30 BULLETIN 174, TJ. S. DEPARTMENT OF AGBICULTUEE. 



These facts, together with others shown in the tables, seem to 

 indicate that the 15-horsepower tractor is giving better average 

 results than any other size. It will he seen that the 15-horsepower 

 tractors also give more favorable operating figures than any other 

 size of tractor. 



While the figures for the different sizes of tractors in Table XVIII 

 show other variations, it is believed most of them are due to causes 

 other than the size of tractor. For example, the number of horses 

 kept, the percentage of night work done, and the percentage of custom 

 work done, increase with the size of the tractor, but this increase is 

 probably due largely to the fact that the larger tractors are usually 

 found on the large farms, as will be noticed by the average sizes of the 

 farms shown in the table. 



SIZE OF FARM. 



In North Dakota, tractors are seldom found on farms of less than 

 320 acres, the average size of the farm on which tractors are used in 

 that State being between 700 and 800 acres. In other States, par- 

 ticularly in Iowa, tractors are frequently found on farms as small as 

 160 acres. As will be seen from Table XIX, however, a very large 

 percentage of tractor owners do custom work with the tractor, indi- 

 cating that the home farm does not furnish sufficient work to keep 

 the tractor busy during the entire working periods. It will also be 

 noticed that the farms ol less than 480 acres show a greater percentage 

 of owners doing custom work than do those of larger size. 



Table XIX was prepared in order to ascertain what effect the size 

 of the farm had upon the results obtained from the tractor. The 

 figures used in its preparation are those furnished by tractor owners 

 in North Dakota who have used their outfits for two seasons. A 

 similar table for other States was not made because of the many types 

 of farming which would be represented, as it was believed the many 

 and varying factors involved would vitiate the results obtained. 

 In North Dakota, however, as has already been stated, the conditions 

 are very similar throughout the State, and the averages in the table 

 are believed to show the relation of the size of the farm to the results 

 obtained, as far as it is possible to do so. 



In this connection, attention is invited to the fact that there is a 

 close relation between the size of the tractor and the size of the farm, 

 the larger tractors usually being found on the large farms. In both 

 the tabulation by size of farm and by size of tractor, therefore, it is 

 impossible to determine to just what extent each of these factors 

 influences the result. 



From the table it would appear that slightly better results are being 

 obtained on the larger farms. It will be noticed that the percentage 

 of owners reporting that the tractor is a good investment is greatest 



