. and Canada, and recently earned her Ph.D. from Stanford’s E-IPER program. She hopes the group will help alumni stay connected with cutting-edge research and stay up-to-date on news within the food and agriculture space. Thorlakson sat down with FSE to chat about the group and upcoming launch event taking place at the O'Donohue Family Stanford Educational Farm later this month.

Q: What inspired you to create the group and who else was involved?
Thorlakson: It has been exciting to see the increasing enthusiasm for agriculture and food around Stanford's campus during my time there. Between the newly expanded Stanford Farm and the buzz around ag tech, more and more students are interested in careers in food and agriculture. My cofounders Manuel Waenke, Anthony Atlas and I wanted to harness some of this enthusiasm to bring alumni together.

Q: Who is eligible to join?
Thorlakson: At this point, we are focused only on Stanford alumni, but will build collaborations with student groups over time. 

Q: What are your goals or focus areas?
Thorlakson: We have two primary goals; to connect alumni to share insights and opportunities in the food and agriculture space; and to keep alumni connected to campus through events and sharing of cutting-edge Stanford research. 

Q: You have your first event on Oct. 26. What are you hoping to accomplish, who can come, and how can people learn more?
Thorlakson: All alumni and faculty are invited to join. This will be a chance to connect with fellow alumni and learn a bit more about the club. More information here: https://www.stanfordfoodag.com/events.

Q: Anything else you’d like to let others know about?
Thorlakson: We're just getting started, so if you have ideas on how to make this group more relevant to you, please reach out to us at mwaenke@stanford.edu.