In Thailand -where most of the paddy and corn produced is exported- drying is an essential agricultural activity. There is 18-25 per cent moisture in the crops at the time of harvesting, which has to be reduced to 14 per cent to prevent spoilage. During rainy or cloudy days, slow drying in a storage using ambient air offers a better alternative to mechanical dryers. Its advantages include low cost, longer storage period and prevention of yellowing and breaking of grains. In the case of corn, slow drying reduces the unwanted sour smell which is otherwise produced due to high temperature in grain bulk (AIRD News, VoI 14, No 8).