Do we need higher yields?
By Sven Ove Hansson, Programme Director
In discussions about the environmental problems in agriculture, the “chase for higher yields” is often the target. Many discussants see the demands for higher yields as the main underlying problem. And to some extent they are right: Some of the technologies that are used to increase yields have considerable negative effects. Pesticides have saved many harvests, but they have also caused considerable damage to nature and in many parts of the world also caused health problems for the growers and their families. In many countries, insecticides are still used that cause considerable harm to non-target insects, including pollinators such as honeybees that are essential both for agriculture and for the wild flora. Environmental problems are also created when yields are increased by irrigating beyond the capacity of local water supplies or fertilization to an extent that leads to eutrophication of surrounding waters.
But that is only one part of the story. The relationship between yields and the environment is in fact quite complex. I will not try to give the whole picture, but let me point out three facts that we need to keep in mind in these discussions.
The first of these facts is that there is no direct or unavoidable connection between increased yields and environmental damage. Some measures that increase yields are negative for the environment, but there are also ways to increase yields that are positive for the environment, or at least only have comparatively small negative effects. Clear examples of this are crop rotation and mechanical and biological pest control, and the use of cultivars with improved tolerance to environmental stresses such as drought, flooding, high salinity, high and low temperatures, and various pests. And of course, we serve the same purpose by reducing the large losses that take place in all parts of the food chain.
The second fact is that the global environmental impact of agriculture depends to a large extent on the total area used for farming. Natural habitats are already so curtailed that a further large-scale expansion of farmland is bound to have devastating effects. If we improve yields on the already cultivated lands in environmentally friendly ways, then this is a double win situation – we reduce the environmental impact on the already cultivated area, and at the same time we save wilderness from cultivation. (Needless to say, our need for farmland is also much influenced by what types of food we choose to eat.)
The third fact I want to emphasize is that plant breeding and modern biotechnology can provide us with environmentally friendly ways to increase yields and thus achieve such a double win situation. One important example is resistance breeding that results in crops capable of resisting pests without the application of pesticides. Resistance breeding can take the form of “back-to-nature” breeding. For instance, a potato variant can be made less susceptible to pests if it is provided with resistance traits that have since long been lost due to breeding that selected for other traits. Thanks to modern biotechnology, plant breeders have efficient tools for resistance breeding.
Another important example is breeding for more efficient use of nitrogen. Plant breeders are currently investigating several traits from wild species that would improve the uptake of nitrogen from soil, or its metabolic use. These can potentially be ways to reduce the use of fertilizers, thereby bringing down eutrophication. Other interesting plant breeding projects aim at improving draught tolerance and photosynthetic efficiency.
In summary, increased yields can be obtained in ways that are bad for the environment, but they can also be obtained in ways that are good for the environment. Plant breeding and modern biotechnology can provide us with new ways to combine improved yields with environmental improvement.