A new meta-analysis suggests farmers should take a hybrid approach to producing enough food for humans while preserving the environment.
Agriculture has supplanted 70 percent of grasslands, 50 percent of savannas and 45 percent of temperate forests as a result of global climate changes. Modern commercial farming is also the leading cause of deforestation in the tropics and one of the largest sources of greenhouse gas emissions, a major contributor to the ongoing maul of species known as the “sixth extinction,” and a perennial source of nonrenewable groundwater mining and water pollution.
To restrain the environmental impact of agriculture as well as produce more wholesome foods, some farmers have turned to so-called organic techniques. This type of farming is meant to minimize environmental and human health impacts by avoiding the use of synthetic fertilizers, chemical pesticides and hormones or antibiotic treatments for livestock, among other tactics. But the use of industrial technologies, particularly synthetic nitrogen fertilizer, has fed the swelling human population during the last century. Can organic agriculture feed a world of nine billion people?
Environmental scientists at McGill University in Montreal and the University of Minnesota performed an analysis of 66 studies comparing conventional and organic methods across 34 different crop species. They found that, overall, organic yields are considerably lower than conventional yields but, this yield difference varies across different conditions. When farmers apply best management practices, organic systems, for example, perform relatively better.
In particular, organic agriculture delivers just 5 percent less yield in rain-watered legume crops, such as alfalfa or beans, and in perennial crops, such as fruit trees. But when it comes to major cereal crops, such as corn or wheat, and vegetables, such as broccoli, conventional methods delivered more than 25 percent more yield. But that is quantity, not quality.
The key limit to further yield increases via organic methods appears to be nitrogen – large doses of synthetic fertilizer can keep up with high demand from crops during the growing season better than the slow release from compost, manure or nitrogen-fixing cover crops. Of course, the cost of using 171 million metric tons of synthetic nitrogen fertilizer is paid in dead zones at the mouths of many of the world’s rivers. These anoxic zones result from nitrogen-rich runoff promoting algal blooms that then die and, in decomposing, suck all the oxygen out of surrounding waters.
To address the problem of nitrogen limitation and to produce high yields, organic farmers should use best management practices, supply more organic fertilizers or grow legumes or perennial crops.
In fact, more knowledge would be key to any effort to boost organic farming or its yields. Conventional farming requires knowledge of how to manage what farmers know as inputs – synthetic fertilizer, chemical pesticides and the like – as well as fields laid out precisely via global-positioning systems. Organic farmers, on the other hand, must learn to manage an entire ecosystem geared to producing food – controlling pests through biological means, using the waste from animals to fertilize fields and even growing one crop amidst another.
Organic farming is a very knowledge-intensive farming system. An organic farmer “needs to create a fertile soil that provides sufficient nutrients at the right time when the crops need them.
Source: Scientific American
Featured image credit: Chillymanjaro