Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1915-10-19
Reasons for Crop Rotation.

Farmers understand the necessity OF
rotating crops if they would get the bes,
results from their operations, but few
know just why they do it. 1t is often
said that different crops require differ
ent elements TO induce their growth, but
this is somewhat misleading, for almost
all crops use the same elements. 1t may
be said, therefore, that the reason for ro-
tation, so far as fertility is concerned, is
rather to supply some particular ele-
| ment in large quantities. This element
is usually nitrogen and the leguminous
crop is almost always part of the rota-
ton, in fact, to supply nitrogen seems TO
be the main purpose sought. Potash
and phosphorus are commonly put on
the land in the form of pure elements,
commercial fertilizers, or manure from
| the stables.
II is commonly considered that the leg
umes do not make demands on the
plant food in the soil. Were this strict
" true, crops of clover year after year
would constantly improve the condition
of the land. IL is not true, however.
Legumes add greatly to the nitrogen
content but detract from the store of 9th
er important elements. 1t is plain,
therefore, that they may not be grown
every year. Where three or four year
rotation is practiced, the nitrogen gath
ering crop plays an important part, as
this element is the least abundant in the
msnures usually applied in the farming
operations.
In the usual rotations, such as corn,
oats and clover, on the dairy farm, the
first two are large users of nitrogen
while the third gathers it and makes it
available. Other elements are returned
10 the soil with the stable and barnyard
manures. To get the full value of the
rotation, at least part of the leguminous
crop should be plowed into the soil.
Thus the first cutting may properly be
made aud cured for hay. Instead OF pas
turing down the later crop, or cutting IL
for seed, as is the common practice, il
should be returned to the soil, otherwise
the balance will not be maintained. The
rotation should be planned so that two
years out of three the crop will bring in
money. The third crop should be soil
builder. OF course il the legume is fed
TO the stock part of its value goes back
to the soil.
In the rotation mentioned, one crop
1ats-is a shallow feeder, that is. the
roots gather food only from near the
surface. 1t is evident that continual
cropping with oats, or wheat which
feeds in the same manner, soon depietes
the surface soil. Corn is also surface
feeder but it has some roots that extend
deeper, hence part of its food is drawn
from the stores farther down. Clover |
draws the most Of its food from still |
farther down-six or eight feet-and its |
nitrogen supply from the air. 1t also |
brings up much phosphorus and p, tash
from the subsoils, but il is for the nitro |
gen it leaves for the other crops that it
is principally valuable.
Rotating the crops helps to some ex-
tent in the control of diseases and insect |
pests. Many diseases, peculiar to GER
tain plants, remain in the soil year after |
year where the same crop is grown con-
tiuually. The same is true of insects.
Changing the crop starves both diseases
and insects. Insects migrate only to
limited extent and diseases almost not at
all. 1t is plain, therefore, that crop ro-
tation has a value in this direction. An
other reason for rotation is to control
weeds. Where grain crop is grown for
several years 10 succession, many weeds
are introduced with the seed and are
liable 10 become naturalized. Changing
the crop is about the only effective
means for getting rid of them.
All crops should be rotated and it re-
mains with the individual farmer to de-
eide what ones are best suited to his
condition and needs. There is really |
but one fundamental requirement in ro-
,ations-grow legume every third or
fourth year and return at least part OF
the crop to the soil.-C. II. Chesley, in
Hoard's Dairyman.