ESSAY ON DEEP TILLING. 123 



sooner find the rich loam and manure intermingled deeply with the 

 soil. The leaching process, as it is called, is reversed, and takes 

 place upwards more than at any other time, or in more scientific 

 phrase, capillary attraction is increased. As each particle of 

 moisture is evaporated from the surface it is succeeded by another, 

 and the whole soil is filled with the ascending moisture and gasses, 

 which are appropriated by the numerous rootlets as they have need. 



The wet season is also a blessing to the deep cultivator. The 

 more rain, the more heat, ammonia, carbonic acid and other organic 

 elements are left in the soil as it descends. As each drop filters 

 through, it is succeeded by another, or by air, both essential to 

 vegetation ; and to dissolve, act on, or combine with, the inorganic 

 elements of the soil. As the water drains off, air is sure to follow, 

 and this is the proper mode of its circulation. Each is also gener- 

 ally at a higher temperature than the undrained land, and the 

 warmth of the under soil is therefore relatively increased. The 

 farmer often objects to this waste of water and would fain retain 

 it for a dry time ! The trenched and porous soil holds water like a 

 sponge, notwithstanding the drainage. It retains or can command 

 enough for the wants of vegetation. But let us see the operation 

 on the undrained land. 



The farmer often speaks of his " cold wet land." No variety of 

 soil, in any location, is, of itself, colder than another. The very 

 water which trenching, draining, &c., allow to pass off after imparting 

 its virtues to the soil, if retained on or near the surface by hard 

 impervious sub-soil, becomes itself, by its changes, the source of the 

 coldness complained of. Instead of running off, it evaporates, and 

 by this process abstracts a great quantity of heat from the soil and 

 surrounding atmosphere. The evaporation of a pound of Avater 

 requires about 1000° of heat. Some authors stating it less and 

 others more. Or it reduces 100 pounds of air 45^^. This is 

 reversing the experiment of Prof. Johnson in Espy's " Book of 

 Storms," where he says " a pound of vapor" condensed to water 

 •' would heat 100 pounds of air about 45°." The ground to a 

 considerable depth is warmer, by many degrees, where the rain is 

 drained off instead of being allowed to accumulate and evaporate. 

 Hence this enormous loss of an invaluable stimulus to vegetation. 



This chilling and deadly process of evaporation is going on to 

 excess from the time frost comes out of the ground in the Spring, 



