PLOW BOTTOMS tbl 



Special plows are required for this purpose. The 

 shape of the share and mouldboard is such that the 

 furrow is turned over disturbing its composition as 

 little as possible. Illustration E shows this type of 

 mouldboard. 



The other influencing factor in reference to shapes of 

 mouldboards is sticky soils that do not have enough 

 body to hold together to give the amount of pressure 

 necessary to force the dirt off the mouldboard. Natur- 

 ally, in designing plows for work in this type of soil the 

 mouldboards and shares are designed to crumble the 

 soil as little as possible. The curvature is less pro- 

 nounced than in any other type of plow bottom. 



There are various ways of explaining the crumbling 

 and crushing influences upon the earth as it passes over 

 the mouldboard, but a very simple explanation is found 

 in observing the distance that the top and bottom of the 

 furrow slice travel in the process of being picked up and 

 turned over. 



It is obvious that the bottom of the furrow slice 

 travels a much longer distance when being inverted than 

 the top or stubble side. This process of inverting the 

 furrow means breaking up the earth into particles. 

 Whether these particles are broken into larger or 

 smaller clods depends upon the tenacity with which they 

 stick together andj^the shape of the mouldboard for 

 pulverizing. 



The broad principle employed in shaping the curva- 

 ture of mouldboards is one that will cause the soil 

 granules to roll one upon another and thus break their 

 cohesion. A closely textured soil, plowed while wet, 

 increases the cohesions of the granules so that they will 

 not fall apart in the act of plowing. Thus a mouldboard 



