32 BULLETIX 174, U. S. DEPARTMEXT OF AGRICULTURE. 



tractor, the investment cost per acre is of great importance. Table 

 XIX shows that on the smaller farms of approximately 300 acres the 

 cost per acre for mechanical power is about S7.60, while on the larger 

 farms, averaging about 1,400 acres, the cost per acre is less than 82. 

 Similarly, while the small farms show an investment of about $2 per 

 acre for special equipment, the large farms have only one-fourth this 

 amount. 



In this connection, the value of work horses per acre should also be 

 noted. For the 300-acre farms the cost for work stock is about S3 

 per acre, while for the 1,400-acre farms it is only §2 per acre. 



Especial attention is invited to the difference hi the ratio of the 

 investment cost per acre for the two kinds of power. For mechanical 

 power the investment per acre for the small farms is more than 3^ 

 times as great as for the large farms, while for animal power it is only 

 lh times as great. 



The reason for this difference is probably the fact that a stable 

 of horses, consisting of a number of individual units, can be regu- 

 lated in size to meet actual requirements, the price per unit being 

 practically uniform no matter in what number purchased. On the 

 other hand, the tractor is a complete unit and must be of sufficient 

 power to fulfill the maximum demands which may be made upon it, 

 while the cost per horsepower is greater in the small sizes than in the 

 large ones. In other words, the owner of a 600-acre farm who pur- 

 chases a 30-horsepower tractor will have a lower investment per 

 acre for power than the owner of a 300-acre farm who purchases a 

 15-horsepower tractor, because the lo-horsepower tractor costs more 

 per horsepower than the 30-horsepower outfit; while the owner of a 

 600-acre farm who purchases one work horse for each 30 acres of 

 land, or 20 horses, will have the same investment charge per acre as 

 the owner of a 300-acre farm who purchases one work horse for each 

 30 acres of land, or 10 horses, the cost per horse being nearly the same, 

 no matter in what number purchased. 



From Table XIX it will be seen that the total investment per acre 

 for power on the 300-acre farms is about 810, while for the 1,400-acre 

 farms it is only 84 per acre, although the 300-acre farms have a unit 

 of power for every 12 acres, while the 1,400-acre farms have one unit 

 for every 32 acres. It is evident, therefore, that either the 300-acre 

 farms have more power per acre than is necessary and economical 

 or that the 1,400-acre farms have an inadequate amount of power. 



From a careful study of the data shown, in conjunction with other 

 information available, it is believed that the large farms have a normal 

 acreage per unit of power and that farms of the grain type which have 

 a smaller acreage per horsepower are overequipped and therefore less 

 economically equipped. The owner of a 300-acre farm who has an 

 invested capital of S10 per acre for power and one unit of power for 



