Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1909-02-08
! HOME COURSE IN
MODERN AGRICULTURE
.Ho,u Plants Eat and Gro,U
BY c. v. GREGORY,
Agricultural Division, Iowa State College
Copyright 1905 by American Press Association

to do well. This is because 1t cannot
get as much Of the mineral elements
as it needs.
Too much nitrogen in proportion to
the amount of mineral elements causes
the plant to ego all to vines" There
will be an excessive growth OF leaves,
but the yield of grain will be small.
Take an car of corn or bunch OF nay
and burn 1t. The ashes that are left
arc the mineral parts Of the plant.
These cannot be obtained frem air or
water, but must come from the soil.
Some of the most important Of thess
are iron, which is the substance that
helps 10 build up chlorophyll, and sui
phur, which is found in the nitroge-
nous parts Of the plant. There are a
number of others also, all of which
arc present in the soil in such large
amounts that there will probably al
ways be all that the crops can use.
Two of these minerals, however. po-
tassium and phosphorus, are not so
plentiful. When the plant cannot get
enough potassium the grain will not
be filled out we'll If there is too little
phosphorus, especially in the case OF
fruit trees, the development Of fruit
is checked. Adding barnyard manure
to the soil helps TO keep up the supply
Of these two materials. On farms
where little stock is kept or where
grain has been raised continually for
years and little attention paid to the
soil 1t is sometimes necessary to apply
phosphorus and potassium In the form
Of commercial fertilizers.
In the eastern part Of this country
there are many farms that have be-
come so badly run down that crops
will not grow at all unless they are
fed with commercial fertilizers. These
are very expensive, and it often takes
nearly all farmer makes to pay his
fertilizer bills. These farms would
never have become SO worn out II they
had been properly cared for. Leaving
plowed ground, especially on hillsides,
exposed for several months during the
fall and winter allows much plant food
to wash away Growing the same
crop year after year wears out the
land rapidly. Different crops require
different kinds of food. By changing
crops from year to year no one food
material is used to excess and the
others wasted BY keeping as much
stock on the farm as possible, saving
the manure carefully and spreading 1t
on the fields before it rots or teaches
away and by using leguminons plants
to gather nitrogen the soil can be kept
well supplied with plant food.
1t is much more profitable to feed
the crops in this way than to buy
plant food On the market at excessive
prices. Usually, however, the plant is
hungry for the mineral elements not
because they are not in the soil. but
because they are In form in which
1t cannot get at them. The roots Of
the plant spread all through the soil
in search of food. II you will look at
a little root through a nagnifying
glass you will. see that it is covered
with root hairs. II is through these
root hairs that the plant takes up food
from the soil. There are no openings
directly into them, but the walls are
so thin that the water can soak
through to the inside. Solid sub
stances, Of course, cannot get in, so
that the plant food must be dissolved
in water before 1t can get into the
roots and so up to the chlorophyll,
which is waiting to build it into seeds
or leaves.
If the soil has been worked until it
is fine and loose each little particle