Not every effort there is a harvest,
这半句为Not引导的倒装句,there是修饰every effort的副词,译为指代该特定所有做出的努力,后which引导的从句也是修饰前面两句话的.
Every effort there为主语,理解时可调整语序为It is not a fair irreversible propositions that every effort there(主语) is(系动词) not a harvest（宾语）,but each time the harvest must be hard.