Environmental Policy
Runner-up: What sustainable agriculture can do
“Resource-Conserving Agriculture Increases Yields in Developing Countries” by Jules N. Pretty, Rachel E. Hine, and James I. L. Morison, University of Essex (U.K.); Andrew D. Noble, International Water Management Institute (Thailand); Deborah Bossio, International Water Management Institute (Sri Lanka); John Dixon, CIMMYT (Mexico); and Frits W. T. Penning de Vries, Institute for Atmospheric Sciences, Chinese Academy of Sciences, 2006, 40 (4), 1114–1119.
Everything about this study was big: more than 200 agricultural projects, dozens of countries, decades of combined experience, and the livelihoods of millions of farmers all came into play.
Jules Pretty of the University of Essex (U.K.) led an international and interdisciplinary team to bring together data on successful sustainable agriculture projects from around the world. The result is likely to be the world’s largest review that documents how farmers can grow more food while conserving land and preserving a healthy environment.
The globe-trotting team analyzed 218 projects and then revisited the outcomes of 68 of them 4 years later to examine their efficacy and extent of sustainability. The projects included both privately and publicly funded efforts to improve crop yields while using resource-conserving tactics such as biological pest control; no-till methods to conserve soil carbon and moisture; and agroforestry, which incorporates trees into farmland.
Some of the projects left lasting impressions on Pretty. When he visited Honduras and Guatemala many years ago, he learned of the mucuna bean, also called the velvet bean, which was grown in Mesoamerica as part of maize farming practices for thousands of years. The old ways of growing the legume together with corn brought nitrogen to the soil and raised soil carbon levels?, but these were largely abandoned when European colonists introduced monoculture cropping. Once farmers relearned the ancient polyculture techniques, Pretty saw corn yields jump. Today, he says, about 50,000 farmers in Central America use the method. Pretty found similarly sustainable practices in 57 countries.
How to feed the world’s growing population is, as Pretty puts it, “a contentious issue.” This century saw increases in crop production through the advent and application of chemical fertilizers and pesticides so impressive that they were dubbed “the green revolution”. And abandoning those methods raises fears among many that all of that seeming progress will be undone.
“The thinking had been that for development, you had to sacrifice the environment,” Pretty says. At best, plans tended to emphasize obvious environmental degradation from toxic chemical applications. But sustainable practices in developing countries “could increase production, particularly in the poorest areas, and could also give the extra benefit of producing positive environmental goods, not just ‘not doing harm’,” Pretty says. Those environmental goods include more water, more food, and potentially a more stable climate.
Coauthor John Dixon of the International Maize and Wheat Improvement Center underscores the stakes that drive him to search for sustainable ways to increase cereal production. “The Yellow River stopped flowing in China in the 1990s because of pressure on water resources,” he says. Growing population pressures will only repeat those demands in other parts of the world, he predicts.
For the study, Dixon developed a classification system for farming methods that made comparisons possible. The hardest part, he says, was bridging the gap between formal knowledge—quantifiable data, like crop yields and population size—and so-called “soft” knowledge, such as the ways farmers form groups to manage water resources or the reliability of their access to markets. Though hard to measure, he says, these factors often make the difference between a project’s success and failure.
In the end, the researchers found that with sustainable practices, farmers increased their crop yields by an average of 64%. And this leads Pretty to ask: “Couldn’t we do more of this elsewhere?”
