Phytoremediation plan: Any critiques?

Long post, any soil nerds care to weigh in?

My soil tests indicated that I have crazily high levels of copper, zinc, phosphorus, and potassium. And unfortunately, I also have lead levels that are well above the normal range. Most recommendations I’ve read say I shouldn’t plant food crops in it.

Replacing the soil isn’t an option as I already have many things planted in the soil, including fruit and nut trees. Interestingly, everything except for a few of my currant bushes looks pretty healthy.

I realize the phytoremediation (removing lead and other heavy metals with plants) is a slow process that takes years, and it’s possible I will never be able to plant edible leafy greens in this soil if I want to harvest and use them. I have a plan to tissue test some herbs and berries grown in the soil to see how much lead is making it into them, then make more decisions after that.

For now, here’s what I’m doing;

• In the contaminated section, I am not doing any chop and drop
• Instead, anything I chop gets isolated and composted away from my garden in a place where I don’t plan to plant at all—and the compost won’t get used anywhere else either
• In the fall, I will make up for the loss of dead material by collecting loads of leaf litter from around the neighborhood, shredding the leaves so they don’t form a dense mat during our rainy winters and prevent oxygen exchange
• I have planted dynamic accumulators like comfrey and clover, which I am regularly picking/chopping and disposing
• I am planting a handful of sunflowers each year and disposing of the stalks, since they’re known superaccumulators that take up lead in the soil
• My annual crops are all in raised beds
• Someone has suggested adding biochar as this has the possible ability to tie up heavy metals in the soil, but I haven’t adequately researched this yet
• In a few more years I plan to retest the soil and see if any progress has been made on decreasing the levels of the elements listed above

Any thoughts? Anything I haven’t considered?