TILLAGE MACHINERY 63 



95. Types of plows' bottoms. The plow bottom, as 

 stated before, is_the plow proper, detached from the beam 

 or standard. Owing to the varying conditions under 

 which ground is to be plowed^ a few general types, each 

 with its own form of moldboard and share, have been 



established. These forms are illustrated in Fig-. 40, and 



L^*"**'^ ^""^ 



vary from No^7, me breaker, with its long- sloping, share 



moldboard, for natural sods, to No. i, the stubble 

 plow with short, abrupt moldboard for old ground. The 



FIG. 41 A STEEL WALKING PLOW WITH INTERCHANGEABLE MOLDBOARDS, 

 BY WHICH IT MAY BE MADE INTO A BREAKER OR STUBBLE PLOW 



intermediate forms are given the name of turf and 

 stubble, or general purpose, plows, being used for the sod 

 of trie cultivated grasses or for stubble ground. The 

 breaker is suitable for the native sods of the Western 

 prairies, as it turns the furrows very smoothly and covers 

 the vegetation completely, that it may decay quickly. 

 The abrupt curvature of the moldboard in the stubble 

 bottom causes the furrow slice to be broken and crumbled 

 in making the sharp turn, and thus has a more pulver- 

 izing action and is designed for old ground. The general 

 purpose plow is designed for the lighter sods, such as 

 those of the tame grasses. 



