54 BULLETIN 1067, U. S. DEPARTMENT OF AGRICULTURE. 
Figure 9 indicates the total cost per acre per year, including fuel, 
supplies, labor, and fixed charges, of pumping plants of various types 
in the southern prairie region, where an average of 29 inches of depth 
of water is pumped annually. The cost of the fuel, as assumed, is 
given in Table 36; labor charges are shown in figure 8; the fixed 
charges are assumed as the mean of the fixed charges for the year 1919, 
as shown in figure 8. It will be noted that the cost decreases as the 
size of the project increases. The average cost per acre of operating a 
pumping plant for a project of 3,000 acres is approximately $1 per 
acre per year more than for a project of 7,000 acres. This is 
an incentive toward reclaiming lands by pumping in fairly large units. 
From figure 9 it will also be seen that with the assumptions made 
the most expensive plants for projects with acreage 2,400 or more 
is the steam plant with slide-valve engine. There is little choice 
between the simple Corliss engine and the compound condensing 
type, the former having a slight advantage for projects of more than 
5,000 acres and the latter being a little cheaper for projects between 
2,000 and 5,000 acres. The cheapest plant of all has internal-com- 
bustion engines, and the difference in various plants will depend 
quite largely on the price paid for fuel. 
While the above analysis is for a set of conditions that are assumed 
as typical, different conditions will modify the results, and correc- 
tions in computations may be quickly made to fit special conditions. 
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