Agriculture Reference
In-Depth Information
is a hydrated form of magnesium sulfate and used in the production of Ep-
som salts.
Feather meal.
This is a by-product of poultry slaughterhouses and contains
7 to 12 percent nitrogen, depending on how it is processed. The nitrogen is
released slowly over 4 months or more. Nitrogen from feather meal generally
costs about 10 to 15 percent more than that from the more rapidly available
nitrogen in blood meal. If you can obtain feather meal inexpensively, it can
be an effective slow-release fertilizer. Be sure to obtain a product that is free
from pesticides.
Fishemulsions.
Emulsions contain only about half of the nitrogen, phosphor-
us, and potassium found in fish meal, but the nutrients are available much
more rapidly. According to the U.S. National Organic Program, forms that
are fortified with urea or other synthetic plant nutrients are prohibited. Phos-
phoric acid can be used as a stabilizer, but the resulting product may not
exceed 1 percent, by weight, of P 0
3
2
While some people recommend applying fish emulsion to the foliage in
order to correct nitrogen deficiencies, the practice is not effective. Nitrogen
and the other macronutrients generally cannot be taken up through the fo-
liage in large enough quantities to significantly improve a plant's nutritional
status. Studies have shown that, in cases where foliar feeding increased the
macronutrient concentrations in orchard trees, the fertilizer solution drip-
ping from the leaves onto the soil provided the benefits. For nitrogen, phos-
phorus, and potassium deficiencies, apply fish emulsions to the soil. Fish
emulsion can be applied as a foliar spray, however, to supply micronutrients;
these can be taken up in significant quantities through the leaves.
Fish meal.
Fish meal is a rich source of nitrogen (8 to 9 percent) and also
provides phosphorus and potassium. Depending on the preparation, fish meal
can also provide micronutrients. Nitrogen from fish meal is available rather
