Jury-Law books

Irrigation when fully developed may reclaim not to exceed 5 per cent
of this area. From any point of view, therefore, the possibilities
involved in dry-farming in the United States are immense.
Dry-farm area of the world
Dry-farming is a world problem. Aridity is a condition met and to be
overcome upon every continent. McColl estimates that in Australia,
which is somewhat larger than the continental United States of
America, only one third of the whole surface receives above 20
inches of rainfall annually; one third receives from 10 to 20
inches, and one third receives less than lO inches. That is, about
1,267,000,000 acres in Australia are subject to reclamation by
dry-farming methods. This condition is not far from that which
prevails in the United States, and is representative of every
continent of the world. The following table gives the proportions of
the earth's land surface under various degrees of annual
precipitations:--

Annual Precipitation Proportion of Earth's Land Surface
Under 10 inches 25.0 per cent
From 10 to 20 inches 30.0 per cent
From 20 to 40 inches 20.


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