Nine billion people are expected to inhabit the Earth by 2050. But while the world population is growing, the amount of available cropland, fresh water and other key resources is not. The number of undernourished people already exceeds one billion—how do we feed the world without exacerbating environmental problems and simultaneously cope with climate change?
A special collection of articles in the 12 February issue of Science tackles this question from a variety of angles.
Chinese Soils Acidifying Due to Fertilizer
Chinese agriculture has intensified greatly since the early 1980s—making the country the world’s largest cereal producer, for example—in large part because farmers have ramped up their use of chemical fertilizers. A study in Science now shows a serious drawback to the use of nitrogen fertilizer in China: it has caused the soils to become significantly more acidic, which in the long term reduces their ability to support life.
Naturally acid soils occupy about 30% of the world’s ice-free land and are commonly associated with low levels of biodiversity and productivity. High levels of nitrogen fertilization can drive soil acidification, and the rates of nitrogen fertilizer applied in China, particularly for cereal crops and cash crops such as vegetables grown in greenhouse systems, are quite high compared with North America and Europe, according to Jingheng Guo of China Agricultural University in Beijing and colleagues.
The researchers collected all published data on topsoil pH from 2000 to 2008 and compiled two additional datasets, from the 1980s and 2000s, based on six soil groups. Their analysis of all these data shows that acidification has increased substantially from the 1980s to the 2000s in the major Chinese crop production areas. Such large-scale soil acidification is likely to threaten the sustainability of agriculture and affect the biogeochemical cycles of nutrients and also toxic elements in soils.
Pushing Crops to Perform
Agriculture will need to make some radical changes to meet the world’s needs, and eking more food from existing croplands is an important place to start. In a Perspective article, Nina Fedoroff, science and technology adviser to the U.S. Secretary of State and a faculty member at the University of Washington and her colleagues report that we need to get beyond popular biases against agricultural biotechnology, which could help farmers grow crops that can adapt to increasing temperatures, changes in water supply, and new pest threats.
The authors recommend developing regulatory frameworks for growing genetically modified crops, based on scientific evidence, which they say shows that GM crops have an excellent safety record and important environmental and health benefits. They also acknowledge, however, that not all current crops can be pushed to perform as well in the future as they do now. We will also need additional approaches, such as aquaculture, and dryland and saline agriculture.
In a Review, Mark Tester and Peter Langridge of the University of Adelaide in Australia explain how plant breeding has major potential to help improve food security by providing farmers with crops that have greater yields. Transgenic crops will probably become much more widespread in the coming decade, but in the meantime, emerging genetics techniques are opening more immediate possibilities for accelerating plant breeding and increasing the genetic diversity of seeds.
From High-Tech to Low
Tea producers in Tanzania, sugar cane producers in Brazil, and others around the world are beginning to use a variety of techniques known collectively as precision agriculture, to apply the right treatment in the right place at the right time. As Robin Gebbers of Leibniz-Institute for Agricultural Engineering in Potsdam, Germany, and Viacheslav Adamchuk of the University of Nebraska explain in a Perspective article, precision agriculture can be a useful way to manage both the quantity and quality of agricultural produce.
Initially, it was used to adapt fertilizer distribution to varying soil conditions across a field. Since then, it has expanded to include robotic tractors and other machinery, electronic identification of livestock, customized, automated feeding and milking machinery, and software for tracing and managing the movement of produce from the farm to the supermarket.
Not everyone is focused on such high-tech solutions to food security. In another Perspective, Mario Herrero of the International Livestock Research Institute in Nairobi, Kenya, and colleagues stress that small-holder farmers, working less than two hectares of land, produce more than half the world’s food in mixed crop-livestock systems. While the world’s wealthiest nations have recently pledged U.S. $20 billion to improve global food security, this investment will not be successful unless it targets this oft-overlooked portion of the world’s farmers, the authors say. They argue that these small-holder farmers should be the first target for policies to intensify production by carefully managing fertilizer, water and feed, and should also be supported by improved access to markets, new crop varieties and technologies.
The Need for Strong Governments
A green revolution in Africa and the sustainable globalization of the seafood trade are both possible but will require strong governance and leadership to succeed, according to a pair of articles in the special section.
In a Perspective, Gebisa Ejeta of Purdue University in Indiana says that while Africa missed out on the scientific breakthroughs that revolutionized agriculture in Asia, An African Green Revolution can happen with the help of locally developed and locally relevant technologies, strengthened human capacity and institutional infrastructure, and supportive national policy and leadership.
Strong governance is also necessary for developing countries to develop sustainable seafood industries, according to a Policy Forum by Martin Smith of Duke University in North Carolina and his colleagues. They explain that seafood is critically important to global food security because it provides protein, supports livelihoods, and is a source of foreign exchange around the world, including in many developing countries. With many of the ocean’s fisheries overfished, aquaculture has significant promise for growth, although there are real risks that fish-farming could be unsustainable, both financially and environmentally.
In their article, Smith and his colleagues consider a variety of case studies from around the world and find that when developing countries export their seafood at low prices, they get short-term benefits but damage the prospects of long-term sustainability. They conclude that seafood’s role in food security hinges on the ability of governments and other institutions to protect and improve ecosystem health in the face of increasing pressures from international trade and climate change.
How to Count the World’s Hungry
“Global food security”—it’s undoubtedly a critical goal, but what does it actually mean, and how do we measure it? Christopher Barrett of Cornell University in New York explains in a Perspective article that food security is an elusive concept but we need to improve our understanding and measurements in order to direct scarce resources to where they can do the greatest good. Food security is commonly thought to rest on three pillars: availability, access, and utilization. Better data in each of these categories may soon come from a variety of advances, including more organized, improved survey networks.
The 12 February 2010 special issue of Science’s also includes a related package of 11 stories by the journal’s news team, covering everything from pest control to possible changes in human diets.
Listen to Rob Frederick’s Science Podcast interview  with Nina Fedoroff, science and technology adviser to the U.S. Secretary of State.
Listen to Rob Frederick’s Science Podcast interview  with Christopher Barrett from Cornell University.