A Few Combinations Are Safest
It is the best judgment of scientists
to-day that greater results would be obtained from the use of
commercial fertilizers if the number of formulas could be reduced to
ten, or even a less number. The satisfactory fertilizers fall into
1. The phosphatic fertilizer, carrying phosphoric acid to land that
gets its nitrogen from clover or stable manure, and that continues
to supply its own potash. Such a fertilizer should have a high
content of phosphoric acid in order that the freight charge, per
pound of plant-food, may be as low as possible. Acid phosphate,
basic slag, and bone are chief in this group.
2. The combination of phosphoric acid and potash that is needed by
soils obtaining all required nitrogen from clover or manure. In
most instances the phosphoric acid should run higher than the
potash, but the percentage of potash should never run lower than 4.
A lower percentage of potash is not as profitable as a higher one,
provided any potash is needed. The potash content should be greater
than that of the phosphoric acid in case of some sandy soils and of
some crops of heavy leaf growth, including various garden crops.
3. The so-called "complete" fertilizer that supplies some nitrogen
with the two other plant-constituents. Such fertilizer should
furnish, with few exceptions, 3 per cent of nitrogen, if no more.
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