22 



SOILS AND PLANT LIFE 



To study the effect on the rise of water in the soil of 

 discing stubble or trashy ground before plowing. 



Procedure. — Fasten cheesecloth firmly over the lower 

 end of chimneys or glass cylinders as you did in Exercises 

 4 and 8. Fill the first chimney full of fine, sifted soil. 

 Fill the second one two thirds full of the same soil, then 

 add a small handful of fine clods, then soil again until the 

 chimney is full. Fill the third chimney exactly as you 



Fig. 7. — Farmer discing. 



Courtesy Iowa Stale College. 



filled the second, only substitute a half inch of fine straw 

 for the clods. Fill a fourth chimnej- as you did the 

 third, but instead of putting the straw in a layer, cut and 

 mix it thoroughly with the soil in the upper part of the 

 chimney. Note that while the straw in the third chimney 

 is in a layer, just as it would be if we plowed stubble 

 without discing, that in the fourth chimney is mixed with 

 the soil just as it is when stubble is disced before plowing. 



