I am looking for suggestions to remediate compacted soil (the soil is somewhat high in clay content and has a neutral pH). I am helping to start a food forest and vineyard on 19 acres on the outskirts of Atlanta. The owners of the land want to host weddings and events, and (against my advice and wishes) graded the entire area designated to become a muscadine orchard to level it out. The soil has been compacted considerably. Any suggestions for starting to heal the damage that has been done? We are planning to add compost and cover crop the entire area, and hold off on planting grapes for now. Suggestions for cover crops for this situation? Any other advice? Thank you.
A heavy layer of wood chip mulch will jumpstart the process, even as it will build a new layer of topsoil that you probably lost when they graded the area. Mulch offers a home to worms and other biota, as well as feeds the fungi as they begin to recolonize your soil. Mulched soil retains moisture at a significantly higher percentage. Mulched soil makes it easier for cover crops and other plants to send roots down into the compacted soil. So, when in doubt, heavily mulch your soil.
As for cover crops, in a sense, any cover crop is going to send a root down into the soil. People swear by tillage radish but I find that it doesn't go very deep into heavy soil before the radish starts to push upward and grow above the soil line. A cover crop mix of grasses and broadleaf plants will help considerably. Go for a mix with at least 10 or more species, as that'll feed your soil (root exudates) and will feed a broader range of microbial life. You should be able to plant a cool season cover crop in fall and leave it out there to do it's thing all winter.
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IF the topsoil has been skimmed off to level the area and all you have left is good ole GA clay I would suggest using a subsoiler first to help break up the compaction then mulching the area heavily with a good compost then letting it lay for a while. GA red clay will literally eat your organic matter. It took me nearly ten years of regularly adding a LOT of organic matter to my garden when we lived in N GA to get it where I wanted it and then regularly adding additional yearly "supplements" of compost and other organic matter to maintain it. I grew up in the mountains of N GA and do have some experience with red clay. It is super as far as minerals etc, but it will set up like concrete when it gets hot and dry without sufficient organic matter.
As far as plantings for it I would look at some of the mixes that are used for deer food plots. I used to plant oats, annual ryegrass and clover. That with the addition of turnips, tillage radish or other root crops will help add more organic matter and nutrients with the added benefit of helping the soil loosen up. Watch the ph of that soil as red clay tends to be or become acidic. Do take a soil test and see where you stand before starting any fertilization program.
Jude Della Terra wrote:I am looking for suggestions to remediate compacted soil (the soil is somewhat high in clay content and has a neutral pH). I am helping to start a food forest and vineyard on 19 acres on the outskirts of Atlanta. The owners of the land want to host weddings and events, and (against my advice and wishes) graded the entire area designated to become a muscadine orchard to level it out. The soil has been compacted considerably. Any suggestions for starting to heal the damage that has been done? We are planning to add compost and cover crop the entire area, and hold off on planting grapes for now. Suggestions for cover crops for this situation? Any other advice? Thank you.
What happened to compact the soil? Compacted soil usually has been subjected to long term heavy equipment usage.
Many times I go to help with compacted soil that is really just Tight soil structure, compacted soil will not let any water seep in, is usually below the surface and might be feet thick or just inches thick.
The number one thing to do in any soil remediation is to get plants growing so the root systems can add organic material and exudates which will bring in the bacteria, fungi and other microorganisms.
If the soil is mostly clay you might want to make an addition of gypsum then a 2-4 inch thick layer of wood chip mulch or compost should you have that.
Compost teas sprayed over wood chips does wonders to all soils but especially clays, this gets humic material as well as humic acid soaking in.
If you can do all these things the soil can start loosening up very quickly (2-3 months) and it will only get better as you continue to help the soil recover.
Marco's tips are super by the way.
Walt gave some good plant selections to get those all important roots in so you can get the soil going.
any organic matter you have access to - mulch is your friend here.
ferments and natural farming techniques may interest you. the main gist of natural farming is that with the fermented plant extracts, bokashi, etc...all rich with micro organism and mycorrhizal networks and IMO (indigenous microorganisms) will cause the soil to swell and loosen...without any tilling...
You best bet is to just subsoil it; a cheap and easy implement to buy and operate. The key is set-up, getting the tip just right so it sinks into the ground and makes the work easier on the tractor. Set the top link wrong and the tractor works, the sub soiler brings soil to the top and it looks horrid. But when done right it looks good, and the soil is really fractured.
As others have said though, it might not be that compacted. If the used tracked machines the ground pressure is less than a human footprint, my bulldozer was around 5 pounds per square inch. I could drive over mud I could not walk through.
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