Sun drying is a traditional drying method for reducing the moisture content of paddy by spreading the grains under the sun. The solar radiation heats up the grains as well as the surrounding air and thus increases the rate of water evaporating from the grains.
It is the most common drying method in Asia because of its low cost compared to mechanical drying. It requires little investment and is environmentally friendly since it uses the sun as the heat source and therefore produces no CO2.
However, sun drying tends to be labor-intensive and has limited capacity. Temperature control is also difficult in this method and grains can easily be overheat causing cracked grains which leads to low milling quality. It is also not possible to sun dry at night or during rain.
The following are recommended options for sun drying:
If sun drying is managed properly, it can produce high-quality grain. To improve sun drying:
Additional measures to maintain optimum quality during sun drying
Fact sheet: Sun drying