Nutrient Management - Growing Organic Orchard Fruits - page 406

value in orchards is its ability to raise the soil pH. Dolomitic limestone, or
dolomite, is a magnesium-containing form of limestone.
LEATHER MEAL
Leather meal is a by-product of the tanning industry. Although a relat-
ively rich source of nitrogen (10 percent), it is often contaminated with
chromium and cannot be used in organic orchards.
Micronutrients. Boron, copper, iron, manganese, molybdenum, and zinc are
occasionally deficient in orchards. While sulfates of these nutrients are avail-
able, your best results will probably come from applying foliar sprays of che-
lated products (see page 107 ➔ ) , described above. Apply them only when
there is a documented deficiency of the nutrient in the soil or tissues.
Mushroom compost. Mushroom compost is usually comprised mostly of
sawdust, rice hulls, straw, or similar woody organic materials that have been
used to grow mushrooms for human consumption or medicinal purposes. It
typically contains less than 1 percent each of nitrogen, phosphorus, and po-
tassium and is most valuable as a source of organic material for mulching.
Test the material for pesticides and document that it is pesticide-free before
applying it to your soil.
Peat moss. Peat moss is extremely valuable for containerized plant produc-
tion, but it is normally prohibitively expensive for all but a small home orch-
ard. Its value as an amendment is to increase the soil's water-holding capa-
city and is most useful on sandy soils. It is also acidic and somewhat useful
in temporarily lowering soil pH. Ensure that any peat moss you use has not
been amended with synthetic fertilizers or wetting agents (surfactants).