Effect of paddy drying depth using open-sun drying on drying time and mill recovery of Kaiso variety in eastern Uganda

Abstract

The smallholder rice farmers in the Uganda dry their paddy using open-sun drying method. In most cases the paddy is badly dried and has very high fissure levels. Such paddy on milling contributes to low levels of mill recovery and whole grain in the milled rice. This study was therefore done to find a recommendable paddy-heap depth for open-sun drying of the pre-dominant local Kaiso rice variety in eastern Uganda. In each experiment, the paddy was open-sun dried on cemented floor at ten different depths: control, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm and 110 mm. Drying time showed a linear relationship with paddy drying depth. Mill recovery increased from 57.4 % at control to a maximum average value of 66.3 % and thereafter declined progressively to 63.5 % at 110mm depth. The maximum increment of 14.1 % in whole grain level over control occurred at 70mm depth. Findings from this work indicate that the best drying depths for Kaiso rice variety using open sun drying is 70 – 80mm. However at these depths, the paddy takes 7 – 8 days to dry. It is therefore recommended that more research should be done to reduce the drying time to a manageable level for farmers.