4 
Bulletin 103. 
All deep plowing is best done in the summer or fall. This 
permits the weathering of the soil, through the fall and winter, 
making its mechanical texture more desirable and the plant food 
available. Deep plowing assists water to percolate or pass through 
to lower depths. Hence it increases the water holding capacity of 
the soil, a most important element in semi-arid farming. The 
deeper the plowing the greater the soil reservoir. Experiments con¬ 
ducted at the Cornell Experiment Station, New York, by Dr. Rob¬ 
erts show that an acre of average soil in good tilth will hold 20 to 
25 per cent of moisture and not be too moist for cultivation. It is 
estimated that an acre of soil 12 inches deep will weigh 1,800 tons if 
it contains 20 per cent of moisture, 1,620 tons if it contains 8 per 
cent of moisture—the amount upon which plants are able to grow 
and maintain themselves. Dr. Roberts says that an inch of rainfall 
brings to each acre 113 7-16 tons of water. If this could all be 
retained in average soil it would mean almost 7 3-5 per cent moist¬ 
ure, nearly enough to maintain plant growth. Well fined soil is 
capable of taking up two inches of rainfall in the first foot of soil 
and still be in good condition to cultivate. Suppose that this soil is 
deeply plowed and contains 15 per cent moisture; an inch or a two- 
inch rain would find the soil reservoir able to hold it. If this 
ground were shallow plowed, say four inches, an inch rain would 
saturate the reservoir, while a two-inch rain would overflow the 
soil reservoir, causing a loss of water and severe washing away of 
the surface soil. Deep plowing therefore increases the storage ca¬ 
pacity of moisture in our soils from which the plant draws as it 
has need. 
Good plowing gives a clean-cut.furrow on side and bottom. It 
turns the inverted furrow slice upon edge in a moderately well 
pulverized condition with but few air spaces at the bottom edge of 
the furrow slice. A good coulter lessens draft and aids in making 
a clean cut furrow. Disking the ground before plowing is advant¬ 
ageous but increases the expense of preparing the seed bed. 
A seed bed from one to three inches deep can be prepared with¬ 
out plowing. The young plants may grow sturdily at first, but if the 
soil is not in a physical condition to store the moisture necessary to 
dissolve the plant food and render it available for the growing plant, 
lack of nourishment will bring it to an untimely end and the crop 
will prove a failure. Very successful crops are grown this way, 
when the moisture is supplied by ditch or sub-irrigation but it is 
always hazardous to attempt cropping without thorough tillage, 
under semi-arid conditions. 
A disc plow will often leave the soil in a good condition for 
the harrow, when the ground is too hard for a mold board plow to 
do satisfactory work. The drier the ground the more narrow 
