I’m expanding the garden another 200sq feet and was curious about my soil ph and fertility. I know I plant in a clay soil with low fertility but I wasn’t prepared for how bad it really was. Clay content damn near 100%, ph just shy of 8, and overall fertility is abysmal. It was corn ground from the mid 1800’s to the 1960’s when all the topsoil was bulldozed into the neighboring valley for subdivisions. My lot is a half acre of clay and turfgrass laid over it.
This is where I plan to document my progress of remediating the soil, through poly culture. I’ve roto-tilled about 8 inches down and in a couple days tilling in whatever organic matter I can scrape up to lower the ph value.
I’ll be companion planting my nitrogen fixing corn landrace, my cow pea landrace Ive selected previously for this same companion planting, and various common pole beans to increase fertility. I’ll also be growing a sunflower landrace from the around the border for its apparent allelopathic ability to see how well it keeps out the creeping charley. The plan is to repeatedly chop and drop mulch everything together at the end of every year.
Possibly try sweet potatoes for soil remediation. Anything that gets down into your soil will rot over the winter and leave nice little pockets of organics in the clay. Just harvest enough to start over the next year.
The garden I first established in this house’s yard is needing some love. It was graded with red clay, and its just awful stuff with no fertility at all by my simple probe test (it gives a simple "not fertile, fertile, very fertile pointer). Between compost, woodchips, and growing anything that will survive there its better 2 years later. But still needs love. Just remember that it will take a while to get it right!
There’s a “Nitro Radish” you can get seeds in bulk at ag supply or ag seed stores. It’s a daikon cover crop. Daikon has deep roots and breaks up clay. Also consider clover or other cover crops. Ideally, look for local agricultural vendors because mail order is going to be far more expensive for bulk seed, which is the quantity you need. A seasonal rotation, for several years will dramatically improve even poor soil.
I also like to inoculate my soil on an ongoing basis with healthy soil from other locations. Even a few handfuls of dirt scattered about, particularly just before rain, can do a lot of good introducing the soil organisms that are lacking.
Also you could shortcut the process by paying for a dumptruck load of finished compost and then till it in. If your budget allows for that, it’s probably your best option. That is what we do for Giving Gardens. It’s about $1500 for 40 cubic yards delivered. That’s a semi trailer full. Worth it.