[permaculture] Weed removal
Lawrence F. London, Jr.
lfl at intrex.net
Tue Apr 4 12:58:55 EDT 2006
Jerome Rigot wrote:
> Johnson grass is similar to Bermuda grass in that it also spread
> rapidly and aggressively by rhizomes, and very effectively by seeds
> (one plant can produce over 5000 seeds per year and these seeds can
> lay dormant in the soil for over 20 years, so cutting the seed head
> before seed maturity is really important). The plant was introduced
> from the Mediterranean as a gift to a Mississipi plantation owner
> over 150 years ago to use as hay. A major problem is that under
> stress it will produce an acid that is poisonous to livestock. It
> also releases a natural toxin from its root system that prevent other
> plants from growing close to it, a natural herbicide, so to speak. It
> has a shallow root system that does not do anything to aerate the
> soil or to improve drainage as prairie grass does. It grows very
> tall, completely smother other plants and "it has literally destroyed
> millions of acres and bankrupted thousands of family farmers in its
> march across the land. Suffolk County in West Virginia has made it
> against the law to have even a single Johnson Grass plant on your
> land because it is so destructive to farmland." You can read more
> about it at http://www.seedsource.com/medicine/curse.htm.
There's another problem with Johnson Grass and that is its interbreeding with other sorghum varieties
like grain sorghum, the shattercane syndrome. This means that harvestable seed will be prone
to dislodging from plants prematurely, i.e. drying and fallling from the plants. This makes mechanical harvesting
difficult because the seeds will fly off the plant at the least provocation before the combine can glean them to
put into storage. Johnson Grass does this naturally and is imparting this property to economic grain crops in its plant
> I know that one of permaculture mantra is that "the problem is the
> solution", but I I don't think using Johnson grass as a natural
> herbicide to get rid of my other "weed" problem in my garden would be
> a very wise strategy. And both weeds are not that edible.
> In any case, when LL mentioned that he got rid of Johnson grass and
> Bermuda grass, my ears perked up, because they are very serious
> non-native invasive pests that are surrounding and attempting to
> invade my garden.
> I am still interested in hearing his approach as well as anybody
> else's practical suggestions.
I have actually done it. Of course this summer's cropping will reveal
the remaining weed seed bank and weed rhizomes.
I began by improving my farm soil with rock dusts, manures, composts
and tilled under cover crops and weeds. I then created long rows of parallel raised beds.
Some blocks of the rows were perpendicular to other blocks of rows. When I did not get crops
planted in much of these areas many billions of weed seeds germinated and matured to full sized plants
which then set seed that fell to the ground - weeds I encountered are in this list in varying proportions
and during different times of the seasons:
Johnson Grass, Bermuda Grass, Pennsylvania Smartweed, crabgrass,
daisies, ragweed and goldenrod, thorny pigweed, Carolina horse nettle, curly dock, amaranth, lambs quarters,
ryegrass, fescue grass, wild mustard, datura a mystery weed
When I procured a large tractor, bottom plows, rotovator, 7 tined field cultivator, Yeoman's plow and a large 1100lb
4-disc hiller-bedder on an 8' toolbar (used for making large, high riased beds) I reworked all my fields and laid all
the rows of raised beds parallel to each other and running the entire lengths of each field, often with the grade
(I created large water/nutrient catchments, dams and swales at the bottoms of each field to catch any water and silt
(often very little)). During this process I create newly-formed and shaped large raised beds. Tillage involved
bottom plowing, field cultivating, rotovating, hilling-bedding, rotovating, field cultivating, hilling-bedding
and sometimes light rotovating or field cultivating again. Often this entire process was repeated several times over
in order to get the beds high and wide enough and to pulverize large chunks of dirt. As the seasons and years
progressed the soil mellowed out considerably (I had previously helped this along by adding hundreds of tons of rock
dusts and manure/compost to the soil; this increased water-holding capacity, nutrient levels, and food for
microorganisms and smaller creatures like earthworms). This immense amount of tillage seems to have eliminated most
if not all of the rhizomateous plants and the curly dock (tilled a huge patch of dock under before it could go to seed
again). The annual weeds have been tilled under before going to seed and of course this will be an ongoing maintenance
routine. The weeds (especially in my fertile soil) were very aggressive, grew in populations of great density and to
great size and set an enormous number of seeds. This made vegetable cropping in these gardens difficult or impossible
with weeds outcompeting vegetables for space, nutrients, light and water. There are many non-crop plants that I do not
want to eliminate totally as they are attractive, provide wild food and are beneficial to garden ecology and the ecology
of the entire property. These include ragweed, goldenrod, daisies, dandelion, purslane, lambs quarters, foxtail millet
some greater and leser dock and a number of others. I value my weed seed bank and when/if its gone its gone mostly for
good, short of replanting.
I was especially interested in permanent removal of (in order of priority): Bermuda grass, Johnson grass, Pennsylvania
smartweed, spiny pigweed, rye grass, mystery weed, crabgrass, datura and possibly a few others.
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