98 HANDY-BOOK OF HUSBANDRY. 



sufficient nutriment in the soil, unless arrested by their coming in 

 contact with a cold, wet, uncongenial subsoil. By withdrawing 

 the moisture which causes this unfavorable condition of the sub- 

 soil, we may maintain a full supply of grass plants, as long as we 

 can keep the soil rich enough to support them. 



7. It deepens the surface soil. The withdrawal of the water 

 which, in undrained lands, occupies the subsoil for so great a por- 

 tion of the growing season, allows the roots of plants to extend 

 much farther from the surface, and in decay, these roots deposit 

 carbon (black mould) in the spaces of the lower soil, while the 

 mineral parts are improved by the action of the air, thus, 

 gradually, converting the subsoil to the condition of the surface 

 soil. 



8. It renders soils earlier in the springy and keeps off the effects of 

 cold weather longer in the fall ; because the water, which renders 

 them cold, heavy, and untillable, is earlier removed, and the excess 

 of water, which produces an unfertile condition on the first 

 approach of cold weather, is withdrawn. 



9. // prevents the throwing out of grain in winter ; because the 

 water of rains is at once removed, instead of remaining to throw 

 up the surface by freezing, as it does by reason of the vertical 

 position taken by the particles of ice. 



10. It enables us to work much sooner after rains , inasmuch as 

 the water will pass down to the level of the drains much sooner 

 than it will soak away in an undrained, retentive soil, or be 

 removed by slow evaporation from the surface of the ground. 



11. // prevents land from becoming sour ; because the acids which 

 result from the decay of organic matter, in the presence of too 

 much moisture, are not formed in the more healthy decomposition 

 which takes place in a sufficiently dry and well-aerated soil. 



12. // lessens the formation of a crust on the surface of the soil after 

 rains in hot weather. When water, having mineral matters in 

 solution, is drawn up from the lower soil, it deposits them, at the 

 point of evaporation, at the surface, often forming a hard crust, 

 which is a complete shield, to prevent the admission of air with 

 its fertilizing gases and water vapor. In proportion to the com- 



