142 SOIL MANAGEMENT 



The growth of the "age of steam" made possible still 

 further development in the plow. To-day, on large farms 

 free from stumps and stones, the 110 horse-power trac- 

 tion plow moves as fast as a man can walk, covering a 

 strip 30 feet wide at one time. This machine plows, 

 harrows, and seeds at the same time, and treats 80 or 100 

 acres a day. 



94. In plowing, we must consider the depth, the time, and 

 the manner of turning the furrow. 



TRACTION PLOW AND DISK HARROW. 

 Note the width of land plowed and harrowed by. one man. 



a. Depth. It pays to plow deep. Said a wise man to 

 a farmer who complained that his land was poor: " There 

 is much wealth in the farm under the one you have been 

 tilling : plow up that wealth." 



It will not do, however, to bring up a large amount of 

 new subsoil at any one plowing, because that undersoil lacks 

 humus and cannot get much of its plant food into available 

 forms in the first season it is tilled. About one inch 

 deeper than previous plowings is as deep as the plow 

 should go at one plowing. Deep plowing should be secured 

 gradually. 



Deep plowing is especially necessary in dry regions and 



