140 SOIL MANAGEMENT 



concern the preparation of the soil and its care while the 

 crop is growing. 



92. The plow has often been called the most important 

 instrument ever invented. Its pictures decorate the 

 coat of arms of many of our states. Two great classes of 

 plows are now in use: 



a. The disk plow has a rolling motion, and is used 

 mainly in dry soil. 



b. The moldboard plow slides along through the ground. 

 By varying the shape and slope of the moldboard, we get 

 varieties of this kind of plow, the stubble plow, the 



THE COMMON PLOW. 

 Here the plowman walks behind. 



breaking plow, the black-land plow, and so on. These 

 varieties are used for the purposes that their names 

 indicate. 



93. Stages of the Plow. In very early times, and in some 

 backward countries to this day, the plow was literally a 

 crude tree crotch, which was drawn by slaves or cattle. It 

 took centuries to make the improvements that are now so 

 well known. The iron share, in some form, must have 

 been in existence 1100 years B.C., because the Bible 

 relates that the Israelites went down to the Philistines 

 " to sharpen, every man, his share and coulter." About 

 1800 A.D. the cast-iron plow appeared; but farmers long 



