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Causes of Fertility or Barrenness of Soils. 
an animal to exist without food, if placed in a good atmosphere, 
as a plant to live without moisture. The amount of cohesiveness 
necessary for fertility depends upon climatic influences — a point 
too often lost sight of in agricultural examinations, since the rain- 
fall varies in this country from 18 to upwards of 70 inches per 
annum. In a climate constantly moist much less retentive power 
would be necessary than in a dry air, where not one-third so much 
rain falls, and where consequently the soil must act as a reservoir. 
Limestone soils are often remarkably fertile in the former situ- 
ations, whereas in the latter they are often poor, and readily 
affected by drought. 
The fineness or coarseness of granulation of soils is another 
mechanical character of considerable importance. Fine soils 
retain moisture longer than coarse ones, probably because they 
offer greater obstruction to its passing away, and possess a higher 
capillary power. By this term we refer to the power water 
possesses of rising in the soil, apparently in opposition to the 
laws of gravitation. If we take a fine tube of glass and place the 
bottom end in water, the water Avill rise in it to a considerable 
height, standing highest at those points where it touclies the glass, 
as though the water possessed a certain attraction for the glass and 
scrambled up by laying hold of the sides. The finer the tube 
the greater the capillary attraction. We must, therefore, regard 
the soil as consisting of a number of tubes, the walls formed by 
the particles of soil, and the hollow represented by the natural 
space between them. We must not confound this gradual rising 
of water with the rising of springs, as the latter results from the 
pressure of accumulated volume, which tends to force the water 
upwards till it reaches its former level. In dry seasons and 
climates the capillary power of a soil is often of great importance, 
as a steady supply of moisture is thus afforded to the roots long 
after the surface has become dried up. One of the great objects 
of draining is to prevent excessive capillarity by drawing off those 
waters, which would otherwise find their way to the surface in too 
great quantities, and lower the temperature of the soil by evapo- 
ration. Peaty soils possess considerable capillary powers ; but 
clay surpasses all other soils in this respect. Limestone soils and 
coarse sands, being composed of larger materials, have little 
capillarity. Fine soils, being much firmer than coarse ones, 
present a better surface for the roots to attach themselves. The 
presence of considerable quantities of loose stones or flints in the 
latter often has a beneficial effect, in rendering them more solid, 
preventing the roots being thrown out by frost, sheltering the 
young plant, and shading the ground from the drying effects of a 
hot sun. The custom of picking off all stones from the surface 
is often a great error, as they exercise a beneficial influence, and 
