734 
Journal of Agricultural Research 
Vol. XXIII, No. 9 
interfered with. Clay has the finest particles, and accordingly it might 
have been expected to lose the most moisture. But the clay used in 
this experiment had been ground into powder in the laboratory, and 
the particles were so fine that the freedom of the movement of water 
was retarded and therefore evaporation was checked. 
Fig. 2 .—Diagram showing the loss of moisture due to absorption and capillarity, taking the total loss as 
ioo per cent. 
EVAPO-TRANSPIRATION RATIO AS AFFECTED BY MULCHING AND 
CULTIVATION 
In so far as mulching or cultivation has the power of preserving 
moisture in the soil, what effect do they have upon the transpiration of 
plants? Do the plants make use of the water economically with 
mulching or cultivation? 
The apparatus designed for this experiment consisted of a soil can 
with a water tank connected at the bottom. Water from the tank was 
allowed to run into the soil can, and it in turn was brought up to the 
surface by the capillary action of the soil. Measurements of the water 
surface were made twice a week by means of an evaporation gage 
