Ecology: Crop diversity increases crop stability

Greater crop diversity strongly increases the stability of the national annual yield, according to a paper published online this week in Nature.

Increasing global food demand, low grain reserves and climate change threaten the stability of food systems on national and global scales. During the past decade, drought and extreme heat caused grain yields to decline in some of the world’s major agricultural regions, including Australia, Russia and the United States. Policies to increase yields, irrigation and the tolerance of crops to drought have been proposed as stability-enhancing solutions.

One potential solution is the crop diversity-stability hypothesis, proposed by Delphine Renard and David Tilman. The authors examined the relationship between crop diversity and the stability of national yield using five decades of data on the annual yields of 176 crop species in 91 nations. They found that the temporal stability of national yield directly benefits from increased crop diversity. Small increases in stability, in turn, lead to greatly decreased probabilities of years with major national yield declines. The findings suggest that increasing the crop diversity of a nation could potentially counteract the effect of increased climatic variability.