to increase the lateness of a crop by encouraging
growth. The new wood of trees may not become hardy enough to withstand
the frost of winter if tillage is continued. Early maturity is hastened
by exhaustion of soil moisture and plant-food.

CHAPTER XXII

CONTROL OF SOIL MOISTURE

Value of Water in the Soil.--The amount of water in the soil each day
of the growing season determines in large measure the possibility of
securing a profitable crop from land. Observant farmers have noticed
oftentimes that the differences in yields on the farms of a region are
less in a wholly favorable season than in one of deficient rainfall.
The skill of the farmer in conserving the moisture supply in a wet
season is less well repaid because it is less needed. The poverty of a
worn soil is less marked in a favorable season. The land is accounted
poor because the supply of plant-food is inadequate for a drouthy year
in which a considerable percentage of the time produces little growth,
but most agricultural land has enough plant-food for a fairly good crop
when water is present all the time to carry daily supplies into the
roots. It is the amount of moisture in the soil that is the limiting
factor in the case of most land that is not in a high state of
productiveness.

The Soil a Reservoir.--The rains of the summer rarely are adequate to
the needs of growing plants. Some water runs off the surface, some
passes down through crevices beyond the effect of capillary attraction,
and much quickly evaporates. The part that becomes available is only a
supplement to the store of water made by the rains of the fall, winter,
and early spring.

If the soil were viewed as a medium for the holding of water to meet
the daily needs of plants, and were given rational treatment on this
basis, a long step toward higher productiveness would have been taken.
As has been stated, rotted organic matter gives a soil more capacity
for holding water. It is an absorbent in itself, and it puts clays and
sands into better physical condition for the storage of moisture. An
unproductive soil may need organic matter for this one reason alone
more than it may need actual plant-food.

Fall-plowing for a spring crop enables land to withstand summer's
drouth if it gains in physical condition by full exposure to the
winter's frost. It is in condition to take up more water from spring
rains than would be the case if it lay compact, and it does not lose
water by th