The Lynden tribune. [volume] (Lynden, Wash.) 1908-current, 1914-01-29

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poor quality Of barnyard manure
which has had much Of the plant food
leached out Of it has q considerable
value because of the humus it makes.
Another cheap and valuable source
of humus, but one which must be used
Understandings, is crops grown to
turn under as manure. The legumes
are especially valuable for this pur-
pose because Of the nitrogen they con-
tain, but other crops. such as rye and
even corn sown thick, may sometimes
be made TO supply large quantities or
humus Of fair quality. Crops thus
used are called green manures.
A proper circulation Of air in the soil
is just as important as any other fac
tor of plant growth. Nearly half OF the
volume of ordinary soils is occupied
by air spaces. Plant roots must be
supplied with air, and the soil must be
porous enough TO permit Of free circu-
lation. A good supply Of humus and
proper tillage will accomplish this re-
suit in clay soils. Sandy soils are usu-
ally too porous, needing humus TO help
them retain water.
Another reason why air must circu-
late freely in the soil is that large
quantities of oxygen are required to In
sure proper decay of organic matter to
supply plant food Also carbonic acid
gas is produced by the decay OF Or
ganic matter, and this must escape cas-
lily to make room for the atmospheric
oxygen needed in the soil. One OF the
most important objects Of blowing Is
to loosen up the soil for aeration.
Considerable evidence has been &C.
cuInulated during recent years to show
that during the growth Of the plant
certain unknown organic substances
are given off which, when they accu-
muate in the soil TO any extent. are
harmful to the further growth OF plants
of the kind that produced them. 1t is
possible that some of the benefits
known to arise from systematic crop
rotation may be explained on this ba-
sis. These harmful substances seem
to be disposed of rapidly by certain
soils. usually those in which organic
matter is readily converted into humus.
In connection with the study OF these
poisonous organic products it has been
found that they may be destroyed or
at least rendered harmless in variety
of ways. Barnyard manure or decay
ing organic matter, such as green
crop of rye or cowpeas. turned under
has a very marked effect in freeing the
soil fpnrn fharn 4 lrnnSf all nf tho com
mon commercial fertiliZing materials
act more or less in the same way.
Thorough and complete airing OF the
soil by blowing and thorough surface
tillase will often destroy or overcome
these poisonous substances. When the
same crop is not grown oftener than
every three or four years on the same
hand the injurious substances a crop
throws off seem to have time TO disap-
pear before the same crop Is grown
again: hence the benefit from crop TO-
tation When the soil is well supplied
with humus there is seldom any trou-
bic from this source, and the same crop
may be grown year after year with
good yields. though continuous cult
vation Of the same crop may invite In
jury from certain insects and fungous
diseases which live over in the soil or
in the remains of the crop.
Improper methods Of tillage add very
greatly to the evil effects that result
from lack of humus. In many parts
of the country the land is plowed only
three or four inches deep. In most
cases work done in subsoiling is prac-
tically wasted, and it is doubtful If 1t
ever pays A much better method is
to pillow a little deeper each year until
a depth of eight or ten inches is reach
ed. This gives a deep layer Of good
soil. particularly if the supply Of humus
is kept up.
When new soil or that which has
lain undisturbed for several years Is
broken up it is always best to pillow
deep from the beginning. for the deep
er layers will be about as fertile as
any. except the top inch or two. 1t is
wise. too, never to pillow the same
depth twice in succession. In general.
fall blowing should be from seven to
nine or ten inches and spring blowing
from five to seven inches deep. There
are special cases in which these rules
do not apply.
We plow the soil in order to loosen
up its texture and get air into it; also
to turn under stubble, manure. ETC.. to
make humus. Killing weeds is another
object accomplished by blowing. After
a soil has been thoroughly pulverized
to great depths. SO that there is no dan
ger of turning up packed clay. the
deeper the blowing the better the crops.
But the cost also increases with depth,
so that ordinarily 1t does not pay to
plow more than about ten inches deep.
Some crops prefer rather loose seed
bed Other crops. such as wheat and
alfalfa. prefer a fairly compact seed
bed; hence frequent narrowing and
rolling after blowing is good practice
before seeding to these crops. Never
theless it pays to pillow the land for
them. even if we have to compact 1t
again before seeding.
Sandy soils are usually not injured
by handling when wet, but the case is