CAMPBELL'S SOIL CULTURE MANUAL 59 



essary packing and at the right time. Elsewhere is de- 

 scribed more in detail the sub-surface packer especially 

 devised for doing this work, a machine which is winning 

 its way because of demonstration that it has a mission 

 to fulfill and is doing it. 



Sub-surface packing of the soil is a process of follow- 

 ing the plow immediately or otherwise with implements 

 which crush down the loose soil of the under portion of 

 the furrow slice, breaking up the large lumps, compact- 

 ing the whole so that the particles of soil lie closer together 

 and form a perfect connection between the unbroken 

 earth beneath the surface and the loosened soil of the 

 furrow. It is not compacting the surface layer as by 

 a roller, for that merely invites waste of the land as dust. 

 It has reference solely to that portion of the soil which 

 lies near the bottom of the cultivated upper soil. 



Nature has placed at the disposal of man all the nec- 

 essary conditions and elements in the sand loam soils 

 on the level prairies of the great semi-arid belt, together 

 with the properties of air and water, aided by heat and 

 light, to produce large crops every year, but has wisely 

 left it to man to work out the manner and method of 

 combining these elements; and it is now apparent that 

 the combining or utilizing of these elements must be upon 

 strictly scientific principles, or in plain English, there 

 must be correct principles under these ideal conditions 

 and every part of the work must be done precisely at 

 the proper time and in a correct manner. 



MISSION OF THE PACKER. 



The Sub-Surface Packer has a vital mission to per- 

 form. Its main object is not that of aiding in storing 

 the moisture in the soil, but that of controlling or equal- 

 izing the holding capacity of the soil for both air and water. 



