Draft of Plows. 



243 



303. Draft of Stubble Plows. The amount of labor in- 

 volved in plowing a field is so large under the best possible 

 conditions, and it is so easy to make it unnecessarily large, 

 that it is important to understand the principles upon 

 which the draft depends. 



Mr. Pusey in England, in 1840, made a series of trials 

 on the draft of plows in soils of different kinds, using 10 

 different plows. We have combined his results and give 

 them in the table below: 



Table showing the draft of plows in tests made in England 

 and in America. 



Prof. J. W. Sanborn made an extended series of trials in 

 1890 in Missouri and later in Utah and the average of all 

 his trials gives a draft of 5.98 Ibs. per sq. inch of the cross 

 section of the furrow slice. Separating these trials historic- 

 ally, omitting those in the blue clay in England, ih<> re- 

 suite stand: 



English trials 1840, mean draft 7.41 Ibs per aq. Inch. 

 American trials 1850, " " 5.81 " " " 



" " 1890, " " 5.98 " 



304. Draft of Sod Plow With and Without Coulter. A 

 set of trials with a sod plow near the type of Fig. 77, in 

 clover sod 2 years old,when the moisture present was about 

 as high as it is prudent to work the soil, gave results as fol- 

 lows: 



