Phytoremediation of Heavy Metals

ArtemisiaVulgaris

Mugwort (Artemisia vulgaris)

Us city slickers have fouled the sandboxes we play in. Find an open field in a big city like Los Angeles or New York and the odds are that it’s a former toxic waste dump. Here in our neighborhood we’ve got a lot of lead and zinc–lead from paint and gasoline and zinc from brake linings.

These heavy metals don’t magically go away. They are elements, and short of an alchemical transformation you have to physically remove them, cover them up, or apply phosphate so that plants don’t take them up as readily.

One promising strategy is phytoremediation, the use of plants to uptake heavy metals. City Atlas youarethecity, in New York, is experimenting with Indian mustard, mugwort, basket willow and sunflowers to remediate a contaminated garden. The results are promising with some metals down 50% in a year. Mugwort (Artimesia vulgaris) did an especially good job with a wide range of contaminants.

I should note that Garm Wallace, who runs Wallace Labs, a soil testing service, says that phytoremediation can take many years to get heavy metals down to a safe level. That being said, breeding plants specifically for heavy metal hyperaccumulation is a technology that could make up for our past transgressions.

Thanks to Michael Tortorello for the tip.

How to Search for Science-Based Gardening Advice

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Agricola’s search page.

In the course of writing our books and this blog we’ve had to deal with a lot of thorny gardening questions such as the effectiveness of double digging, the toxicity of persimmons, compost tea, lasagna gardening and how to mulch to name just a few. While the internet is an amazing tool, the number of conflicting commercial interests, biases and crazy talk in the eGardening world can make it difficult to, as Mark Twain put it, “corral the truth.” And I have to confess to promulgating some of the questionable advice that’s out there.

In the interest of not spreading more bad information Linda Chalker-Scott, Extension Horticulturist and Associate Professor at Washington State University, did a webinar (archived online here) with a lot of great advice on how you can evaluate gardening advice as well as do your own searches of peer reviewed literature.

Continue reading…

Saturday Linkages: Rammed Earth, Vanilla Ice and Moonshine

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Best idea of the week. Image: Natural Building Blog

Smokeless Rammed Earth Stove http://feedly.com/e/3e4xRBr8 

Ice Goes Amish: http://modernfarmer.com/2014/02/vanilla-ice-amish-farmer/ …

Plastic debris for brains http://www.honeybeesuite.com/plastic-debris-for-brains/ …

RiYL podcast 041: Colin Spoelman, moonshine maker: http://boingboing.net/2014/02/20/riyl-podcast-041-colin-spoelm.html …

Brazil’s new dietary guidelines: food-based! http://feedly.com/e/xL8TJUJf 

Austrian Designer Upcycles Bike Parts into Faux Hunting Trophy Bicycle Mounts http://inhabitat.com/austrian-design-upcycles-bike-parts-into-faux-hunting-trophy-bicycle-mounts/ …

How Would You Drive If Your Child Was Crossing the Street in Front of You? http://feedly.com/e/6MzdiI4- 

Meet the Miller: Nan Kohler http://feedly.com/e/oWHthiZg 

Meet the Baker: Dave Miller http://www.farine-mc.com/2014/02/meet-baker-dave-miller.html?spref=tw …

Flower Mandalas: http://boingboing.net/2014/02/17/flower-mandalas.html …

Fallout shelter originally installed in 1955 for a family of three in Fort Wayne, Indiana. http://feedly.com/e/1vhqFO23 

For these links and more, follow Root Simple on Twitter:

Advantages and Disadvantages of Raised Bed Vegetable Gardening

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The new hexagonal raised beds. More on the design in another post.

Due to contaminated Los Angeles soil, we’ve got to grow our veggies in raised beds. There’s just too much lead and zinc in the ground, according to our local soil lab. Putting together three new beds recently got me to thinking about the ups and downs of gardening in raised beds. I thought I’d list off the pros and cons:

Pros:

  • Keeps roots away from contaminated soil.
  • Good for disabled or elderly gardeners.
  • Neat.
  • If high enough, can keep out some critters–and keep veggies above the dog pee zone.
  • Plug and play–no need to build or improve soil.
  • Keeps roots from getting waterlogged in a wet climate.

Cons

  • Requires materials to construct.
  • Might need to buy soil–gardening in the ground is free.
  • Roots dry out quicker in a hot climate.
  • Lack of mineral content in bagged soils.
  • Use of peat moss in bagged products.
  • Unable to truly embrace the “no dig” philosophy: despite best efforts to the contrary, it seems the soil needs to be swapped out every few years. It’s container gardening, really.

Going through that list of pros and cons, if it weren’t for our contaminated soil it would be better for us to grow in the ground. From a water use perspective, in Mediterranean climates such as ours, it’s better to garden at ground level. Less evaporation.  In dry desert climates such as New Mexico it’s often better to garden slightly below grade to take advantage of summer rains. Conversely, in soggy climates raised beds have some advantages.

Another factor is cost.  A bulk soil order doesn’t start to make sense until you’ve got a lot of raised beds to fill or neighbors to split the order with. This leaves me stuck with bagged products. I’m testing out a variation on Mel’s mix: one part coconut coir, one part vermiculite, one part compost. It’s still expensive, but at least I’m weaning myself from peat moss, an unsustainable product. Unfortunately, all those bags have to be hauled up thirty steps.

As a whole, what we’ve done with our garden is a compromise. Most of the yard is permaculturish: lots of small fruit trees, some native plants, ornamental flowering plants for the wildlife and a whole lot of mulch. But I like to have a few Italian veggies so we’ve got five small raised beds.

Did I leave anything off this list of raised bed pros and cons? What are you growing your veggies in? Leave a comment!