The La Jara chronicle., 1910-05-27
AGRICULTURAL DEPARTMENT
Directed by Colorado Agricultural College
CROP ROTATION.

According to their method OF
growth and general effect upon the
soil. field crops may be divided into
three classes: perennial grasses and
lesunes. cultivated crops and small
grains and uncultivated annual for.
age crops. The best results are OBJ
tanned by alternating these three
classes OF crops with more or less
regularity, in place of raising one
kind continuously.
Perennial grasses and legumes. as
class. are soil protectors. soil re-
newers. and soil builders. They leave
a considerable amount of vegetable
matter in the soil, which by decay,
furnishes good supplies of plant food
for crops which follow. Through
several years growth these crops de-
velop rather deep, penetrating root
systems. which gather certain min
eral foods in the lower layers of the
soil and leave them in the upper
layers when they decay. These de-
cayinS roots also improve the physi-
cal condition of the soil by opening
dt up and increasing its capacity to
absorb and retain moisture. As is
well known, alfalfa, the clovers, and
other legumes not only possess the
good characteristics of the grasses
but, in addition, have the ability
(through symbolic bacteria) of ac-
tually adding nitrogen to the soil
from the air. One of these legumes
should by all means be included in
every rotation.
Cultivated crops. through the till
age and cultivation they receive
conserve the moisture. This results
in conditions favorable for the de-
velopment of bacteria which hastens
the decomposition and chemical
changes which make plant food avail
able. These crops tend to deplete
the fertility rather rapidly and to re-
duce the organic matter. Well cu'-
tivated crops do not remove SO much
soil moisture as the crops in the
ether classes
Small grains and uncultivated an
nual forage crops draw heavily upon
soil fertility and sell moisture. They
reduce the organic matter rapidly,
especially If the straw is all removed.
Many soils. after a few years crop
ping with grains, become finer in
texture, more compact and heavier
to handle. They dry out quicker
than they used to. and often turn
over in Jumps and hard clods when
plowed. The good tilth of virgin
grass lands is more or less COM
pletely restored to worn out soils
when they have been put into
legume or a grass for a sufficient
.ength of time.
AS a general rule, cultivated crops
like corn and potatoes. should fol-
ability to get their food under more
adverse circumstances than some of
the grains like barley and wheat.
and the constant stirring helps
greatly to subdue the sod and leave
supply of easily available plant
IOOd 1or the crops that follow.
The grain crops should ccme in be-
tween the cultivated crops and the
grass crops. The cultivated crops
have destroyed many weeds which
might injure the grains, and they
have prepared plant food and left
the soil in good physical condition
By the time several grain crops have
been raised the soil is again low in
available fertility and organic mat
ter, and is rather hard and compact
The grass crops will largely correct
these conditions. If nurse crops are
used in seeding the land. the grain
crop comes in the proper place to
be used for this purpose.