WHY SHOULD LAND BE DRAINED? 377 



Temperature. 



The temperature of the soil is a matter of the utmost 

 consequence. Seeds cannot germinate, and plants cannot 

 grow without there being a certain amount of heat in the 

 soil, and there is no means by which this heat is so much 

 and so constantly reduced as by the evaporation of water 

 from its surface. In proportion as we remove by the means 

 of under-draining the water which would, if not so removed, 

 remain to be evaporated, we allow the soil to attain a 

 higher temperature, and so to become more productive. 



The penetration of roots. 



In a soil that is usually too wet, the roots of plants con- 

 line their operations to the few inches of dry soil at the 

 surface, as they will not push into a cold, compact, wet sub- 

 soil. Draining removes the water from the subsoil, allows 

 it to become sweet and warm and loose, and fit for the 

 entrance of roots, which are thereby enabled to seek farther 

 for a greater quantity and a greater variety of food. 



The circulation of air. 



Atmospheric air, if not absolutely necessary to the life 

 and action of the roots of plants, greatly favors their growth 

 and their absorption of food. Aside from its direct supply 

 of carbonic acid to the feeding parts of the roots, it brings 

 moisture to the soil by which they are surrounded, and aids 

 in preparing its nutrient constituents for assimilation. 



