The one from Mao about people becoming fertilizer is true but taken wildly out of context. He was basically talking about the circle of life (emphasis mine):

Partial splits are normal. Since last year, splits occurred within the leadership group in half of the provinces in the nation. Take the human body for instance. Everyday hair and skin are coming off. It is the death of a part of the cells. From infancy on, a part of the cells will die. It benefits growth. Without such destruction, man cannot exist. It would have been impossible if men did not die since the time of Confucius. Death has benefits; fertilizer is created. You say you don’t want to become fertilizer, but actually you will. You must be mentally prepared. Partial splits occur everyday. There will always be splits and destruction. The absence of splits is detrimental to development. Destruction in entirety is also a historical inevitability. As a whole, the party and the state, serving as the tools of the class struggle, will also perish. But before the completion of its historical mission, we must consolidate it. We do not hope for splits, but we must be prepared. Without preparation, there will be splits. With preparation, we will avoid big splits. Large and medium splits are temporary.

https://www.marxists.org/reference/archive/mao/selected-works/volume-8/mswv8_23.htm

Edit: I fixed a typo where an exclamation mark was added incorrectly

I have seen the bold part, or sometimes even the first half, taken completely out of context to be about the famine that only started the following year.

As an aside, Mao’s cadence is so funny, though it might be in translation. Just look at that second sentence, “You say you don’t want to become fertilizer, but actually you will.”