186 CAMPBELL'S SOIL CULTURE MANUAL 



light, then when it gets to the proper stage for growth, a 

 new set of roots form just at the point where air, moisture, 

 and heat seem to mingle in the most ideal quantities. Here 

 the complete system of feeding roots is established and the 

 root or stem from there down to the kernel withers and' 

 dies. 



What is here shown regarding wheat is also true of all 

 other grains, corn included. One of the main points we 

 wish to establish here is that depth of seeding does not 

 establish the depth of rooting. 



HARROWING SPRING WHEAT 



The harrowing of spring wheat is not today a common 

 practice. Some wheat' growers have never heard it agi- 

 tated, but more do not believe it can be done without 

 causing a permanent damage to the crop; and yet we have 

 noted and watched results where a part of a field was 

 harrowed and a part left unharrowed, when the final yield 

 would show more than double where it was harrowed than 

 where it was not harrowed. 



The harrowing of wheat and all other small grain is a 

 subject, of vital importance, but like all other branches of 

 soil culture there is a right and a wrong condition, a right 

 and a wrong time, a right and a wrong manner of harrow- 

 ing. 



SOIL CONDITIONS 



The first condition to consider is the soil condition. 

 Just a glance at cut No. 16. The soil at what we term the 

 root bed is here shown fine and firm. Note the root sys- 

 tem. In case of a heavy rain that would dissolve and 

 settle the loose mulch, thereby assisting the loss of our 

 stored water below, as well as shutting the air out. Some- 

 thing must be done. Just as soon as the surface is suffi- 

 ciently dry so the soil will not stick to the harrow this 



