The fields outside Mohall, North Dakota, were until recently a collage of blue flax, yellow sunflowers and amber wheat. But today many are uniform patches of green at the peak of the summer growing season.

This new landscape is thanks to farmers such as Eric Moberg, whose 72-row air seeder planted thousands of acres with soyabeans this spring. “We didn’t grow any beans four years ago. Now it’s almost a third of our acre base,” he says.

His windswept county on the Canada border is at the frontier of a shift in world food supply. As emerging Asia eats more chicken and pork, the soyabeans that put muscle on birds and swine have spread across global farms at a faster rate than any other field crop, covering an area 28 per cent bigger than a decade ago.