THE PRINCIPLES OF TILLAGE 



109 



and stubble plows of many patterns. Each of these 

 may be fitted with coulters, jointers and weed rods or 

 drag chains, and the coulters may be "rolling", "knife" 



Fig. 37b. Subsoil Attachment on Mouldboard Plow. 



or "fin". But all are plows and all have the same 

 functions. 



The Pulverizing Action of the Mouldboard Plow. 

 Just how the mouldboard plow pulverizes the soil is 

 well illustrated by King (Fig. 38A). If one takes a 

 paper-covered book and bends it Abruptly as when 

 about to scan its pages rapidly, it will give him some 

 idea of what happens to the soil as it passes up over the 

 mouldboard of a stubble plow. The relative change in 

 position of the particles in the furrow slice is shown 

 by comparing the line 3-3 before the soil is pulverized 

 with the line 1-1 after it has passed the slope of the 

 mouldboard. 



