48 CAMPBELL'S SOIL CULTURE MANUAL 



have a direct effect upon the final yield of the crops. First 

 of all, it cuts off the seed or root bed from the sub-soil, 

 preventing the movement of any moisture up into the 

 root-bed. It also forms air spaces or cavities where a 

 volume of air may exist, which aids in drying out the 

 soil immediately adjacent. It also prevents the lateral 

 roots and feeders from extending and permeating 

 this portion of the soil, leaving a large per cent of our 

 surface soil in a condition riot at all beneficial to the grow- 

 ing crop. 



In cut No. 3, we show the cross section of the same 

 two furrows shown in cut No. 1. Here the cavities and 

 loose condition of the soil at the bottom of the furrow 

 have all been obliterated by the use of the sub-surface 

 packer, which is illustrated in cut No. 5. These sharp 

 wedge-faced wheels have both a downward and a lateral 

 pressure against the soil in the spaces between them. 

 The soil is moved by the packer in such a manner as to 

 form a firm and evenly packed stratum at the lower por- 

 tion of the furrow. 



EFFECT OF THE DISKING. 



A word about the disk. Had this land been double- 

 disked before plowing, the stubble, weeds or manure 

 shown in a strip at the bottom would have been scattered 

 through the lower part of the furrow, the soil made finer 

 and the packer would have made it more uniform and 

 firmer, increasing its water-holding capacity. This would 

 have promoted more general nitrification, facilitated greater 

 and more uniform root growth and made it possible to 

 have even doubled the yield of the crop, for it is not un- 

 common that a little more available fertility just tit the 

 proper time would have increased the yield fully two 

 and possibly three times. 



