Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1880-12-17
Agricultural.


The following report Of series Of expert
m,lis 10y Lnw,s Il Gilbert of England has
b..u the rounds of the agricultural press;
Forty lrnrs ago Messrs Lawos & Gilbert
Of England b, gan series Of experiments in
wheat growing. They selected plats of
ground--in some they tried different manures,
while on one plat no manure or change of
crop was allowed but wheat followed wheat.
successfully, for forty years. In that time
there has been a decrease of Just ten bushels
per acre in the yield-one-fo bushel per
acre a year. Taking this as a standard case,
farmers who follow wheat with wheat not
giving the land any needed rest or feeding it
with manure, or green crops turned under
may look for a decrease, of course less some
years than others, but an average of one
fourth bushel per acre year.
The result of the experiment of continuous
cropping for forty years is valuable if taken
for no more than what it proves, which is sim
ply the result on the land which was used for
the experiment. To assume from this exper-
iment that an average decrease from year to
year Of only one-fourth of bushel per acre
may be expected with continuous cropping
without manure is absurd. The results of
such experiments would, of course, have a
wide variation according to the quality of the
land. Some soils would reach the limit of
their exhaustion, not only of their wheat pro-
ducing capacity, but of their power to pro-
duce any crop until their fertility was re-
stored, in less than fourth part of the time
that this experiment continued. Most of the
soil in the Eastern states, If cropped in this
way, would produce nothing worth gathering
in less than ten years much of it would be
exhausted in five years. On the other hand
it is claimed that there are soils in some of
the Western states and in the Mississippi val
ley that have been cropped for fifty success
sve years without the use of fertilizers, and
without having their fertility sensibly dmin-
ished Every variety of soil from complete
barrenness to the highest fertility is found.
1t is obvious that the diminution of the year
ly product. when successive crops are re-
moved from the land and nothing added to it,
depends upon the character of the soil. 1t is
altogether too exact conclusion to take the
experiment of Lawes q Gilbert as a standard
and say that the annual decrease Of Just one
fourth a bushel per acre, on an average, may
be looked for
1t has been held by some writer's that there
is limit below which no further exhaustion
of the soil takes place. Fields that have been
cropped with rye for many years, after being
reduced to the limit of six or eight bushels
per acre have continued to yield about this
average for an indefinite period. Prof Col
lier says if successive crops are removed from
the soil without any return of the mineral
matters which are necessarily carried off in
them. there generally, if not invariably,
comes time when a marked decrease in the
annual harvest is seen, which decrease con-
tinues until ii reaches a point at trhich 10
steddHy remains, with no further perceptible
change in either direction. The theory
which explains the limit of exhaustion is that
the natural changes going on in the soil are
sufficient to liberate annually from insoluble
compounds as much of the mineral consttu-
ents of the plant as the crop removes,