Lawrence F. London, Jr.
london at sunsite.unc.edu
Sat Nov 1 23:36:05 EST 1997
On Sat, 1 Nov 1997, Jack Rowe wrote:
> I can believe that to-us subtle changes in light frequencies can have an
> effect on seed germination... what appear to be small initial influences
> can often result in profound changes in outcome. This mechanism might
> prevent weed seeds (which are often impressively-long-lived) from
> germinating before the canopy is opened above them or they are carried on a
> hog snout out into the open and replanted.
> A lot of weed seeds have two dormancy requirements. The first is a ripening
> or maturation stage, which they spend underground or out of the light. The
> second requirement can then be satisfied by exposure to light. This is true
> of a lot of amaranthus', for instance, and Chenopdiums. This is the reason
> for the common name "pigweed", historically applied to both these genera...
> these plants are often germinated by rooting pigs, who expose mature seeds
> to light in the course of their rooting and so cause their germination.
> These are called weeds of disturbed soil and they tend to be fast-growing,
> tolerant of poor soil, and fast to produce huge quantities of tiny seeds.
> In the case of the two I mentioned, good eatin', too.
> This makes a good argument for constant-mulched, no-till gardening, as does
> the erosion cited by Dan, as does simple ergonomic sanity. Rodale Inst., by
> the way, has found a great decline in the germination of weed seed
> resulting from soil disturbance, if weeding and/or digging is done at
> night, and soil thus disturbed is re-mulched before daylight returns.
Then, in preparing new ground for permanent no-till raised beds that has a
large weed seed bank containing, possibly, many seeds of real problem
plants such as crabgrass [not Bermuda], Johnson grass, pigweed, amaranth,
lambs quarters, something I call "false croton", daisies, ragweed, fescue,
ryegrass or goldenrod it would seem practical to till the ground and _sow
it with lambs quarters_. This plant would quickly grow to form a canopy
to shade other emerging weeds below. The reason I suggest lambs quarters
is that, this year, I have seen it growing in an area where I tilled
in a big pile of cow manure pile. These plants quickly formed a canopy
and outcompeted amaranth, fescue and Bermuda!; in fact the ground beneath
the plants was barren except for the leaf litter from the l.q. This plant
either creates exceptional shade or is highly allelopathic or both.
So, new turf with high weed seed count could be cleaned quickly with
brief tillage and successive plantings of l.q. repeated over and over
as many times as is possible in a growing season. A typical permaculture
solution to bed prep, weed control and generation of human and livestock
feed, and compost, of course. Maybe amaranth would be a better choice of
plant material except that its not as tasty in salads as l.q. but puts out
more seeds for later plantings.
What would be a better cover crop to clean weed infested turf?
More information about the permaculture