Sentence:  If threshed by the flail, the awns and sharp points [of oats] will be less broken and <WSD>hummelled</WSD> than if threshed by machinery. Whatever <WSD>hummels</WSD> the grain most will produce the heaviest bushel, while, of course, extremely little variation will have taken place in the dynamical relation of the kernel and hull. 
Meaning of the word marked with <WSD> tags:  To separate (barley, oats, etc.) from the awns.