the subsoil is far down and covered
with a deep covering of vegetable mold. What are termed slough soils in
the Western prairies, therefore, are not well fitted for the growth of
alfalfa. On these it may not succeed well, when it may grow with much
vigor on the adjoining upland. When some wet soils are drained, alfalfa
may not succeed well on them for a time and later may grow luxuriantly.
This may arise from the lack of time for proper aeration after being
drained, or from the want of lime to further correct acidity in the
soil, or from the want of the proper bacteria. Notwithstanding that
alfalfa will not grow well on undrained lands that are naturally wet,
and notwithstanding that it will perish if the roots reach standing
water at a distance too near the surface, the best crops by far are
usually grown on irrigated lands. This arises, first, from the ability
to adjust the supplies of water to meet the needs of the plants, and
second, from the congenial character of the soil and subsoil. Next to
these the best crops are grown where congenial soils are underlaid with
ground water, not too near nor too distant from the surface. On these
soils the plants are largely supplied with moisture from the water below
ascending on the principle of capillary attraction. How near or how
distant such water should be will depend somewhat on subsoil conditions.
It would seem correct to say that it ought never to come nearer to the
surface than 3 feet, nor should it be more than 20 feet down. The most
suitable distance would be, say, 8 to 16 feet. When the roots of alfalfa
reach water at too short a depth they will die.

Alfalfa may sometimes be grown satisfactorily on soils subject to
overflow, but usually there is hazard in growing it on these. If the
overflow occurs comparatively early in the season, if it is not of great
depth, if it is of short duration, and if the waters quickly drain out
of the subsoil possessed by the alfalfa, it may receive little or no
harm from such overflow. Instances are on record wherein ice has formed
on alfalfa and yet the plants survived, but such a condition will
usually prove fatal to them. But should the overflow take place in hot
weather, usually it will injure the plants seriously, and may, indeed,
completely destroy them. So great is such hazard, that care must be
taken against the application of an excess of irrigating waters under
such conditions. Overflow waters that are stagnant are more inju