[413] SCIENTIFIC MANUAL. 127 



colate freely to the depth of the drain, and prevents the loss 

 of heat incident to the slow evaporation of water stagnated 

 in the soil or subsoil. 



6. It carries down to the roots of plants soluble plant- food, 

 that would, without the drainage, be carried off in surface- 

 water to the gullies and streams. 



Liquid barnyard 'manure, filtered through clay, comes 

 out deprived of all coloring matters. Rain water absorbs 

 fertilizing gases from the air during its descent, and takes up 

 soluble matters from the surface, and carries them into the 

 soil, where they are absorbed and retained for the use of 

 plants. 



7. \^. prevents the winter- killing of small grain, by carry- 

 ing off the surplus water, which would otherwise saturate 

 the surface soil, freeze, and break the roots of the plants. 



8. It prevents tJie injurious effects of drouth, by affording a 

 deeper range for the roots, and thus removing them from 

 the influence of sudden changes of season. It prevents 

 injury from drouth, also, by admitting a free circulation of 

 air, from which moisture is condensed and absorbed by the 

 fine particles of the soil. 



9. It increases the effects of manures, by admitting their 

 more uniform distribution through the soil, preventing 

 their parching effects in periods of drouth, and the leaching 

 influence of stagnant water and surface drainage, occasioned 

 by excessive rains on undrained lands. As a result of tliis 

 and other circumstances, it improves the quality and in- 

 creases the quantity of the crops produced. 



The most important question to be considered and de- 

 termined by individuals, after a full consideration of sur- 

 rounding circumstances, is, 



WILL DRAINAGE PAY ? 



Not only individual, but general experience, in the coun- 

 tries that have most generally adopted underdrainage, in 

 both field and garden, answers this question in the affirma- 

 tive. It is stated that the crops of England have been 

 doubled by drainage, and the results, as far as it has been 



