8 
GARDENING IN THE SOUTHWEST 
Moisture in 
Soil 
Capillary 
Movement 
from the 
Water Table 
Mulches 
HOW PLANTS EAT 
Since only a small percentage of a plant’s food is derived from 
the earth (approximately two per cent only) the major part 
being assimilated from the elements (water, heat, sun and air) it 
is very essential that correct soil conditions be maintained. An 
abundance of strength-giving properties may be present in the 
soil, yet not available for the plant’s use until they have been put 
into soluble form or released by the chemical action of organic 
matter. This latter is largely contributed by the use of barnyard 
manures, leguminous green manures, and commercially prepared 
fertilizers. 
MOISTURE 
The fertility of the soil is controlled to a great extent, also, by 
the amount of moisture it is capable of retaining, which, in turn, 
depends greatly on the composition and texture of the soil, itself, 
for each of its component grain-particles is, under usual circum¬ 
stances that support growth of vegetation, surrounded by a thin 
film of moisture. The larger these particles are, the less water they 
will retain, because the nature of loose soil does not admit of free¬ 
dom of capillary movement. 
Underlying almost all soils at varying depths is an accumulation 
of water, known as the "water-table”. From this reservoir an 
attraction of the film-water around the grain-particles of soil 
draws moisture up toward the surface, known as "capillary move¬ 
ment”. When the ground is left undisturbed, little tubes or "water- 
channels” are created, whereby moisture is the more rapidly 
brought to the surface and exhausted than when the soil is broken 
up by tillage (or frequent stirrings) which prevent these channels 
from forming. 
Chief among the other suggested methods for the conservation 
of moisture is mulching or surface covering with grass clippings 
that contain no grass-seed, straw, leaves, peat-moss, paper, saw¬ 
dust, etc., or in some cases, a surface-layer (from two to five 
inches) of very dry soil will act as a blanket to hold in the mois- 
