Source: Julia Rosen, NATIONAL GEOGRAPHIC, 10/14/20


ON AN OVERCAST day, Roger Sylvester-Bradley walks along a hawthorn hedge, collecting a thick rind of mud on his leather boots, before stepping into a gently sloping field of barley. He stoops to pluck an ankle-high seedling from the ground and examines its healthy mop of fine white roots. Turning them in his hands, he says, “when you see a plant that’s deficient in phosphorus, it doesn’t look like this.”

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