BREAKING THE VIRGIN PRAIRIE 131 



growth of these plants and to keep the soil from drying 

 out is essential after the sod has decayed sufficiently to 

 permit these implements to do good work. 



102. To Control Creeping-Rooted Grasses Break Early 

 and Backset. It has been pointed out that the primary 

 object of tilling prairie land is to kill the native vegeta- 

 tion and increase the moisture content of the soil. Un- 

 fortunately, the same practices do not always result in 

 accomplishing both purposes, since the drying out of the 

 furrow slice is the most effectual way to kill creeping- 

 rooted grasses. Under most conditions and in most years 

 both of these objects can be attained by breaking and 

 backsetting. Single plowing can be depended upon to 

 eradicate creeping-rooted grasses only if the district is 

 dry or if it is a dry year in a more moist area, or if it is 

 done late. 



The first crop after breaking and backsetting is often 

 not much larger than the first crop after deep breaking 

 that has been surface cultivated, but the second and 

 later crops are invariably better from the twice-plowed 

 land. In the year 1913, the second crop of wheat on land 

 that was broken and backset yielded 14 bushels, 36 

 pounds of wheat per acre, while the second crop on ad- 

 joining land that had been broken deep and surface 

 cultivated was but 4 bushels, 11 pounds per acre. The 

 difference was due altogether to the presence of native 

 quack grass in the once-plowed breaking. Single break- 

 ing and disking is less expensive than breaking and back- 

 setting, and when done in good time on soils free from 

 quack and sweet grass often gives as good results. Back- 

 setting in our opinion is advisable only in areas or on 

 soils where once-plowing does not ordinarily kill the 

 grass. 



