amount of water required to produce a pound of dry matter is not the
same for all plants, nor is it the same under all conditions for the
same plant. In fact, as will be shown in a later chapter, the water
requirements of any crop depend upon numerous factors, more or less
controllable. The range of the above German results is from 233 to
774 pounds, with an average of about 419 pounds of water for each
pound of dry matter produced.

During the late eighties and early nineties, King conducted
experiments similar to the earlier German experiments, to determine
the water requirements of crops under Wisconsin conditions. A
summary of the results of these extensive and carefully conducted
experiments is as follows:--


Oats 385
Barley 464
Corn 271
Peas 477
Clover 576
Potatoes 385


The figures in the above table, averaging about 446 pounds, indicate
that very nearly the same quantity of water is required for the
production of crops in Wisconsin as in Germany. The Wisconsin
results tend to be somewhat higher than those obtained in Europe,
but the difference is small.

It is a settled principle of science, as will be more fully