Analysis of straw bruising and sieving system on performance of modified wheat straw combine for better straw quality

Wheat straw is a major feed source for ruminants. To retrieve the wheat straw and stubbles left after wheat harvesting operation with grain combines, another machine i.e. straw combine is used. But it was observed that the quality straw collected by straw combines contains dirt particles which increases total ash content of straw and that are harmful for animal health. To reduce energy requirement and to reduce total ash content, straw combine was developed with sieving system. Modified straw combine consisted of a 1.53×0.82 m screen with 0.208 mm opening sieving system, which was fixed below the bruising cylinder. Field evaluation of the modified straw combine carried out at two level of concave bar spacing (10 & 14 mm), three feed rate (14, 16.5 & 19 q/h) and three cylinder speed (28.45, 32.25 &36.04 m/s). It was observed that at 14 mm concave bar spacing, 28.45 m/s cylinder speed, minimum net specific energy requirement was found to be 0.42 kWh/q when the feed rate was 19 q/h. During straw bruising, average straw length varied from 12.22-20.23 mm and 16.07-25.26 mm at concave bar spacing of 10 mm and 14 mm, respectively. The maximum split straw percentage was recorded to be 98.43% at the cylinder speed of 36.04 m/s and feed rate of 19 q/h at concave bar spacing of 10 mm. The total ash content in the straw was found to be 9.61 %, at the concave bar spacing of 14 mm and 14 q/h feed rate