Read some studies where leaching from fresh needles in large quantities
does cause the pH to be lowered, although soil buffering in some areas
made the changes temporary at best. Pine needles (along with other
acidic items) are recommended as mulch for acid loving plants by most
experts to take advantage of the leaching process. This makes continual
applications of acidic material a must for some plants. Pines for the
most part do prefer acid soils, but many oaks thrive in alkaline soils.
Both trees in a natural state, would affect the pH due to leave drop to
some extent within their own drip line and these changes would most
affect the feeder roots which tend to be close to the surface.
As far as composting is concerned, during the decomposition process,
the pH will be on the acidic side. But your observations are correct,
as once the compost completes its cycle, the finished product regardless
of the initial ingredients will be neutral or nearly so.
susan
Dan Sterner wrote: > > On 27 Apr 1999 18:23:13 -0400, ntbandit@globec.com.au wrote: > > >the pine needles should be making the soil acidic so an application of > >dolomite lime at the prescribed rate will be needed to adjust this, soil ph > >test kits can be bought from better landscape centers to test the soil > >acidity. > > Someone else posted this same idea the other day, and I'm not sure that's > true. A chicken and egg type of question I guess, does pine and oak make > soil acidic, or do they just like to grow in acidic soil? > > I use pine needles and oak leaves almost exclusively as mulch, have done > so for years, and have noticed no change in the ph of the soil. As they > decompose, in the upper inch or so of soil, maybe. Once decomposed, I > doubt it, based on my own experience with it. My (cold) compost pile has a > lot in it as well, and though the ph of the soil started at about 7 > several years ago it still sits right at 7.1 according to the soil test > this spring. My thought is that a soil tends to return to its natural > state, so any lime or acidic matter added would have a short term effect > at best, and unless it's dug in before decomposed, only on surface roots. > > There was an article I read some time back written by a gentleman who > wanted to put this idea to the test. He collected christmas trees and > chipped them, built his whole garden based on decomposed pine. Claims to > have a wonderful garden with no ph problems. That agrees with my > experience.