Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, May 22, 1994 TAG: 9405240014
SECTION: HOMES PAGE: B-2 EDITION: METRO
SOURCE: John Arborgast
DATELINE: LENGTH: Medium
E. D., Fries
A: Is this letter two questions with something left out: one about marble chips and the other question about a controlled release fertilizer?
Since marble is limestone in a more or less crystalline state, using marble chips as a mulch would be just like putting lime on top of the soil, thus causing the pH of the covered soil to increase. Yes, marble chips would harm the soil for azaleas by causing the pH of that soil to increase above the acidic level that this acid loving plant needs. The rise in pH resulting from marble chip mulch may be very gradual. The white dust on marble chips is pulverized rock.
I can't find any information on the specific controlled release nitrogen fertilizer called Polyon. Of course, the company that makes this fertilizer as well as any local or regional businesses that sell it should have all details. Generally controlled release synthetic fertilizers have some kind of coating around the actual fertilizer granule. As the coating deteriorates, the nutrients are gradually released to the soil. There are at least two types of coatings and thus two different ways for the coating to break down: the type affected by moisture, and the kind affected by soil microorganisms, which are controlled to a certain extent by soil temperature. The coating also determines over how long of a period of time the nutrients will be released. In addition to this, some fertilizer products will use different sized particles to cause a difference in the release of nutrients.
READER'S RESPONSE TO D.J. OF MAY 8:
Beneficial nematodes are available from: Gardeners Supply Company, 128 Intervale Road, Burlington VT 05401; telephone 1-802-863-1700; they offer one million nematodes, which would treat 2,000 square feet, for $18.95.
John K. Arbogast is the agricultural extension agent for Roanoke.
by CNB