Effect of hammer mill and roller mill variables on cheat (Bromus secalinusL.) seed germination

All alternative method for weed control is to devitalize cheat seed after s econdary cleaning using mechanical devices such as a hammer mill and a roll er mill that would be mounted on the combine The effect of hammer mill shaf t speed, screen size, feed rate, and hammer configuration; and roller mill roll gap and roll speed differential on cheat seed germination were investi gated. Germination decreased as hammer mill shaft speed of number of hammer s increased, and screen opening size decreased The hammer mill setting of 3 ,600 rpm with the 3.2-mm (8/64-in.) screen, 24 hammers, and feed rate of 50 g/s (0.11 lb/s) resulted in 3% cheat seed germination compared to 99% for control and hand-harvested cheat samples. Germination decreased with decrea sing roll gap and with increasing roil speed differential ratio. The combin ation of the highest roll speed ratio investigated (1:1.27) and the narrowe st roll gap 0.1 mrm (0.004 in.) reduced the germination 95%.