What are three factors that hindered food production in Australia?Chapter 15

The answer to this can be found roughly halfway through
Chapter 15, pages 308-9 in my copy of the book.

Diamond
argues that there are three reasons why food production was very difficult in
Australia.  The first of these reasons was the lack of native mammals that could be
domesticated.  Australia lacked these because it had been cut off from the rest of the
world and had only developed marsupials, most of which were killed off when humans came
to Australia.

The second reason is that Australia has
infertile soils and bad climate.  Diamond says that the El Nino weather patterns make
farming in Australia very difficult even now.

Finally,
Diamond argues that there were very few domesticable plants in Australia.  The only one
that modern agriculture has been able to use is the macadamia nut.  Only two of the top
56 wild grass species in the world are from
Australia.

These three factors combined to mean that food
production would be very difficult to accomplish in Australia.  Therefore, Australian
humans remained as hunter-gatherers.