Los Angeles herald., 1910-02-20
80
PLANT FOOD

tural Experiment Station).
Law of the minimum-Since so many
conditions surround and influence the
growth of plant it is important to
find out which ones affect the growth
of the plant most. 1t has been found
by experimentation that it is not the
most favorable conditions, but the
most unfavorable ones which have the
greatest influence upon the growth of
a plant. There may be one hundred
conditions favorable for plant growth,
and five or even one only, which Is
unfavorable. 1t is not the many favor
able conditions, but the few unfavora-
Bile ones which influence the growth of
the plant or crop.
If a field is unproductive on account
of poor drainage or because of a lack
of humus, it would not be made more
productive by adding commercial ferti-
lizer. On the other hand, If field is
unproductve, due to a lack of avail
able plant-food, then the addition of
fertilizers will increase its produc-
tivity.
The essential conditions of a field
which are the poorest or at the lowest
ebb must be sought out and improved
before the fertility of the fields is in
creased.
1t happens many times that poor
yields are not due at all to a lack of
plant-toou, Dut are que TO eSSeHlidl
conditions other than those of plant
food.
Plant t-food-Authorities differ as to
the number of elements which are es-
sental to plant -growth-some give
nine or ten, others twelve and even
fourteen. At the very outside, of all
the elements known to exist. only
twelve or fourteen are necessary to
plant-growth.
The plant-food elements are as fol-
lows: Carbon. hydrogen. oxygen. nj
trogen, sulphur, phosphorus, chlorine,
potassium, calcium. iron, magnesium,
silicon. sodium and manganese.
Some authorities question the neces-
sity of manganese and sodium
Questioning the soil-The farmer
may question the chemist, or he may
question the soil. Analysis may show
approximately 1000 pounds nitrogen;
10,500 pounds phosphoric acid; 1880
pounds potash in the surface foot per
acre. Much of this plant-food may or
may not be available for a growing
crop.
If an old rusty safe, with doors
locked, fell into the hands of a farmer
and he knew that this safe contained
$4,000, it would be a great incentive
to try to unlock the safe and utilize
the money. So, also, if a farmer has
his soil analyzed and finds that it con-
tains 10000 to 10000 pounds of plant
food per acre, even if not available,
this fact should be worth much to the
farmer because it should give him
strong incentive to try to farm in such
a way as to gradually make available
for his crops this vast amount of
plant-food which is locked up in his
soil.
From Every Farm Experiment Sta
ton" by Prof Erwin e Ewel, first assist
ant. division of chemistry, L. S. departemnt
of agriculture, in department OF agriculture
Year Book for 1891
All food for men and animals is di-
rectly or indirectly the product of veg
etable life. Therefore, before the nu-
triton of animals and men can be
achieved to the best advantage, a
thorough acquaintance with the laws
governing the nutrition of plants is
necessary. For the successful produc-
ton of any plant an abundant sup
ply of every kind of food necessary
for its growth must be present in
readily available form in the soil or
in the air.
1t is Just as impossible to grow
plants in a soil containing only avail
able nitrogen and potash, or lime and
phosphorc acid or silica and iron, as
it is for a carpenter to build modern
frame house with only window glass
and nails, or with only boards and
mortar.
1t is Just as useless to expect
plant to thrive in a soil deficient in
potash, even though abundantly ma
nured with nitrogen and phosphoric
acid, as it is to expect the carpenter
to build the house with a million feet
of lumber and no nails. 1t is quite as