Drying Grain for Storage: Warm Air That Carries the Water Away

Grain harvested damp heats, moulds and spoils in the bin. Left to dry in the field it shatters and is lost. Drying brings it down to a moisture at which it keeps — the figure storage guidance gives for the crop and the length of storage, commonly around 13–14 % (wet basis) for wheat — by blowing air through it, warmed so that it can carry more water. Everything about a dryer follows from two calculations: how much water must go, and how much it takes each kilogram of air to carry it. The air's temperature and humidity decide both how far the grain can dry and how much fuel it costs. This rung works out the water to remove, the air and heat it needs, and dries a batch of wetted wheat on the bench, weighing it as it goes.