20 



MANUAL FOR SUGAR GROWERS. 



and an equal quantity of water added to eacli ; the 

 two tins and their contents are now precisely alike 

 in weight and other conditions ; one is left thus, but 

 the contents of tlie other are closely pressed together, 

 so as to imitate the condition of a badly tilled soil. 

 The two tins are now exposed to the sun for several 

 hours, care being taken that the conditions of ex- 

 posure are equal ; after a time they are carefully 

 weighed to ascertain the quantity of water lost by 

 evaporation. It will be found that the porous soil 

 loses moisture much less rapidly than the other. 

 The following results were obtained by the author 

 in an experiment conducted as described : 



Two Tins, each containing 694 Grammes of Air-dried 

 Soil and 100 Grammes Water. 



Loose soil. 



Loss 1st day . . 

 Loss 2d day. . . 

 Loss 3d day. . . 



Loss in 3 days 



19 grammes 

 10 



7 



36 



The loose soil at the end of three days has twelve 

 and a half per cent, more moisture than the com- 

 pact one. 



It must also be remembered that in tropical and 

 sub-tropical climates, during a period of drought, 

 heavy dews are not uncommon ; if the soil is porous 

 a certain amount of moisture in the form of dew will 

 be deposited in the soil itself, thus assisting plant- 

 life at a critical time. 



That a porous soil parts with its surplus water 



