Thursday, January 31, 2013

Roundup® doesn’t help maintain gravel

It took a few years to figure it out, but I’m ready to pronounce Roundup® and all other glyphosate herbicides useless, even counter-productive, in maintaining clean gravel.  Pulling weeds in flower is my most efficient way to control weeds in gravel.  
Gravel has to be maintained clean, or it disappears under plants and the soil that forms from organic matter and dust.  Plants add to the organic matter if they are allowed to die in place; they obviously detract from the gravel’s appearance.  Organic matter and dust can be regularly blown off, but plants are not so easy to move.
The key to controlling plants in gravel is reducing fertility, surface soil, and seeds.  Glyphosate adds to the first, as it’s a powerful crude organic fertilizer that preferentially grows broadleaf flowering plants because it’s high in nitrogen and phosphate.  But it also does not reduce seed load from the worst of the annual weeds, and makes them harder to weed out.  On the less-packed margins, it feeds worms that bring soil to the surface.
Annuals live to make seed, their only means of reproduction.  They grow a lot of root to support leaf growth when they are young; as they flower, they turn most of the mass of that root into stalks, flowers, and seeds.  Some can live off the water and proteins in their roots and leaves as the soil dries out, if you pull them and leave them lying on the ground, or if you kill their root tips with glyphosate. 
Some annuals, like bitter cress, miners’ lettuce, annual rye, and crawling knotweed, don’t die when hit with glyphosate; they immediately stop growing leaves and go to flower and seed, no matter how young they are, and they ripen those seeds.  When their root tips die because the glyphosate amino acid doesn’t fit in their new proteins, they use the good proteins in their remaining root and leaves to grow flowers and ripen seeds, which are therefore quite viable.
Plants crowd each other out with the help of bugs that eat smaller, stressed plants.  If hit with glyphosate, they don’t grow large and don’t crowd each other out, so one ends up with many very small weeds, hard to see and tedious to pull.  While the plants may not grow large, their aggregate mass still adds to the organic load and the seed load nearly as much as unsprayed plants. 
Unsprayed plants are a lot easier to pull, as they are larger and there are far fewer of them.  It is far easier to pull them in maturity than earlier, as the stalks are strong and easy to grab and the root is shrunken.  Nor does one have to pull the reduced root.  Most annuals in full bloom will not return if the top breaks off the root.
If your gravel is showing a lot of soil or is buried under plants and organic matter, it is best to cover it with fresh gravel, either crushed clean or small river gravel.  Avoid any “minus” crushed gravel, as it is full of fine mineral soil.  It’s a lot easier to blow leaves off of clean gravel than soil, as leaves really stick to soil.  Clean gravel grows a lot fewer weeds, as most need soil and a touch of sun to germinate.  It’s much easier to see the weeds and pull them as they flower.  And it looks really nice.  It’s far easier and much more gratifying to keep clean gravel clean than to clean up buried gravel.
Published at Yahoo Voices under Natural Gardener Report. 

1 comment:

  1. Crushed clean gravel was one of the worst mistakes I made, mainly because I now prefer 4 x 8 sand, actually the "small river gravel" I mentioned, 1/4-1/8 inch, which can be easily maintained with a hula hoe and rake.

    But to transition from the former to the latter, I have to cover the crushed clean (now quite dirty and full of weeds) with soil and then put down the smaller gravel. Otherwise, the larger rocks will rise through the smaller ones and end up on the surface.