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Reed Canary Grass and heavy clay from pond got put on garden

Baraboo, WI

OMG! Last spring, my husband's brother was trying to be helpful when he scooped out our pond he put the heavy clay filled with Reed Canary Grass (RCG) onto my vegetable garden. We used corn gluten to try to prevent the seeds from sprouting and it worked to a limited degree. We still have a lot of the RCG and the clay is almost impenetrable to normal plants, of course, weeds seem fine with it. This garden was an organic "lasagna garden" using sheet mulch and was very fertile. Any ideas on how I can get my garden back? I'm willing to put it out of commision for a few years if I have to as I have another, albeit smaller and less fertile garden. I would prefer to not use pesticides as that is one of the main reasons I get abundant, nutritious, organic produce.
Thanks for your help!

Everett, WA(Zone 8a)

I was hoping it was SILT (fine organic slop that packs tight but will be rapidly eaten by worms and bacteria). But it sounds like you got literal clay.

All these suggestions are just what I think, and balance that against other suggestions. And the next paragraph is probably NOT good to try unless you have SUPER-light, super-organic and very deep clay-free soil that is 14-18" deep already.

IF your bed was very rich in organics AND had plenty of grit and roots AND great aeration and excellent drainage, you MIGHT be able to just mix the top 1-2 inches of clay with 16 inches of loose, light soil, and wind up with 18" of something that might be a little heavy but is still open and draining ENOUGH. You said "lasagna garden" so maybe it is deep, 80% organic compost that can absorb and dilute lots of clay and still be good soil.

BUT if you have too much clay and not deep enough organics and grit and sand, you might make it ALL impenetrable clay and that would be awful.

I would try amending the top layer of clay in place and making it at least half-decent before mixing it into the rest of your GOOD soil underneath.

You might even shovel OFF the top 1-2 inches, move it elsewhere, and amend it SOMEWHERE ELSE. Then wheelbarrow it back or make more beds with it AFTER amending it.

If total removal is too much work, try to amend it in place before rain makes the clay sift out of the top layer and clog up your entire soil layer.

First and foremost: add LOTS of compost or raw organic matter, both mixed with the clay layer and sheet-composted on top of it. Add still MORE compost. Mix it with the clay .

Probably mixing coarse pine bark mulch, other conifer bark mulch, small bark nuggets, grit and coarse sand INTO the surface clay layer will help with aeration (especially for the first year or three). That helps to open it up and fluff it up, creating "structure", at least temporarily. .

Mix with a fork and spade and hoe and cultivator (or roto-tiller) to "fluff up" the mix while fairly dry. Tamp gently (dry) to try to enforce some structure before it gets wet and "runs".

NEVER DO THAT WET! Working wet clay will remove all the air and "structure" and turn it into pudding or concrete. Even if you have to spread tarps or plastic film, keep the heavy clay mix from getting too wet. If the clay is still soupy or "pudding-y", and it gets, it will settle, the air and structure will be squeezed out, and you'll have an airless dead mass.

Keep adding more compost as often as time and energy allow. Organic matter feeds the fungus and bacteria and worms that will maintain the mechanical structure that you tried to create while fluffing it up like an omelet.

If you have patience, the easiest and cheapest way to add organic matter is to plant cover crops. Clover, winter rye, buckwheat, alfalfa, vetch, mixes with peas or other N-fixers, whatever your local feed store stocks the most of is probably best for your region. Ask or do research to find out what good local cover crops deal best with a top-layer of clay. Maybe something with lots of fine surface roots to start with. You don't need them to dig deep like tillage radishes or alfalfa, just a really tight network of fine feeder roots neat the surface to break up the clay and choke the RCG.

And it will be fun to buy FIVE POUNDS of seeds for a few bucks or less per POUND. The roots and tops are both good organic matter. Roots will penetrate the clay unless it is already concrete, and maybe then

You might even find something that chokes out your RCG From Heck. Three crops of cover crops per year, plus weeding the RCG and maybe 1-2 mowings ought to give the unwanted grass some competition.

And the feed store clerk may have suggestions for choking out your local weeds. Solarization after the soil is semi-well aerated? That will also help keep it from getting too wet.

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