Benin solar market garden project one of five most hopeful energy projects of 2012
The Center on Food Security and the Environment is a joint effort of the Freeman Spogli Institute for International Studies and the Stanford Woods Institute for the Environment.
FSI scholars approach their research on the environment from regulatory, economic and societal angles. The Center on Food Security and the Environment weighs the connection between climate change and agriculture; the impact of biofuel expansion on land and food supply; how to increase crop yields without expanding agricultural lands; and the trends in aquaculture. FSE’s research spans the globe – from the potential of smallholder irrigation to reduce hunger and improve development in sub-Saharan Africa to the devastation of drought on Iowa farms. David Lobell, a senior fellow at FSI and a recipient of a MacArthur “genius” grant, has looked at the impacts of increasing wheat and corn crops in Africa, South Asia, Mexico and the United States; and has studied the effects of extreme heat on the world’s staple crops.
Evaluating the contribution of weather and its individual components to recent yield trends can be useful to predict the response of crop production to future climate change, but different modeling approaches can yield diverging results. We used two common approaches to evaluate the effect of weather trends on maize (Zea mays L.) and wheat (Triticum aestivum L.) production in 12 U.S. counties, and investigate sources of disparities between the two methods. We first used the Decision Support System for Agrotechnology Transfer (DSSAT) model from 1984 to 2008 to evaluate the contribution of weather changes to simulated yield trends in six counties for each crop, each county being located in one of the top 10 U.S. producing states for that crop. A parallel analysis was conducted by multiplying inter-annual weather sensitivity of county-level yields with observed weather trends to estimate weather contributions to empirical yield trends. Weather had a low (maize) to high (wheat) contribution to simulated yield trends, with rain having the largest effect. In contrast, weather and rain had lower contributions to empirical yield trends. Along with evidence from previous studies, this suggests that DSSAT may be too sensitive to water thus inflating the importance of rain. Moreover, the time period used to compute yield trends also had a large effect on the importance of weather and its individual components. Our results highlight the importance of using multiple computation approaches and different time periods when estimating weather-related yield trends.
Currently, more than two-thirds of the population in Africa must leave their home to fetch water for drinking and domestic use. The time burden of water fetching has been suggested to influence the volume of water collected by households as well as time spent on income generating activities and child care. However, little is known about the potential health benefits of reducing water fetching distances. Data from almost 200 000 Demographic and Health Surveys carried out in 26 countries were used to assess the relationship between household walk time to water source and child health outcomes. To estimate the causal effect of decreased water fetching time on health, geographic variation in freshwater availability was employed as an instrumental variable for one-way walk time to water source in a two-stage regression model. Time spent walking to a household’s main water source was found to be a significant determinant of under-five child health. A 15-min decrease in one-way walk time to water source is associated with a 41% average relative reduction in diarrhea prevalence, improved anthropometric indicators of child nutritional status, and a 11% relative reduction in under-five child mortality. These results suggest that reducing the time cost of fetching water should be a priority for water infrastructure investments in Africa.
Scientists are making progress in helping millions of wheat farmers adapt to hotter conditions, but the gains have been uneven, reports a new study led by Stanford University. New approaches to breeding are needed to withstand increasingly common heat waves and keep pace with growing global food demand.
Wheat is the most widely grown crop in the world; unfortunately it is also one of the most sensitive to future global warming. Scientists around the world strive to develop new wheat varieties each year that incorporate improved features, much like car companies release new models each year. Different strategies are commonly used; some target fully irrigated conditions that favor very high yields, while others focus on dry and hot conditions where yield maintenance under stress is a priority.
The team, which includes scientists from Stanford and the International Maize and Wheat Improvement Center (known as CIMMYT), evaluated 25 years of data from historical trials around the globe and analyzed the outcome of different past breeding approaches to help prioritize future strategies. The fully irrigated nursery, known as the elite spring wheat yield trials, produces varieties that are released for the majority of wheat farmers in countries like India and Egypt each year. While cultivars selected under stressed conditions showed significant yield progress at higher temperatures, the elite trials did not.
“There has been very impressive progress in improving yields for the elite varieties at the cooler temperatures that wheat prefers,” explains lead author Sharon Gourdji, a post-doctoral scholar in Stanford’s department of Environmental Earth System Science and Center on Food Security and the Environment (FSE).
“However, to date, our analysis shows a lack of yield gains for these varieties in hot environments over the past 25 years. Along with the gains in cool conditions, this means that the yield difference between cool and hot conditions is getting larger.”
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A CIMMYT researcher plants wheat seed in pots in the center's greenhouse facilities. Photo credit: X. Fonseca/CIMMYT
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"I think we have learned that the current main approach to breeding won't quite cut it in terms of adapting wheat to climate change,” said co-author David Lobell, assistant professor in Environmental Earth System Science and FSE center fellow. “That is useful information as breeding centers try to raise their game to contend with long-term warming."
Lobell notes that there are good reasons why improved heat tolerance for the elite varieties has not happened naturally.
“Breeding is tough since scientists are aiming for so many traits at once – for example, disease resistance, high yields, and good quality for bread making. Adding heat tolerance is like telling a scout looking for a superstar athlete, ‘by the way, make sure he’s a straight A student’,” said Lobell.
One important lesson from the study is that sifting through historical data can help identify what works and what does not.
“It can often be a hard sell to have breeders take the time to send their data back once they have selected their varieties and moved on,” explains CIMMYT wheat physiologist and co-author Matthew Reynolds. “This study clearly demonstrates the advantage of having these data to assess progress. It shows the genetic potential of wheat to adapt to warmer-than-usual conditions, and reinforces the value of screening under stress as a strategy for adaptation to climate change.”
