I've seen fish emulsion products that have
had chemicals added to make a more balanced
N-P-K ratio, but it was generally noted on the label.
The thing with using raw, mined rock phosphate
is that it takes awhile for soil organisms to make
the phosphorus in it available to plants. If you
are thinking ahead, amending this year for the soil
you want next year and the year after, it is as
natural a source of long-lasting phosphorus as
any.
If your soil needs more phosphorus *right now*,
however, and enough to last the summer, rock
phosphate is not so handy. Triple phosphate is
cheaper than guano, etc, so that gets used a lot.
__________________
--
alias
|