Definition of "winnowing"

If God doth suffer his own people and dearest children to be exposed to Satan's temptings and winnowings; Why should any man then doubt of his childship, doubt of his own everlasting condition, and say, that he is none of the child of God because he is tempted?

1646, William Bridge, On Temptation (sermon)

At first I tried to handle the seasonal winnowings with a large three-bin compost device.

2007 October 20, Thomas C. Cooper, “How Green Is My Garden?”, in New York Times‎