120 THE BOOK OF CORN 



If from any reason this supply of water is cut off 

 the plant dies, or if the water is supplied in insufficient 

 quantities the plant suffers accordingly, so that it is 

 one object of cultivation to conserve the greatest possi- 

 ble amount of moisture in the soil for use by the plants 

 and to allow of the greatest possible development of the 

 root system of the plants. 



Shallow Cultivation — In general, shallow or sur- 

 face cultivation frequently performed, conserves more 

 moisture than a smaller number of shallow cultiva- 

 tions. On the other hand, an equal number of deep 

 cultivations will likely conserve more moisture than 

 shallow cultivations. By a careful series of tests at 

 the Illinois experiment station this fact was conclu- 

 sively demonstrated. However, the shallow cultiva- 

 tions uniformly give the largest yields. This loss in 

 yield in the deep cultivations was undoubtedly not due 

 to less moisture, but to injury to the root system by the 

 cultivation. For instance, it was found that by pruning 

 the roots of the corn plants to different depths during 

 three years of experimentation that the yield was uni- 

 formly smaller the deeper the root pruning. 



Root Pruning — The more roots cut off the smaller 

 the yield. In the cases of the plants, the roots of 

 which were pruned, it was found that after pruning 

 the plants drooped, the leaves rolled up, giving every 

 indication of injury due to lack of sufficient soil mois- 

 ture. The plants were stunted and never recovered 

 their vitality, but matured earlier than the plants not 

 pruned, although otherwise grown under similar 

 conditions. See Fig 54. 



Effect of Weeds on Crop — The point of second 

 importance in corn cultivation is the removal of the 

 weeds. If weeds of any kind are allowed to grow in 

 the cornfield, they use the same elements of fertility as 

 the corn plants, consequently they compete with the 



