Two samples of last year’s straw, left, next to two samples of this year’s pink-tinged straw, rightSTUART ALEXANDER / AGRII

Farmers in East Anglia saw something very odd when they harvested straw this year — the straw was pink. This crop was so puzzling that samples were sent away for laboratory analysis, which revealed that the straw had three times its normal level of potash. This is a valuable fertiliser used by arable farmers for supplying potassium, a key nutrient for plant growth. It was these phenomenal levels of potash that had turned the straw pink.

This phenomenon stemmed from the long drought this summer, when East Anglia was one of the hottest and driest regions in the UK, with only 59 per cent of its usual rainfall. The shortage of rain carried on through September.

Normally, as cereal crops mature their stems dry out,…