The Relation 0f Sulfur to Soil·Fertility. 621
The highest yields over the checks, using the sulfate,
Q were obtained with magnesium, ferric, sodium, potassium
and ammonium sulfates in the order given, although several
large gains were obtained with others. With the carbonates
and oxides, the best in order were sodium and magnesium
carbonates, ferric and ferrous oxides and ammonium car-
bonate. ·
Of the substances used, only chromic sulfate, calcium
carbonate, ferrous sulfate and cobaltous carbonate, in the
order given, showed losses. Ferrous sulfide, nickelous sul-
fate, cupric sulfate and carbonate, manganous carbonate and
i lithium carbonate gave about the same results as the checks,
while the remainder gave substantial gains.
With the variable amounts of sulfur used, all gave sub-
stantial gains, the best result being obtained with 100 pounds
per acre, and any amounts above this gave gradual decreases '
as the amounts applied became larger. That the sulfur in
y all cases had been partly oxidized to sulfate when utilized
by the plants, will be shown later.
s The poor results obtained with calcium carbonate indicate
that the nutritive materials in the sand may not have been
properly balanced for the best growth of alfalfa, and already
contained an abundance of this material in view of the fact
. that a further addition caused a loss. This might have been
caused by the ratio between the amounts of calcium and
magnesium becoming too large since the experiments with
magnesium carbonate or sulfate gave large gains. This is
an interesting point and assumes considerable importance
when applied to soil conditions.
In this connection, the work of McCool‘“ is of interest
since he has shown that a close relationship exists between
the nutrient and non-nutrient basts on the growth of plants
and an oversupply of one element may prove harmful but its
effect can be counteracted by the presence of others. ln
’ other words, all elements which are generally present in
combination should be properly balanced for the best growth
of a plant largely for the same reason that a balanced ration
has been found best for an animal.