The Ottawa free trader., 1886-08-28

wards II VIII part with the water IL held
only in drops, and ultimately these will
cease, yet the cloth is wet-that Is, II holds
a perceptible amount of water which is
held by force stronger that gravity, and
| which can be removed only by evaporation
Now, II we examine the cloth in the frs,
stage we will find these spaces between its
tibres completely filled with water, but In
the second stage We will find the air ocCu,
pying these, and the remaining water held
to the fibers by adhesive attraction, which
can be entirely overcome only by eyapOra-
tion. In the first stage we still call il water
but when it is held 10y adhesion only is it
called moisture.
To apply this illustration we must bear
in mind that the soil is made of particles of
different materials and of varying degrees
of tineness. These PARTICLES capable Of
holding by adhesive attraction Il certain
amount OF water which gravity is not able
to displace. In this condition the inter
spaces between the particles are filled with
air; but if this quantity be exceeded, the
spaces become filled with water, thus eX-
cluding the air, and then we say the soil is
saturated, or contains soil water" before
it was only soil moisture. To the proper
understanding of this subject 1t is impor-
tsnt that we apprehend this distinction
clearly. The water adhering to each par
ticle of the soil is in the closest possible
contact with it and consequently In the best
condition to take up whatever soluble ele-
ments it my contain and thus 1t becomes
rich in the mineral and nitrOgenous ele-
ments of plant food. But if the soil be
saturated this interstitial, or soil water, will
hold in solution little or nothing that will
serve as plant food, and the water absorb
ed will be exhaled from the leaves, and the
plant will ultimately die of starvation. The
first indis cation of this condition is the sick
ly, yellow color of the leaves, indicating
the loss of chlorophyl. Now, this sub
stance which gives the dark green color to
the foliage of healthy plants is a compound
containing nitrogen which the roots must
absorb, in the form of ammonia or nitric
acid, in solution in water. But these are
absorbed in the vaporous state and held by
CarbonaceOus particles of the soil, or they
are slowly evolved from the decomposition
of the particles of animal or vegetable mat
ter in the soil and, of course are first taken
up by the moisture adhering to these parti-
cles. But the water of santuratiOn filling
the spaces between these PARTICLES will re-
Ceive too small a share of this essential nu-
trieut to meet the demands OF healthy plant
life. In acquatic plants, such as rice aud
other water grassess the great abundance
Of tibrous roots is special provision to
meet this condition.
But there is another direction in which
soil water acts iniuriously to growing crops.
In a soil in which the interspaces are filled
with water, the air is necessarily excluded.
Now, that the presence of air Is necessary
condition of the healthful performance of
root functions in ordinary crops, is an ad-
mitted truth among practical farmers,
whether we may understand the manner of
its actions or not. TO secure this is indeed
the chief end Of cultivation. The oxygen
of the air is the great promoter OF chemical
activity everywhere, and this agent, when
present, is constantly acting on the mineral
elements Of the soil, to bring them into a
soluble condition that they nlay administer
to plant growth 1t also acts on the organic
matter in the soil to breaE up its complex
structure and resolve il back into the sim
pier forms of plant food. The long contin
ued exclusion Of air by water, in soil rich
in vegetable matter results in the formation
of compounds entirely different from those
formed in free contact with air. Several
of these are acids and are poisonous 10 the
roots of ordinary crops Such soils are
known at once hy the growth of sour dock,
sorrel, smart-weed and other acid plants.
Farmers call these cold, sour lands" prob
ably without appreciating the propriety of
the name. Frequently these saturated soils
are made such by compact, impervious
subsoil of clay which, absorbing these
acids, retains them, and when the roots OF
corn and other deep roofing crops reach
this, they die outright Such soils some
times occur in our wet prairies and are
quite common in some parts of Texas,
wnere they are known as "Poison Soils"
But thorough drainage and dressing with
quiCKlime will not only cure them, but by
contact with the air the poison will be con
verted into a valuable fertilizer.
But chemical action is nearly always ac-
companied by change of temperature,
and when that action involves the cOmbina-
ton of oxygen with any other substance
there is always an increase Of temperature.
This is especially important in the spring
months and its effect is visible in the early
starting of vegetation on we'll drained land.
But here can be no chemical action with
out setting In motion electric currents.
What influence this may have on vegetable
activity we are not prepared in the present
state OF our knowledge to state definitely
but il is fair TO say that vegetable life can
not he indifferent to active electric currents.
II will thus be seen that prime consider
alton in Intelligent farming is 10 relieve
the soil of free water and 10y that term is
meant water filling the interspaces OF the
soil and free 10 escape by IT. own weight as
snon az a way to escape is opened 10 II; and
az the same time TO preserve As far as pos
-ibe a uniform state of soil moisture. II
Is hardly necessary 10 say with our present
knowledge Of this climate, the most direct
route 10 the accomplishment of both these
objects is by system Of we'll constructed
underdrains We say 3rcV constructed, for
many of the tile drains OF this State, espec
ially nf the early made ones, fall in the ac
conplishment of their OBJECT, IN part, at
least. These failures are chiefly from two
causes: % The insufficient depth of the
ditch, and q the lack of capacity In the
drain 10 carry off the soil water as rapidly