256 DRY FARMING 



by seed and can be controlled only by plowing. Plow- 

 ing in a dry time is more effective than plowing in a wet 

 season. To kill these plants in prairie sod it is often 

 necessary to plow twice, or to "break and backset". To 

 kill them when present in stubble fields either of two 

 methods may be used : (1) fall plow and leave loose over 

 winter, or (2) spring plow and sow thickly at once to 

 a leafy crop like oats or barley. If present in land to be 

 fallowed two plowings are advisable — shallow in fall 

 and deep the following summer or shallow in late spring 

 and deeper in late summer. 



206. Plowing When the Soil is Too Wet or Too Dry.— 

 When a soil is plow^ed when either too wet or too dry its 

 physical condition may be seriously injured. The dam- 

 age resulting from such a cause can seldom be remedied 

 by tillage and is frequently not repaired by the weather- 

 ing agencies until it is too late to get a good crop. It is 

 true that many heavy soils when left in this condition 

 "slake down" after rains and after the low tempera- 

 tures and snows of winter ; but some do not, and often 

 the rains and snows of winter are very scarce and fail 

 to accomplish the leavening influence of normal or wet 

 seasons. 



This injury is seldom serious on fallowed fields that 

 are too wet or too dry when plowed for the reason that 

 the weathering agencies have time to either partially or 

 wholly repair the injury done by man in his untimely 

 operations. Medium and light types of soil seldom suf- 

 fer serious physical injury from this cause but heavy 

 loams and clays frequently do. On some of the heavier 

 soils in the drier parts fall plowing that is done when 

 too dry turns up in chunks and dries out and often can- 

 not be worked down well enough to give good results 



