Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1907-05-02

Inc most thorough investigator ana |
student of actual soil conditions in Hi !
nois and the highest authority on this |
subject, is Professor Cyril G.. Hopkins |
of our experiment station. In his adj |
dress at the Illinois Farmers institute, |
he spoke substantially as follows con
corning rotation of crops:
The only kind of soil treatment in
common use that is even believed to
benefit the soil is Il crop rotation i'll
Guiding an occasional clover crop, but
that rotation is a means of deplering
the fertility, and the clover used in
this way in grain farming serves only
as Il most powerful soil stimulant leav-
ing the soil poorer with each passing
rotation until crop yields become re-
duced, clover being the first crop to
fail in this system. At this point land
values usually begin to decrease. I'm
der the successful clover system of
grain farming the land owner may re-
Ceive One-half of a GO buShel crop of
corn, which at soc a bushel will return
$1,000 per acre-50 cents for taxes and
) per cent interest on 5000 land, but 10
or 20 years after the clover system
fails the land owner may be receiving
| only one-third of 50 bushels of corn per
acre, which with the same price and
tax would leave him only So per
cent interest on $50 land.
Where Rotation Is Sufficient.
Crop rotation alone is sufficient to
| maintain the fertility of some soils at
Ia low yielding power, as on sloping
| land whose surface soil is washed
away at least as rapidly as the fertili-
y is removed by crops and whose sub
soil is as rich or richer than the sur
face. Such lands are valued at $40 to
500 per acre.
/ Il cannot comprehend how it is pos
Sible to maintain the common Illinois
prairie and level upland at their pres
ent value and productive power if we
continue to remove from these lands
larger amounts of phosphorus and nj
| rOgen than are returned.
| Effect of FOur-Year Rotation.
| Suppose we are practicing a four
year rotation: Corn two years, GA s
with clover seeding the third year, the
| lover for hay and seed crops the
| fourth year. Let us assume yields of
| 100 bushels of corn per acre, 100 bush
| lis of oats, and four tons per acre of
| lover tsuCh yields have been prOduc-
| Id. The four crops in such a rota-
ion would remove 81 pounds of phos-
| Dhorus per acre from the soil, or if
| We leave the stalks on the land, 60
pounds of phosphorus. The principal
ype of soil in the Illinois corn belt av-
RACES about 1900 pounds of phos-
)horus in the first seven inches, and
his entire amount of phosphorus would
re sufficient for only 40 years of such
'arming. On the other hand, suppose
With this crop rotation we can secure
rom the soil each year only 1 per cent
If the phosphorus contained in the
irst seven inches; this would be only
2 pounds year, and would necessar
ly reduce the crop yields much below
he amount suggested.
failure Unless Phosphorus is Returned
"On the ordinary soils of Illinois, ulti
mate failure is the only future for thi:
system of farming, even if we consider
the phosphorus alone. But this deple
ton of phosphorus may be made up by
returning that element to the land in
bone meal, in rock phosphate, or in
sufficient amounts of farm manure.
Neither Can Nitrogen he Maintained.
| Three crops of corn in this rotato'
would remove 300 pounds of nitrogen
lper acre. If all the nitrogen containet
in the clover crop is taken from thu
air, the clover roots and stubble wouiC
Happily only so pounds of nitrogen to tn,
soil. Here will be a net loss of NOR,
than 200 pounds of nitrogen in this 70
ltation. 1t is not possible to maintain
the supply of nitrogen by such as sys
tenn. Where this rotation is succe IS
full for time, it is due to the fact that
the soil nitrogen has been drawn upol
tyear by year, while the chief effect o
the clover has been to extract phos
IphOrus from the soil for its owl
tgrowth and for the use of succeedin.
/ Icrops.
| eff the yields were only half thos
/ assumed above, they would not be &c
/ duced so rapidly. but it would only D
"a matter of little longer time whe,
lsuch rotation would faiD.''
RI Where the Glover Nitrogen Goes.
III On land capable of furnishing nj
|rogen for even 50-bushel crop G
| lcorn, the clover crop will undoubtedl
/ draw third of its nitrogen from tn
soil and not more than two-thirds fror