210 Moisture Equilibrium [408 



as possible, the other as far removed as possible. The aver- 

 age of the two was taken to be representative of the entire 

 soil mass. Each sample was removed and dried in eight 

 2-cm. sections, so that it was possible to study both the ver- 

 tical and horizontal distribution of the soil moisture in the 

 cylinder. There was a horizontal as well as a vertical varia- 

 tion of small magnitude in the soil-moisture content of 

 all the cylinders, the water content being almost always 

 somewhat higher near the cups and at the bottom of the soil 

 mass. The distribution of the moisture, both horizontal 

 and vertical, was more uniform in the sand-loam mixture 

 than in the sand, and also more uniform in the loam than 

 in the mixture. The number of porous cups used had very 

 little influence, if any, upon the soil moisture content of the 

 loam; it varied as 100 : 106 : 103, for the containers having 

 one, three and five porous cups, respectively. This influence 

 of the number of cups was more pronounced in the case of 

 the sand-loam mixture, the variation, with one, three and 

 five cups, being 100 : 147 : 168. With the sand there was a 

 still more marked effect, the moisture contents for the three 

 cup numbers being 100 : 191 : 277 in this case. These vari- 

 ations are all smaller than the corresponding variation? in 

 the value of the ratio of cup number to soil mass, these values 

 varying as 100 : 321 : 576, for all three soils. For the con- 

 tainers with three cups the actual average soil moisture con- 

 tent (on the basis of dry weight) was 11.0 per cent, for the 

 loam, 5.2 per cent, for the mixture, and 1.1 per cent, for the 

 sand. 



With the pressure here used (averaging 5.5 cm. of a mer- 

 cury column) the soil moisture content at equilibrium was 

 too low for plant cultures in the sand and perhaps also in the 

 sand-loam mixture. In the loam, however, it was surely high 

 enough to supply plants with the water necessary for their 

 growth under ordinary greenhouse conditions. 



