HINTS ON SOILS AND FERTILIZERS 35 
tion, which is generally towards the top sur¬ 
face. As a result, the capillary moisture film 
of water, which surrounds each soil particle, 
keeps climbing up from one soil particle to an¬ 
other in an effort to reach the dry section. - 
But as soon as it reaches the dry soil particles, 
it may either be absorbed by the rootlets of 
some plant, or, if cultivation is lacking, it will 
be evaporated off from the surface of the soil. 
Thus it will be seen that the plant can continue 
to grow for quite a long period of time despite 
the lack of rain, if there is a good supply of 
capillary moisture. 
This capillary action of soil water, as has 
been stated, is the source from which all plants 
receive their water, which in turn ca rry a weak 
solution of some of the soil elements. It has 
been shown that what moisture is not taken up 
by the plants will evaporate from the surface 
of the soil if conditions are favorable for this 
action. However, man has devised a way by 
which he prevents a large part of this loss of 
moisture. Man has found that if he stirs the 
surface soil, thereby breaking up the soil par¬ 
ticles so that these particles are too far apart 
for the capillary moisture to climb from one 
particle to another, this moisture will come up 
as far as the lower edge of the broken up sur¬ 
face, and remain there, not being able to climb 
to the very top, so that evaporation is thereby 
checked to a great extent. When the soil is 
thus stirred, we say that we have mulched the 
surface of the soil. This mulch, to state the 
matter in another way, is simply the top soil 
stirred up in such a manner that the soil par- 
