and it may be hastened by tillage.

Srobebly no agricultural fact is more cenemli
known by fexrmers and land-owners, than thet Terie aitter
in productive power. Even though plowed alike and at
the same time, prepered the same way, planted the same
day with the same kind of seed and cultivated alike,
nevertheless the best acre may produce twice as large a
crep as the poorest acre on the same farm, if not indeed,
in the same field; and the fact should be enphasized that
with the normel rainfall of the district the productive
power of the land depends primarily upon the stock of
plant food contained in the soil and upon the rate at
which it is liberated just as the suecess of the merchant
depentis primerily upen his stock of goods ané the rapidity
of saies. In both cases the stock of any commodity must
be increased or renewed vhenever the supply of such
commodity becomes so depleted as to Limit the suecess of
the business, whether on the farm or in the store.

AS the opganic matter decays, certain Cecomposition
products are formeé., including much carbonic acid, some |
nitrous acid ané various organic acids and these hare the i
power to act upon the soil and disselve the essentisl
minerel plant foods, thus furnishing soluble phosphates,
nitrates ané other selts of potassium, magnesium, etc. for
the use of the growing crop.

Fresh ergenic matter decomposes much more rap id-
iy than old humus, which represents the organic residues
most resistant to decay and which consecuently has
accumulated in the soils during the past centuries. The
decay of the old humus can be hastened by tillase, which
maintains a perous condition and tims permits the oxygen
of the air to enter the soil more freely and to effect
the more rapid oxidation of the organic matter, and elso
by incorgorating vith the old, resistant residues some
fresh organic matter, such as farm manure, clover roots,
etce, which decay rapidly and tms furnish, or liberate,
organic and inorsenie food for bacteria, the bacteria,
under favourable conditions, appearing to have power to
attack and decompose the old huems. It is probably for 4
this reason that peat, a very inactive and inefficient
fertilizer when used by itself, becomes much more effec-
i7yve when compesited with fresh farm manure; so that two
tons of the composit may be worth as much as tee tons of
the manure. Sacterial action is also promoted by the
presence of limestone.

The condition of the organic matter of the soil
is indicated more or less definitely by the ratio of
cerbon to nitrogen. gS an average, the fresh organic if
matter incorporated with soils contains about twenty
timea as much carbon es nitrogen, but the carbonhydrates
ferment and decompose mich more rapidly than the nitrogen-
ous metier; and the old resistant organic residees such
as are found in normal subsolis, commoniy contain only
five or six times as much garbon as nitrogen. Soils of
normal physicel ondition, such as Loam, clay leam, and
fine sandy loam, when in gooé productive condition, con-
tain sbout twelve to fourteen times as much carbon as
nitrogen in the surface soil; while in old, worn soils
that are greatly in need of fresh, active, organic manures,
the ratio is narrower, sometimes falling below ten to
one of nitrogen, Soils of cut-over or burnt-over