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  • From: Lawrence London <lfljvenaura@gmail.com>
  • To: sustagnet@googlegroups.com, permaculture <permaculture@lists.ibiblio.org>
  • Subject: [permaculture] Studies on the double digging gardening method.
  • Date: Thu, 28 Mar 2019 16:00:30 -0400

Studies on the double digging gardening method.
http://www.ibiblio.org/london/orgfarm/double-digging.txt

Date: Mon, 4 Jun 2001 09:19:02 -0700
Reply-To: amcguire@coopext.cahe.wsu.edu
Sender: Sustainable Agriculture Network Discussion Group
<SANET-MG@LISTS.IFAS.UFL.EDU>
From: Andy McGuire <amcguire@COOPEXT.CAHE.WSU.EDU>
Subject: Double Digging study
In-Reply-To: <aa.16510607.284b6fd8@aol.com>
Content-Type: text/plain; charset="us-ascii"

Here is one study that looked at double digging:

Author(s): Holt, B.F. ; Smith, I.K.
Title: Small-scale intensive cultivation methods: the
effects of deep hand tillage on the productivity of bush
beans and red beets.
Source: American journal of alternative agriculture. 13, no.
1 (1998): p. 29-39.
Additional Info: Greenbelt, MD : Henry A. Wallace Institute
for Alternative Agriculture. Publishing Agencies: US
Imprint, not USDA
Standard No: ISSN: 0889-1893
Language: English
Abstract: This study examined how one aspect of intensive
cultivation, double digging by hand (loosening the planting
bed to 50 cm deep), contributed to crop productivity and
nutrient uptake in bush beans (1994 and 1995) and red beets
(1995 only). Comparison beds were prepared with the soil
cultivated to 25 cm (single dig) and 6 cm (surface
cultivation). Although there were significant differences
(1994 beans) between the surface cultivated beds and other
cultivation types for leaf mass and chlorophyll content,
there were no significant differences in the total mass of
beans (whole fruit) produced. There were no significant
differences in beet green or root (edible portion) biomass
among cultivation methods. Levels of Ca, Mg, and K in the
bean fruits and beet roots were not significantly different
among cultivation methods. This study demonstrated that deep
cultivation significantly alters the soil profile as
measured by penetrometer resistance, but that this change
does not necessarily alter productivity or nutrient uptake.
We suggest that deep hand tillage has little effect on crop
productivity in well-watered and moderate to high fertility
soils. These results are similar to those found in
mechanically subsoiled systems.




Date: Mon, 4 Jun 2001 12:17:52 -0600
Reply-To: steved@ncatark.uark.edu
Sender: Sustainable Agriculture Network Discussion Group
<SANET-MG@LISTS.IFAS.UFL.EDU>
Comments: Authenticated sender is <steved@ncatark.uark.edu>
From: Steve Diver <steved@NCATARK.UARK.EDU>
Subject: Re: Double Digging
Comments: cc: CAVM@AOL.COM
In-Reply-To: <aa.16510607.284b6fd8@aol.com>

CAVM@AOL.COM wrote:
> I know it is almost a sin to make assertions without cites but I can not
> recall where I read a few weeks ago about a test done with single digging
> of
> a garden and double digging. The double digging did no better but was
> considerably more work.

The American Journal of Alternative Agriculture featured a paper
in 1998 that summarized research on double digging in comparison to
single digging.

Holt, Ben F., and Ivan K. Smith. 1998. Small-scale, intensive
cultivation methods: The effects of deep hand tillage on the
productivity of bush beans and red beets. Am. J. Alt. Agric.
Vol. 13, No. 1. p. 28-39.

Table of Contents online:
American Journal of Alternative Agriculture
http://www.winrock.org/wallacecenter/ajaa.htm

Intro to Abstract:
"This study examined how one aspect of intensive cultivation, double
digging (loosening the planting bed to 50 cm deep), contributed to
crop productivity and nutrient uptake in bush beans (1994 and 1995)
and red beets (1995 only). Comparison beds were prepared with the
soil cultivated to 25 cm (single dig) and 6 cm (surface
cultivation)."

Conclusion to Abstract:
"This study demonstrated that deep cultivation significantly alters
the soil profile as measured by penetrometer resistance, but that
this change does not necessarily alter productivity or nutrient
updake. We suggest that deep hand tillage has little effect on crop
productivity in well-watered and moderate to high fertility soils.
These results are similar to those found in mechanically subsoiled
systems."

Excerpt from Conclusion:
"Because of the high labor and energy costs of double digging, the
results from this study suggest that it should be avoided in
locations with sufficient rainfall, moderate to high soil fertility,
and no definite root-restricting soil horizons. Because the effects
of deep hand tillage have received little attention to date, we
designed this study as a starting point for further research. Plants
were given sufficient nutrients and moisture. The present study does
not address plant productivity under severely limited supplies of
nutrients or moisture, an area that clearly requires further
investigation. Where there are restricting horizons or resource
limitations, the small-scale farmer might consider double digging
once, followed by continued proper bed management."

Some comments:

The largest commercial biointensive farm I've encountered was a
1 acre organic market farm in California, where the intensive
double digging was peformed by hired Mexican labor.

Alex McGregror's biointensive mini-farm in Tenneesse is the one
that comes to mind as a practical example of the John Jeavon's
biointensive model in action, modified according to fit Alex's
ideas and resources.

Alex gave a presentation to a room-packed audience at the Southern
SAWG conference in January, 2001. My recollection is that he follows
something very close to what the conclusion to the AJAA article above
said, "the small-scale farmer might consider double digging once,
followed by continued proper bed management"; i.e., he double digs
the first year only.

Incidentally, Timberleaf Soil Testing Lab in California offers a soil
test that is specifically geared to biointensive market farming.
This soil test grew out of Steve Rioch's program at Ohio State
University.

Steve Diver


Date: Tue, 5 Jun 2001 09:27:57 -0400
Reply-To: Sustainable Agriculture Network Discussion Group
<SANET-MG@LISTS.IFAS.UFL.EDU>
Sender: Sustainable Agriculture Network Discussion Group
<SANET-MG@LISTS.IFAS.UFL.EDU>
From: Alex McGregor <waldenfarm@SPRINTMAIL.COM>
Organization: Walden Farm
Subject: Re: Double Digging
Content-Type: text/plain; charset=us-ascii

Steve & Andy,

Thanks for pointing out the reference. This is the only scientific research
I
know of about "double digging." I would like to point out a few
things about this
paper.

1. These comparisons were done using beans and beets- selected by Ben
and Ivan to
represent fruit and root crops. The flaw here is that both these do
not require
peak fertility to produce a crop. This was pointed out to me (and
Ben) by Steve
Rioch. Steve suggested they use carrots as the root crop and a
non-legume for the
fruit; that is, a high nutrient & high fertility demanding plant.

2. Please note in the conclusion the part about high fertility and adequate
moisture. Jeavons' work started in soil that had been graded below the
subsoil
level and in an area of California with low rainfall. He developed
his techniques
to match these. My point is that no type of agriculture should be
considered an
orthodox religion. It needs to be applied to match soil, climate, crops and
resources.

3. Ben didn't use Steve as a resource for this study. He had had a falling
out
with Steve and changed his Master's program from Biointensive to
Botany. I taught
the Garden portion of Steve and Ivan's classes during these years and
talked with
Ben about his research. I found him to be an angry young man who had
concluded
that "Biointensive doesn't work" before the research was concluded.

Alex McGregor
Walden Farm



  • [permaculture] Studies on the double digging gardening method., Lawrence London, 03/28/2019

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