Thorough Tillage System eor Plains oe Colorado. 25 
Wheat . . . 
Barley . . . 
Oats . 
Corn . 
Clover . . . 
Field Peas 
Potatoes . 
453 lbs. water. 
464.1 ” 
503.9 ” 
270.9 ” 
576.6 ” 
477.2 ” 
385.1 ” 
The Utah Experiment Station has found that under semi-arid 
conditions the evaporation is such that wheat requires 750 pounds 
to mature one pound of dry matter. 
Counting the weight of straw necessary to grow 1 bushel of 
wheat (60 lbs.) as 90 lbs. (1 1-2 times the weight of grain), we 
find that it requires 56 1-4 tons of water to produce one bushel of 
wheat in our climate. The moisture required to mature a crop of 
wheat is believed to indicate the maximum amount required by 
most any farm crop in the semi-arid lands of Colorado. 
VII. ANNUAL RAINFALL FOR COLORADO. 
The U. S. Weather Bureau has divided the state into weather 
districts for convenience in making and recording reports. The 
average annual and crop season rainfall in these several districts is 
indicated on the chart given below. These averages are-made from 
the government reports and cover the period observations have been 
made. The minimum is six and the maximum thirty-seven years. 
Through the courtesy of Mr. F. H. Brandenburg, District Fore¬ 
caster for the Rocky Mountain District, we are enabled to give this 
valuable data on the rainfall by districts. 
figure 7 . 
a. Average annual moisture precipitation. 
b. Average precipitation February to August. 
Weather districts are marked by full lines and county limits by dotted 
lines on the chart. 
