The progressive farmer. [volume] (Winston, N.C.) 1886-1904, 1897-09-21
WEEKLY DIGEST
Of Experiment Station Bulletins.

The effect of crop rotation and also
OF farm manures on the humus content
and fertility of soils has been under in
vestigation by the Minnesota Station
since the spring of 1892, and bulletin So
gives an account of the experiments
and the results reached.
The field chosen had been growing
small grain for forty years without fer
tiliztng, and though somewhat ex,
hausted, was in fair condition as to fer
tility. It was divided into six pl1ts,
and all were sown in wheat the first
year to see if they we're of equal and
uniform fertility. None differed in
yield more than bushel per ecre.
The plan of the experiment was to
grow wheat continuously on one plot,
oats on another, barley on third, corn
on fourth and all these crops in rota
ton with clover on the fifth, and in ro-
| tation with clover with clover and ma
nure on the sixth. Each crop was
weighed and analyz yzed, and the soil OF
each plot was analy z3d before n6ssafter
the experiment to determine the gain
or less Of fertility. The land was we'll
drained ard in good mechanical condi
tion, and the plots were separated by
strips six feet wide
The rotation on one plot was fret
year wheat and clover, second year
clover, third year wheat, fourth year
oats, fifth year corn and manure. The
other rotation was first year oats and
clover, second year clover, third year
barley, fourth year corn and manure.
It was found taat the clover seeded
with wheat did much better than that
soWn with oats, yielding over a thou
sand pounds more hay per acre the
second year. This is probably due to
the fact that oats are deeper rooted and
| grOsser feeders than wheat, and hence
they deprive the young clover Of more
Of the soil food than wheat does. 1t is
well known that oats will find soil food
enough to make q good crop on soil too
poor to produce wheat.
In 1895 the plot that had been in
wheat continuously yielded II bushels
per acre and the soil showed a iOss of
III pounds Of nitrogen per acre, only
25 of which was found in the crop
removed, hence the other 146 pounds
must have been leached out by rain
and evaporated into the air. On the
other hand, in the same year Q895),
| the rotation plot, which had been in
clover the year before, yielded % bush
els Of wheat per acre, and the soil
| showed a gain Of 81 pounds per acre
each year OF the rotation, notwithstand
| ing more had been removed by the
crops, because they were larger than
that this gain is due to two facts
namely: FIRST, the clover gathered and
stored in its roots and stubble 4arge
amount Of free nitrogen from the air;
| second, the humus added to the soil by
| the decaying roots and stubble Of the
clover beld the soil moisture in which
much nitrogen was dissolved, as q
| sponge holds water, thus preventing
much loss by teaching and evaporation.
These results show that in coutinu
GUS wheat growing the soil becomes go
barren OF humus that it loses by leach
ing and evaporation five pounds of
Nitrogen for every pound used by the
crop. Oats and barley show about the
same rate of loss.
In 1896 the rotation plot produced
but one fourth of bushel more oats
per acre than the plot that had been in
oats continuously, because of the above
noted ability of oats to get good liv
ing on poor soil; but the all oats plot
lost 1876 pounds of nitrogen per acre,
while tae rotation plot still showed a
net gain of nitrogen.
In 1896 the plot which had been in
corn continuously yielded 441 bushels
per acre, and the rotation plot, with
manure, yielded 66f bushels per acre
q gain of % bushels per acre, and at the
same time the all corn plot showed q
yearly loss Of 64 pounds Of nitrogen per
acre; while the rotation plot showed q
substantial net gain Of this valuable
fertiliziug element. o: the 81 pounds
lost annually on the all corn plot, 55
pounds were stored in the crop and 90
lost By teaching and evaporation. Thus
it is seen that while wheat, oats and
barley lands lose about Ave pounds of
nitrogen for every pound used By the
crop, corn loses but little more than
half q pound of nitrogen for each pound
used by the crop. This is thought to
be due to the fact that the corn crop