SOIL WATER AND SOIL AIR 21 



not furnish a sufficient supply of water to germinate the seeds 

 that have been planted. In such cases the soil particles are 

 too far apart to allow capillary water to reach the seeds. 

 Here the problem is how to restore the capillary action so as 

 to bring water from below in sufficient quantities to secure 

 germination. This may be accomplished by forcing together 

 the particles near the surface, by the use of a roller or by 

 similar means. The broad wheels of a corn planter following, 

 as they do, the grains of corn dropped before them, serve to 

 pack or firm the soil at each hill. This establishes the capil- 

 lary current, bringing the water where it is needed for germi- 



Effect of compacting soil. (Cornell Agr. Exp. Station.) 



nation. As soon as the firming of the soil has served its 

 purpose, that is, when the seeds have germinated, the mulch 

 should be restored; otherwise there will be a loss of water 

 by evaporation which will offset the gain of quick germi- 

 nation. 



How water may be controlled by drainage. Drainage is 

 an important means of controlling soil water, especially, in 

 heavy soils. The condition of the soil which often occurs 

 in early spring has already been described. Here the free 

 water interferes with working the soil by making it difficult 

 or impossible to handle. It also interferes with the early 

 development of the plants by keeping the soil cold, thereby 

 preventing the rapid growth of the young plants as well as 



