26 



BULLETTX 174, U. S. DEPARTMENT OF AGRICULTURE. 



DEPTH OF PLOWING. 



In order to ascertain whether plowing is usually deeper when 

 done by tractor than when done by horses, Tables XVI and XVII 

 were prepared. Table XVI shows the average depths of tractor 

 plowing in nine States for the number of seasons for which reliable 

 averages could be obtained. While the variations seem to be slight, 

 they are greater than would appear at first glance. Each depth 

 shown represents an average of a large number of reports, most of 

 which are, of course, close to the final average; therefore, in order 

 to increase or diminish the final average even one-tenth of an inch 

 requires a general increase or decrease in the individual reports. 



Table XVI. — Average depth of tractor plowing on farms in various States. 





Average depths reported (inches). 



State. 



Average depths reported(inches). 



State. 



First 

 season. 



Second 

 season. 



Third 

 season. 



Fourth 

 season. 



First 

 season. 



Second 

 season. 



Third 

 season. 



Fourth 



season. 





6.18 



6.47 

 6.30 

 6.21 

 6.19 



5.88 

 6.44 

 6.47 

 5.87 

 6.17 



6.14 

 6.57 

 6.50 

 5.55 

 6.09 



6.11 



6.58 





6. 35 

 6.85 

 6.71 

 6.19 



6.42 

 6.77 

 6.02 







South Dakota. . . 



California 



Nebraska 



Texas 













































The distribution of the individual reports for all States west of 

 the Mississippi River is shown in Table XVII. The concentration 

 of the reports on the 5, 6, and 7 inch depths will be seen. The 

 reports for' the second season show a decided decrease in the percent- 

 age reporting 7 inches or more, with a corresponding increase for 

 6 inches or less. In the third and fourth seasons there appears to 

 be a gradual return to the greater depths, but. in connection there- 

 with it must be borne in mind that the men who have used tractors 

 for three or four seasons have been the most efficient operators; in 

 fact, they are the survival of the fittest, for the first two seasons 

 serve to eliminate many of the inefficient operators, as well as many 

 of the defective outfits. 



Table XVII. — Percentage of tractor plowing done at various depths on farms in all States 

 west of the Mississippi River. 



■ 



Depth of plow- 

 ing. 



First 

 season. 



Second Third 

 season, season. 



Fourth 



and 

 subse- 

 quent 

 seasons. 



Depth of plowing. 



First Second 

 season, season. 



Third 

 season. 



Fourth 



and 

 subse- 

 quent 



seasons. 





3.84 

 16.85 



4.94 | 5.17 

 23.51 ! 20.34 

 41. 66 i 36. 55 

 IS. 72 20.34 



5.94 



14.61 

 41.10 

 21.46 





1 

 11.54 ! 7.84 

 2. 72 1. 60 

 2.04 1 



11.72 

 3.45 



8.22 







.91 



6 inches 



7 inches 



37.22 

 24. 32 



10 inches 



5.94 







