Wheat yields are levelling off, even in some developing countries

Nadya Anscombe in Environmental Research Web: Wheat yields have levelled off in many countries around the world, even in regions of greater food insecurity such as India and Bangladesh, say researchers in the US.

Marena Lin and Peter Huybers from Harvard University believe that there are many reasons for this trend, including losses from regional warming, a reduction in some countries in the amount of fertilizer used and some wheat yields possibly being near their yield potential.

"Many studies suggest that global wheat yields are levelling off," Lin told environmentalresearchweb. "But modelling wheat yields is a complex issue and many models do not account for intrinsic interannual variations, their autocorrelation and the differences in the models compared."

..."With the major exception of India, the majority of levelling in wheat yields occurs within developed nations, including the United Kingdom, France and Germany," said Lin. "This levelling coincides with policies in these countries, which appear to have disincentivized yield increases relative to other objectives. It is interesting to note that in these cases, the levelling wheat yield is probably due to management decisions, rather than the reaching of a yield limit."

In India and Bangladesh, however, there seem to be different factors at play. In these two countries, which have greater food insecurity and have been using increasing amounts of fertilizers, wheat yields are also levelling off. "This could be due to the effects of climate change, which may be expected to decrease yield potential," said Lin. "Also, wheat yields in India and Bangladesh are near their estimated yield potential."...

Wheat harvest, Raisen district, Madhya Pradesh, India, shot by Yann, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license