The progress in the nursery targeted towards stress conditions shows that it is possible to make sizable gains in improving heat tolerance. But whether this can be combined with continued high performance under cooler conditions remains to be seen.
“It is critically important for farmers that they not only survive the bad or hot years, but that they can take full advantage of the favorable years” says Gourdji. “What is needed is a breeding strategy that can successfully achieve both.”
This work was supported by a grant from the Rockefeller Foundation. Additional co-authors of the study include CIMMYT’s Ky Mathews and Jose Crossa.
Genetic improvements in heat tolerance of wheat provide a potential adaptation response to long-term warming trends, and may also boost yields in wheat-growing areas already subject to heat stress. Yet there have been few assessments of recent progress in breeding wheat for hot environments. Here, data from 25 years of wheat trials in 76 countries from the International Maize and Wheat Improvement Center (CIMMYT) are used to empirically model the response of wheat to environmental variation and assess the genetic gains over time in different environments and for different breeding strategies. Wheat yields exhibited the most sensitivity to warming during the grain-filling stage, typically the hottest part of the season. Sites with high vapour pressure deficit (VPD) exhibited a less negative response to temperatures during this period, probably associated with increased transpirational cooling. Genetic improvements were assessed by using the empirical model to correct observed yield growth for changes in environmental conditions and management over time. These ‘climate-corrected’ yield trends showed that most of the genetic gains in the high-yield-potential Elite Spring Wheat Yield Trial (ESWYT) were made at cooler temperatures, close to the physiological optimum, with no evidence for genetic gains at the hottest temperatures. In contrast, the Semi-Arid Wheat Yield Trial (SAWYT), a lower-yielding nursery targeted at maintaining yields under stressed conditions, showed the strongest genetic gains at the hottest temperatures. These results imply that targeted breeding efforts help us to ensure progress in building heat tolerance, and that intensified (and possibly new) approaches are needed to improve the yield potential of wheat in hot environments in order to maintain global food security in a warmer climate.
The global demand for seafood is rising rapidly with a growing population consuming larger amounts of fish in their diets. Most of the additional demand for seafood is now met by aquaculture as global catches from wild fisheries have stagnated or decreased since the mid-1980s.
Can the aquaculture sector avoid some of the large resource and environmental problems that have plagued the agricultural and livestock sectors during the past several decades?
Aquaculture is now the fastest-growing animal food production sector and will soon supply more than half of the world's seafood. The industry can play a vital role in ensuring access to affordable seafood and in generating income from the sale of seafood in both developed and developing countries.
Although aquaculture has the potential to feed millions of people, some types of aquaculture production may severely degrade aquatic ecosystems, pose health risks to consumers, reduce incomes and employment in the capture fisheries sector, and diminish food resources for poor populations.
A study by FSE director Rosamond L. Naylor and Stanford Ph.D. student Dane Klinger explores potential solutions to the industry's range of resource and environmental problems. These include novel culture systems; alternative feed strategies; and species choices by stage of adoption, benefits, costs and constraints. The study also considers promising technologies and policies that could provide incentives for innovation and environmental improvement.
"Rethinking aquaculture production with an integrated mind-set is needed to tackle the simultaneous challenges of feed and energy demands, containment of wastes, pathogens, and escaped fish, land and water requirements, and consumer preferences," said Klinger.
Environmental regulations, international standards, labeling, and information strategies can help provide incentives to producers to adopt improved technologies and management practices, but they need to be coordinated and promoted with care to prevent excessive costs to producers and confusion for consumers.
Soybean production has become a significant force for economic development in Brazil, but has come at the cost of expansion into non-protected forests in the Amazon and native savanna in the Cerrado. Over the past fifty years, production has increased from 26 million to 260 million tons. Area planted to soybeans has increased from roughly 1 million hectares in 1970 to more than 23 million hectares in 2010, second only to the United States.
A new study out of Stanford University examines the role of institutions and supply chain conditions in Brazil’s booming soybean industry and the relationship between soy yields and planted area. With the demand for soybeans projected to increase far into the future a better understanding of the economic and institutional factors influencing production can help policymakers better manage land use change.
Using county level data the researchers found that soy area and yields are higher in areas with high cooperative membership and credit levels, and where cheap credit sources are more accessible. Cooperatives help producers secure lower prices for inputs or higher prices for outputs through group purchases and sales. They also enable producers to store their grain past the harvesting period and sell it when prices are higher.
“This suggests that soybean production and profitability will increase as supply chain infrastructure improves in the Cerrado and Amazon,” said lead author Rachael Garrett, a PhD student in Stanford’s Emmett Interdisciplinary Program in Environment and Resources.
The authors did not find a significant relationship between land tenure and planted area or land tenure and yields. But found that yields decline and planted area actually increases as transportation costs increase. More importantly, the study showed counties with higher yields have a higher proportion of land planted in soy.
“Policies intending to spare land through technological yield improvements could actually lead to land expansion in the absence of strong land use regulations if demand and per hectare profits are high,” said co-author Rosamond L. Naylor, director of Stanford’s Center on Food Security and the Environment.
The current Forest Code requires rural land users in the Amazon to conserve 80% of their property in a ‘Legal Reserve’, and landowners in the Cerrado to conserve 20%. Historically, illegal clearings have been common and enforcement of the Legal Reserve requirements remains poor.
While this study focuses on Brazil, the results underscore the importance of understanding how supply chains influence land use associated with cash crops in other countries. Future demand for soybeans, as well as for cash crops like Indonesian palm oil, will continue to grow as demand for cooking oil, livestock feed, and biodiesel increase with income growth and changing dietary preferences in emerging economies.