Abstract:
Paddy harvesting is the process of collecting the mature rice crop from the field which consists of activities such as cutting,
handling, threshing and cleaning. Cutting, threshing and cleaning plays an important role to reduce postharvest losses. Lower
performance of traditional harvesting process, labour shortage, reduced turn-around time and use of high yielding varieties have
inevitably forced farmers to shift into mechanical grain harvesting in Sri Lanka. Rice milling is carried out to produce an edible
polished or white rice product from harvested rough rice. Head rice yield is considered for marketing purposes because broken
rice has low price in the market. Field survey was conducted in Polonnaruwa, Ampara and Hambanthota districts to identify most
popular types of combine harvesters operating in the above districts. Paddy samples were collected from harvest of two most
popular models of combine harvester in triplicate. Paddy sample of 1m2 area from every paddy field were harvested separately by
manual harvesting followed by manual threshing and cleaning in laboratory as control sample of relevant paddy field. Moisture
content of the paddy grains were measured in the paddy field using digital moisture meter before harvesting. Paddy samples were
subjected to sun drying until the moisture content come down to 14±1% before the quality analysis in the laboratory. Each paddy
sample was analyzed for moisture content, chaff percentage and head rice yield percentage (HRY). Paddy was milled using
laboratory scale rubber roll sheller and abrasive polisher. Chaff content percentage was measured by adding 100 ml of paddy to
water and volume of chaff was measured using graduated cylinder. HRY was calculated dividing the weight of grain partials,
which are larger than the 3/4 of the grain, by weight of paddy sample. HRY between the two combine harvesting machine models
evaluated were not significantly different at p<0.05 and also it was not significantly dependent on the harvesting methods such as
combine harvesting and manual harvesting. The chaff content was significantly higher in model-2 in comparison to con
