WATER IN SOILS 



Evapm-aMon of Water from Hard Soils. 



15 



May 23 and 24 were cloudy days, the latter being very 

 humid, as a result of which the weight of the clay and loess 

 increased. When each soil became air dry it was heated in an 

 oven for 24 hours at 250° C. The sand when air dry contained 

 no measurable amount of water. The other soils contained 

 water as follows: loam 4 grams, loess 7 grams, saline 3 

 grams, clay 6 grams, humus 5 grams. The sand lost its 

 water most rapidly; the humus retained moisture most 

 tenaciously. 



From the foregoing data it is easily inferred that sandy 

 soils lose water by evaporation more rapidly than clay soils 

 and for this reason a plant must die more quickly in a sandy 

 soil than in one containing an excess of clay. Since the 

 plant is directly dependent upon the soil for its water sup- 

 ply, in times of drought the tenacity with which a soil holds 

 water is a matter of utmost importance in the economy of 

 the plant. The quality at once becomes of the greatest sig- 

 nificance in the consideration of the factors which control 

 the limit of water available for the use of the plant. 



