Re: no-till gardening
- To: John Schlesinger
- Subject: Re: no-till gardening
- From: r*
- Date: Wed, 15 Dec 1999 15:48:02 -0800 (PST)
See Mel Bartholomew's 'Square Foot Gardening' on taking difficult soil
out of the ground and replacing it with commercial potting mix (not
'potting soil' as there is a big difference). Of course it works, but in
my experience plant growth is the same as in the adobe clay I have broken
my back (almost literally) to bring to a fine tilth with or without
amendments. Obviously the clay contains a good amount of nutrients.
However, since digging out holes and filling with potting mix is akin to
filling large pots with potting mix, I have eventually opted for the
latter because they are movable. And I'm rather pleased with being able
to move things around according to my whims of the moment. I understand
that centuries ago, the Chinese in some parts of their vast lands, opted
for the identical method of dealing with unruly soils. Incidentally, the
woman (can't remember her name at the moment) who created the Barnhaven
Primroses on the southern Oregon Coast advised that the best soil
amendment was pea gravel. Does anyone have experience with going that
route?
On Wed, 15 Dec 1999, John Schlesinger wrote:
> Date: Wed, 15 Dec 1999 06:00:21 -0800
> From: John Schlesinger <johnsaia@dnai.com>
> To: Mediterannean Plants List <medit-plants@ucdavis.edu>
> Subject: Re: no-till gardening
>
> >
>
> Moira -As convincingly you present your case for no-till soil improvement, I have to
> remain a skeptic, at least as it would be applied to heavy clay soil, and especially
> the compacted adobe clay we have in this urban environment. My own personal
> experience with adding woody organic material to adobe clay, has demonstrated that it
> works - in that a friable non-compacting result can be achieved, and rather quickly,
> to whatever depth the matter is added (in sufficient quantity). I should not
> extrapolate this to other clays, as I don't have experience with doing this to them.
> But the black adobe clay we have in California is susceptible do such amendment. (I
> am not a soils scientist - perhaps an expert out there can tell us exactly how the
> adobe clay differs from other clays. It does have a very fine particle size, turns
> to goo when wet, and to brick when dry.)
>
> My basic recommendation for gardeners, is that you don't want to garden in clay, if
> you can help it. In the California adobe areas, there is very little true
> "topsoil". So, for easy gardening, you either grow in raised beds, or change the
> soil beneath the top several inches. By substantially amending the adobe clay of
> California, it becomes tolerable for gardening - (although even I use almost entirely
> organic material for the top 10" or so). Most of the perennials we grow as
> gardeners, have a lot of fine roots in the top 18" or less of soil (a
> simplification, and less so with Mediterranean plants, of course), with most shrubs
> and trees having roots going much deeper into the ground ( they have been adapted to
> grow in compacted soils). The perennials simply grow better in loamy organic
> containing soil than they do in clay. So I maintain that is what you should try to
> give them. It may mean removing the clay, if close enough to the surface, and
> replacing it with whatever you need to get a loamy organically rich soil. I don't
> discount the possibility that worms can carry organic material even into the
> underlying clay, and therefore aerate it, but that is not the same as changing the
> clay into the kind of soil one wants to garden in at the surface level.
>
> As to structure - in the urban environment, where surface clay is compacted, (which
> is what we have in the San Francisco Bay area) there is not a lot of structure - and
> I disagree that spading or tilling is destroying useful structure. I am not talking
> about a natural ecosystem, where the plow has never cut the sod. We don't have that
> in urban California (and probably in many other parts of the urban developed world),
> because wherever housing has been built, the developers scraped the land and
> intentionally compacted the remaining soil, as part of the development process. In
> even slightly hilly areas, this is even legally required, to protect from mudslides.
> Thus there is no natural system left to destroy. In gardening in urban California,
> one has to create a soil structure where none exists. I still remain skeptical that
> this can be accomplished quickly by worms carrying large amounts of surface organic
> material several feet into clay. (I'd love to read the articles you referred to
> about testing in Israel. Could you give me a reference? Were the amounts of
> organic material at various levels below the surface accurately measured? I believe
> you said there was organic material a meter down, but how much?). Also, I don't see
> this happening with sand areas. Barry wrote of an area which I took to be almost
> pure sand. We have that in Golden Gate Park in San Francisco. The entire park, as
> was much of western San Francisco, was originally sand dunes . The park developers
> brought in soil to place over the sand, and there has been heavily mulched parkland
> over most of the area for over 100 years now. Yet, if you dig down, you still find
> the sand dunes underneath, and they are still basically sand. Yes, there is some
> organic material (and silt) mixed in, but not enough that you would call it soil - it
> is still basically sand.
>
> In an area that is principally sand, if you don't change the soil, you will be
> limited to growing what is naturally adapted to sand. So, if one wants to grow
> plants that want a rich soil, why not simply replace the sand with the soil that one
> wants (which is what is accomplished by using a raised bed)? As much as you
> convincingly argue that putting compost material on the surface will change the soil
> beneath, I guess I am just not yet willing to believe that this could make a
> significant difference in pure sand over any reasonable period of time. Maybe Barry,
> you should try this and report back to us.
>
> > >
> > > Richad Starkeson wrote:
> > > But the compost on top of the soil method will take a good deal longer
> > > > than working it into the soil to some depth, and it won't be amended as deep.
> > >
> > Moira Ryan wrote:
> >
> > Strangely, and against all received wisdom and common sense both
> > individual observations and formal experiments disagree with you in
> > this.
> >
> > Field-scale trials in Israel a few years ago were done to find our
> > which was the best way to incorporate organic matter (compost) in soils. They
> > compared conventional ploughing, rototilling and simply applying the
> > compost to the surface.
>
>
>
