Re: coffee grounds as acidifiers
- To: M*@ucdavis.edu
- Subject: Re: coffee grounds as acidifiers
- From: R* F* D*
- Date: Fri, 25 Feb 2000 23:10:13 -0500 (EST)
At 10:25 AM 2/26/2000 +1300, you wrote:
>One of the most interesting findings of organic experiments is that once
>a soil is alive with all the appropriate organisms, irrespective of what
>it starts at, the pH will gradually even itself out, usually somewhere
>close below the neutral point in cropped beds, but probably somewhat
>lower in shrubberies. It seems that the organisms in such live soils can
>markedly influence the reaction of the substrate according to their own
>needs and the needs of the plants they associate with. In fact some
>organic thinkers now say that pH is no more than an indicator of soil
>health, in the same way that the temperature of a human body indicates
>whether it is well or not. Plenty of earthworms would indicate to me
>that the coffee grounds cannot be making the soil very acid, a condition
>they do not like.
>
>It was long thought, for instance, that pine needles would always
>acidify a soil, but experiments using them as mulch in gardens and
>adding them to compost heaps, has now shown not to be the case. The
>acidity of some soils where pines for instance grow is then probably due
>to the particular soil flora in the area, with usually a predominence of
>fungi which live more happily where conditions are acid. In gardens,
>where there are more bacteria in the soil populations the development
>of acidity is much more unlikely whatever organic materials are applied.
>If I were using a lot of coffee grounds I would be more concerned to
>balance them with enough carbon to mop up all that lovely nitrogen
>before it escapes into the air as ammonia.
>
>I have ceased to worry about pH in my own garden, though I occasionally
>add a little lime to vegetable beds, more to ensure the soil has
>sufficient calcium than for any effect on the reaction of the soil.
>
>Moira
Moira:
Acidity from organic sources will only be transient in any case. When
hydrocarbons oxidize on their way to becoming water and carbon dioxide, the
next to last step is to form an organic acid. These do not accumulate, but
go on and oxidize further. It is the non-carbon elements like sulfur and
phosphorus that generate persistent acids. Adding a small amount of lime
keeps these in control, and seasons the broth, so to speak, so that
micronutrients such as boron, zinc, copper, and selenium are available at
appropriate levels. The so-called humic acids are the breakdown products of
lignins that hold nutrients in place in the soil by acting as chelating
(from the Greek meaning claw) agents.
Richard F. Dufresne
313 Spur Road
Greensboro, North Carolina 27406 USA
336-674-3105
