TENTH ANNUAL YEAR BOOK— PART X 563 



ish the plants, but when it falls on an undrainetl soil it diminishes the- 

 amount of oxygen and produces injury to the plants, by an excessive 

 amount of stagnant water and by lowering the temperature of the soil, 

 for a longer period than is consistent with the health of the plant. No 

 fear need be entertained that any clayey or loamy soil can be over- 

 drained, or, in other words, that so much moisture may be drained out 

 of the soils as not to leave sufficient moisture remaining for the use of 

 any plants which may appropriately be grown in the soil. All soils have 

 what is known as capillary attraction — that is, the power to suck up 

 moisture and mineral matters in solution, and the finer the soil the 

 stronger the capillary attraction. 



The coarser pores of the soil can not be filled with water, unless these 

 are impediments prohibiting the water from following its gravity thus in 

 an arable soil only when it is resting on impervious stratum; but in a 

 properly drained soil the water descends regularly. 



Drainage removes stagnant water from the surface. On an undrained 

 soil the water becomes stagnant because the pores are already filled with 

 water which has no means of escape other than evaporation. 



Furnish undercurrents for the water by means of drains and there 

 is no longer any reason for the water to remain above ground, until it 

 becomes changed from a healthful to a poisonous substance by the con- 

 tinued action of heat and atmospheric air upon it. 



Chemists assert that fully four times the amount of heat is required 

 to convert water into vapor that is required to bring it to the boiling 

 from the freezing point. It is no uncommon occurrence that rain to the 

 depth of one inch falls in the course of a shower. This amount falling on 

 a single acre would amount to 360 hogsheads, and to evaporate this 

 amount of water by sunshine would require an amount of heat that 

 would convert upward of 1,500 hogsheads of water from the freezing to 

 the boiling point. Every one must know that this evaporation is a very 

 slow process and while it is going on the soil is kept wet and cold; that 

 vegetation is retarded, if not entirely checked, in the early springtime. 



Now, if these 1,500 hogsheads of water were carried off in drains this 

 great amount of heat necessary to evaporate this water would be saved 

 for the warming of the soil. Among the other advantages of drainage 

 over evaporation may be the following: 



In undrained ground the season of growth is shortened by the time 

 occupied in evaporation. 



In undrained ground the water, passing off in vapor, carries with it 

 certain quantity of the latent heat of the earth, and this heat is in propor- 

 tion to the amount of vapor formed. Thus the land is colder than it was 

 when covered with water. In evaporation, organic mineral matters, in 

 the form of gases, pass off with the vapor, thus leaving the ground poorer. 

 Undrained lands suffer from hot or dry weather, though there may be 

 water within a few inches of the surface, the ground is so compact and 

 baked that it is not sufficiently porous to draw moisture. 



In winter and spring v/et land heaves under the influence of frost 

 and heat, thus exposing such grains as have been planted, directly to the 

 weather. 



