246 ELEMENTS OF AGRICULTURE 



case, the corn-field was gone over with a weeder before 

 the weeds were troublesome, just as they were coming up. 

 In the other case, the farmer waited until the weeds were 

 large enough to attract attention. It was then too late 

 to kill all of them. 



223. Subduing Land That Is Badly Infested with Weeds. 

 Some farms are so badly infested with weeds that special 

 treatment becomes necessary. Such land may be summer- 

 fallowed, that is, kept bare and tilled all one year. This 

 will usually subdue any weed, but often is not profitable, 

 as the season's crop is lost and the tillage is expensive, 

 There are several ways of conducting a short fallow with- 

 out the loss of a crop. The land may be plowed immediately 

 after harvesting a crop of hay or small grain, and be kept 

 stirred the remainder of the season; then grow a tilled 

 crop the following year. Such treatment will usually clean 

 the land fairly well. This short fallow may sometimes be 

 reversed. The land may be plowed in the fall or spring, 

 and be kept stirred until time to sow a crop, such as buck- 

 wheat or millet. The next year a tilled crop may be grown. 

 The tillage will kill many weeds, and such a crop as millet 

 will choke out weeds. 



224. Spraying for Wild Mustard. Nearly any soluble 

 chemical will kill plants if applied in strong solutions. 

 Even plant foods, such as nitrate of soda, will kill plants 

 if enough is applied. A solution may often be used that 

 is strong enough to kill certain weeds, and yet not strong 

 enough to harm certain crops. 



The most important application of this principle for 

 the control of weeds is in the case of wild mustard. This 

 plant is easily killed by spraying with a solution of iron 



