**2.1 Primary causes**

Agricultural commodities like food grains are when grown and transported to consumers are subjected to various agricultural operations like harvesting, threshing, milling, packing, storage etc. The large number of losses may occur when harvesting is not done at adequate moisture content and time of harvesting. Delayed harvesting or too early harvesting may subject the crop severe losses by various factors like attack of birds, rodents, microbes, natural calamities etc [4, 5]. Threshing and cleaning are usually done to separate grains from panicles. However, threshing losses can occur in case of seed splitting, incomplete separation of seed from source, seed cracking due to excessive force [4, 6] . Delayed threshing result in loss of quality and quantity of commodities. In order to prolong the storage of food grains, it is necessary to store the commodities at safer moisture content. Improper drying result in microbe growth in grains and is not desirable for storage and grinding operations. Thus, drying is an important postharvest technology in order to improve quality, prevention from insects and rodents and for transportation [7, 8]. Lack of proper transportation facilities may result in loss of commodities to greater extent. However, the problem of loss due to transportation are relatively less in developed countries due to proper roads, infrastructures and processing equipment.
