Category Archives: Soil & Amendments

It’s found sculpture—it’s a 3-D Rorschach test—no, it’s soil blocks!

I had to look up (i.e., Google) how to spell Rorschach, of course, and amongst the results saw one claiming that most people have never actually seen a Rorschach inkblot. Well, I have. Not that I've taken the test myself; no, that might be dangerous. (Who know what might be revealed?) Instead, I bethought me of Dave Barry's caution regarding a potentially explosive procedure, which I will summarize** thusly: “Do not do this yourself. Instead, send one of your children.”* Yes, when our older son was just six years old, we let a young psych student who lived next door give him a complete Rorschach test. And that has made all the difference.

But truly, this is a post about soil blocks, and these (or those, by now) are indeed soil blocks being protected from cats.

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Readers' Questions: Arsenic from pressure-treated wood, Part I

(My most recent absence can be attributed at least in part to the fact that I, along with most of Bozeman's Symphonic Choir, got up at an appallingly early hour on Saturday morning to catch the bus to Billings for a joint concert. We acquitted ourselves honorably (three standing ovations, though one being for Bach's 4th Brandenburg Concerto which features not a note for singers, it's hard to take credit for all three. I'll give it a try, though: we were eloquent even in silence? No? Anyway, after the reception some of us sang all the way home, arriving at those homes about nineteen hours after we'd left them. Such excursions require a day or two to catch one's breath.)


Last week Jen in Maryland left the following comment on my January post “Compost vs. Arsenic: And the winner is–compost!” about dealing with arsenic in garden soil:

As a gardening novice, I placed a small veggie garden next to an old telephone pole in my backyard. It then dawned on me that maybe the soil could be contaminated with whatever they treated the pole with. The house is 60 years old, so I don't know, but now I'm tempted to give up, for fear of contaminating my family. Advice?

The stuff we are talking about here is the copper chromate arsenate (CCA) that was used as a wood preservative from the 1930s on. By the 70s it had became the outdoor wood-treatment of choice across the United States until concerns that matched Jen's led to its being banned by the EPA, save for a few rare exceptions, in 2003.

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Readers’ Questions: Arsenic from pressure-treated wood, Part I

(My most recent absence can be attributed at least in part to the fact that I, along with most of Bozeman's Symphonic Choir, got up at an appallingly early hour on Saturday morning to catch the bus to Billings for a joint concert. We acquitted ourselves honorably (three standing ovations, though one being for Bach's 4th Brandenburg Concerto which features not a note for singers, it's hard to take credit for all three. I'll give it a try, though: we were eloquent even in silence? No? Anyway, after the reception some of us sang all the way home, arriving at those homes about nineteen hours after we'd left them. Such excursions require a day or two to catch one's breath.)


Last week Jen in Maryland left the following comment on my January post “Compost vs. Arsenic: And the winner is–compost!” about dealing with arsenic in garden soil:

As a gardening novice, I placed a small veggie garden next to an old telephone pole in my backyard. It then dawned on me that maybe the soil could be contaminated with whatever they treated the pole with. The house is 60 years old, so I don’t know, but now I’m tempted to give up, for fear of contaminating my family. Advice?

The stuff we are talking about here is the copper chromate arsenate (CCA) that was used as a wood preservative from the 1930s on. By the 70s it had became the outdoor wood-treatment of choice across the United States until concerns that matched Jen's led to its being banned by the EPA, save for a few rare exceptions, in 2003.

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Compost vs. Arsenic: And the winner is–compost!

Several posts back I mentioned in passing that compost can help fix arsenic in soil, and it seems reasonable to explain what the hell I was on about there. To "fix" arsenic is get it to bond with other, stable molecules so that it can neither leach from the soil into the water supply, nor migrate into your vegetables, and thence into you.

I got onto this originally because the news articles about the great Tennessee coal ash spill of '08 kept mentioning arsenic. Arsenic, I learned, occurs in several different forms, but the one that turns up most commonly in coal ash is arsenate(V), the same form that leaches into soil from telephone poles and fences treated with copper chromate arsenate (CCA).

And yes, at least one recent study conducted at the University of Florida found that when carrots and lettuce are grown in soil that's contaminated by CCA, both vegetables absorbed less arsenic when the soil received plentiful treatments of compost. 

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Er–coal ash as a soil amendment?

I always knew the Brits were crazy.

Given the justifiable panic over the Tennessee fly ash spill here in the States, it’s almost impossible to believe that people might put anything remotely resembling coal by-products in their gardens on purpose, but they do.

Sounds nuts, I know, but experiments have been ongoing in experiments have been conducted in India, Australia, China, and the United States, Poland, Thailand, and who knows, maybe the North Pole, growing vegetables (or in China, trees) in soil amended with bottom ash. Since ash is almost always quite alkaline (pH>9), this only makes sense in soils that have low pHs, but in those it can raise pH, improve water retention, improve mineralization, and increase nutrient availability. And at normal agricultural application rates (20 tons or more (!) or so on each hectare, which is about 2.5 acres) virtually all of experiments I’ve looked at show that these unlikely amendments are not accumulating at dangerous levels in plants.

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