Farming practices in China could be designed to simultaneously improve yields and reduce environmental damages substantially, according to a new study by Stanford biology professor Peter Vitousek and a team of his colleagues at China Agricultural University.

Vitousek is the Clifford G. Morrison Professor in Population and Resource Studies in the Department of Biology and is a faculty affiliate of the Center on Food Security and the Environment at Stanford University. He also is a senior fellow at the Stanford Woods Institute for the Environment and is a professor, by courtesy, in the School of Earth Science’s Department of Environmental Earth System Science.

The research paper, published in Nature, compared current farming practices for staple crops corn, wheat and rice in Eastern and Southern China to three alternative approaches:

• incremental improvements of the current method, aimed at boosting crop growth and improving environmental quality;

• a yield-maximizing approach with no regard to either financial or environmental costs; and

• an "integrated soil-crop system management" (ISSM) approach that used crop models to redesign the production system.

The integrated soil-crop system approach aims to tailor decisions like crop selection, planting, sowing, and nutrient management to each field’s conditions in order both to enhance yields and to minimize environmental damage.

Nitrogen fertilizer is used extensively in modern agriculture – and nowhere more than in China.  Overall, Chinese farmers overuse fertilizer, with much of it ultimately polluting the air and water and contributing to hundreds of thousands of premature deaths each year. The production and transport of fertilizer also contributes significantly to agriculture's share of greenhouse gas emissions that fuel climate change. 

In total, the team tested the four farming methods in 153 site-years of experiments between 2009 and 2012 in widely distributed sites within China’s regions of intensive agriculture. Of the four methods, the yield-maximizing approach produced the highest yields of corn, wheat and rice. Yields from ISSM treatment were a close second, reaching 97-99% of the levels seen in yield-maximizing fields. Crops grown in the ISSM approach also required much less fertilizer, and used it much more efficiently, resulting in nearly no wasted nitrogen and significantly lower greenhouse gas emissions.
 

 “This is exciting work, because the joint challenges of increasing agricultural yields and reducing the environmental costs of agriculture are particularly stark in China – which has less farmland than the United States, a population that’s four times greater, and really horrendous levels of air and water pollution,” Vitousek said.  “If we can combine much higher yields with much lower environmental consequences in China, there is real hope that those challenges can be met around the world.  It’s globally significant that agricultural science in China is meeting these challenges in fundamental ways, and it’s a pleasure to collaborate with our colleagues there.”

The authors predict that if farmers can reach even 80% of the yields seen in the study's ISSM test fields by 2030 (when China’s human population will reach its peak), on the same amount of land that Chinese farmers cultivated in 2012, grain production could then meet demand for both human and animal consumption. This would help ensure food security in China and make China’s role in global food markets to more deliberate and predictable. At the same time, nitrogen losses could be cut by nearly half, thereby saving many lives, and total greenhouse gas emission could fall by one quarter. Moreover, the ISSM approach could be applied in other areas of the world, where it would boost global yields of major grain crops on existing farmland, while simultaneously reducing nitrogen use, greenhouse gas emissions, and economic costs to farmers.

Contact:

Peter Vitousek: vitousek@stanford.edu, (650) 725-1866

Laura Seaman: lseaman@stanford.edu, (650) 723-4920

According to a new study co-authored by Stanford professor David Lobell, the chance of a worldwide slowdown in agricultural yield growth in the next two decades is significantly higher due to global warming.

Lobell and co-author Claudia Tebaldi, a senior researcher at the National Center for Atmospheric Research, set out to estimate the odds of a steep drop in global wheat and corn yield progress under several climate scenarios. The study, “Getting caught with our plants down: the risks of a global crop yield slowdown from climate trends in the next two decades” appeared in Environmental Research Letters.

Lobell said he was motivated to pursue the study based on questions posed by stakeholders and decision makers in governments and the private sector.

“I’m often asked whether climate change will threaten food supply, as if it’s a simple yes or no answer,” Lobell said. “The truth is that over a 10 or 20 year period, it depends largely on how fast the Earth warms, and we can’t predict that very precisely. So the best we can do is try to determine the odds.”

Lobell and Tebaldi calculated the chance of a 10 percent global yield loss from climate change over the next 20 years, which would represent a severe impact on food supply, enough to roughly halve the rate of yield growth.

The short time frame of the study was deliberate, Lobell said. “Many studies have looked at climate and agriculture trends over the coming 50 or 100 years. But the next two decades are when most of the global population growth, and dietary shifts driven by a growing middle class, will occur. The growth rate of food demand will be higher during this time than at any other time in the next century.”

Without human-induced global warming – in other words, in a world with only natural climate variability – the likelihood of a yield drop that large is only 1 in 200. But when the team accounted for global warming, they saw the odds jump to 1 in 10 for corn and 1 in 20 for wheat. “In this study, we did not try to estimate the most likely impacts of climate change on crops,” Lobell said. “Rather, we estimated the likelihood of a really major impact, not because we want to scare people, but because there are many people who want to be prepared for all contingencies.”

“The point of the paper is to move from hand-waving about scenarios of what could go wrong, to specific and transparent estimates of the actual odds,” Lobell said. “The odds are not very high, but they are significant and a lot bigger than they used to be. The people asking these questions are accustomed to planning for scenarios with much less than a 10 percent chance of happening, so it will be interesting to see whether this study has any effect on how they operate.”

Lobell adds that organizations working toward global food security, and related issues such as conflict prevention, are most interested in the next 20 years because their decisions rarely consider the more distant future.  “As scientists, we might prefer to work on time scales in which the answers are clearer, but we also want to be responsive to the actual concerns and questions that decision makers have.”

Lobell is associate professor of Environmental Earth System Science at Stanford and associate director of the Center on Food Security and the Environment. He is also a senior fellow at the Stanford Woods Institute for the Environment and the Freeman Spogli Institute for International Studies.

Contact:

David Lobell: dlobell@stanford.edu

Laura Seaman, Communications and External Relations Manager, Center on Food Security and the Environment: lseaman@stanford.edu

 

Rosamond Naylor, director of the Center on Food Security and the Environment, delivered the keynote address to The University of Vermont's Food Systems Summit in Burlington, VT on June 17-18, 2014. Naylor is the editor of The Evolving Sphere of Food Security (forthcoming, Oxford University Press), the first book of its kind to engage thought leaders from across Stanford’s campus to explore the causes and symptoms of complex topic like global hunger. She will discuss the book's insights on the ways that food security is tied to security of many other kinds: energy, water, health, climate, the environment, and national security. 

The Evolving Sphere of Food Security is available for pre-order from Oxford University Press.

FSE's David Lobell and Chris Field help build scientific consensus on climate change in the newest report from the Intergovernmental Panel on Climate Change. The report emphasizes the deep impacts climate change will have on global crop yields and food security.