Phytoextraction techniques utilizing a sterile strain of Vetiver grass (Vetiveria Chrysopogon zizanoides) along with soil amendments were evaluated for removing lead and other elements such as Zn, Cu, and Fe from the soil of a 50-year old active firing range at the Savannah River Site (SRS). Lead-contaminated soil (300–4500 ppm/kg) was collected, dried, placed in pots, fertilized, and used as a medium for growing transplanted Vetiver grass plants in a greenhouse. The uptake of metals by the plants was evaluated in response to various fertilization and pre-harvest treatment schemes. Baseline metal concentrations in the soil of all pots were measured prior to planting and when the plants were harvested. Plants grew better when fertilized with Osmocote® fertilizer in comparison to plants fertilized with 10-10-10 (NPK) fertilizer. Application of a chelating agent, EDTA, one week prior to harvest significantly increased the amount of lead that was phytoextracted. Lead concentrations of up to 1390–1450 ppm/kg in tissue samples were detected. Maximum Pb levels were observed in root tissues. The addition of non-lethal doses of a slow-release herbicide in combination with EDTA did not appear to further enhance phytoextraction or the translocation of Pb into shoots. The study indicated that the use of Vetiver grass coupled with the use of chelating soil amendments has considerable potential for use as a remedial strategy for lead-contaminated soils such as those associated with firing ranges.
This is really cool! I wonder how well adding fulvic acid in lieu of edta would work
I just posted another study involving compost/biochar locking up metals.
It would probably help?
I literally just bookmarked that! Thank you!
My state has just revamped, and made much more strict, their heavy metal testing requirements for my industry. Lots of my colleagues have just started failing those tests. As an organic grower, I’m going to need some new tools and techniques in my arsenal.
What media are they using and failing on?
Some in pure coco coir, some in commercial potting mixes. I’m sure their liquid fertilizers are playing a part in that too tho.
But, I worry about my soil here because I often amend with glacial rock dust, which has a bit of heavy metals in it as well
You think the fert over the Coir is more likely? I suppose where the coir is harvested from could be an issue when we are in a thread talking about accumulators.
I saw a photo of yours and I didn’t follow it up, are you growing in beds or cycling pots? When do you start your testing? Are you considering char? How often do you need to realistically rock dust?
I don’t know enough about their methods to say for sure. I do know where my worries are tho.
We grow in beds. We don’t test our soil often enough unfortunately, tho that’s going to change now. The state’s heavy metal testing has already started and we just harvested.
I’ve known about biochar but haven’t thought about a real need for it. This new info to me has already changed my mind tho. I tend to add the rock dust at 1/4 - 1/3 of the recommended dosage every other crop, since that’s my only source for most micro nutrients.
I’ll try to make a new post tomorrow with our most recent soil test results, the heavy metal analysis for the rock dust, and some more info and better questions.
