IMPORTANCE OF AIR IN SOIL 



31 



Observe how deeply fissures will penetrate the ground when conditions 

 are ripe. This condition can only be prevented by a mulch of earth on 

 the surface to keep moisture travelling upward from the ground water 

 level to the mulch, and the rays of heat and light from penetrating. 



Summing up the importance of air in the soil, temper- 

 ature and plant food development, and the killing of 

 insect pests we find that early summer plowing, with 

 complete burying of stubble and trash on the bottom 

 of the furrow, is the best method for killing the Hessian 

 fly, and aerating the soil at a time when nitrates develop 

 best. At this time there is the least amount of rainfall 

 to wash away plant food and the soil is in the best 

 possible condition for the percolating and saving of 

 what rain does fall so that later in the fall when the 

 time comes for planting wheat it is at a cooler temper- 

 ature with plant food enough developed for giving the 

 wheat a remarkably good start, thus lessening its 

 chances of winter killing. 



