Category Archives: WILT, or What I Learned Today

Ashes: Almost the Perfect Lawn Amendment

The Soil Series # 3

Having gone on at some length a while ago (twice!) about how wood ashes aren’t going to cause lead or mercury or cadmium poisoning if you use them in your garden, I am now prepared to tout them as the nearly-perfect lawn fertilizer. Since it seems that I’ve adopted this poor, misunderstood amendment as my own, I might as well do it thoroughly.

Grass needs calcium, which might be considered a non-renewable resource in a lawn: once the roots have used it up, it’s gone. So additions are necessary. The most common materials for such additions are gypsum, which contains about 22% calcium, and lime, at about 30%. The calcium content of ashes varies widely depending on type of wood, but even softwoods will produce ashes containing about 15% calcium, and hardwood ash may be as high as 50%.

A couple of things make ash a superior amendment, especially for lawns. For one thing, both gypsum and lime are quite insoluble. The term “immobile” seems an excellent metaphor for how they behave when applied to grass, but it’s also the technical term for a compound that doesn’t dissolve easily and therefore doesn’t move with water into and through soil. As a result, it is hard to get lime and gypsum into a plant: unless they’re snugged right up against the roots, they might as well be on Mars, for all the good they’ll do.

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WHY Decomposition Uses Nitrogen (or, What I Learned Today #2)

A couple of weeks ago I wrote about what happens when sawdust decomposes. But the account was incomplete, and I am here today to rectify that error. Call me honest, call me obsessive; I’m going to set the record straight, sawdust-wise.

I wrote then that sawdust makes a lousy lawn fertilizer because it requires so much nitrogen to decompose, and it contains very little. So far, so good. But when I wrote that “it requires nitrogen to break down, and it’ll make use of whatever it can lay its sawdusty little paws on,” I misspoke.

I know what you’re thinking: sawdust does not have paws. But that’s not where I’m headed. No, what’s at stake here is not anatomy, but agency. It’s a mistake to refer to sawdust as making use of nitrogen or to suggest that sawdust “gets” nitrogen whether with paws, hands, or any other part of its being.

It’s a mistake, in a sense, even to refer to sawdust (or anything else) as decomposing, as if this were something that it did all by itself. In fact, of course, something decomposes it. And not just one something; lots of somethings. These somethings are called—brace yourself—decomposers.

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The Worst Amendment for Lawns: Sawdust. (Or, What I Learned Today #1)

Refusing to be scared off by unfortunate acronyms, I’m starting a whole series of posts to be titled What I Learned Today. This is the first.

As you can see from the #1 in the title.

Though I could have put that there just to confuse you.

But I didn’t.

I’m beginning to sound like Esther. Or Winnie the Pooh. Yippi!

Down to business:

A couple of years ago I read that sawdust was the last thing you wanted to sprinkle on your lawn (unless you liked that sickly yellow color), but I’d completely forgotten why. This did not keep me up at night until recently, when I was working on the soil amendments part of my endless organic lawn care article (I’m up to page 112, and counting), and wanted to say something intelligent about sawdust as an amendment.*

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A Lighter take on Heavy Metals

Given that my "Heavy Metals in Wood Ash" post appears to have gone over like a lead balloon (yuk, yuk), I thought I’d try a shorter version and see if that flies.

To start at the end: a fair amount of research has been done, all of it concluding that it is safe to use wood ashes in gardens in moderation. The ashes contain only trace amounts of heavy metals, and the metals do not move into whatever is grown in them. And yet, on-line question and answer gardening sites often do not mentioned this research or its conclusions.

That makes me mad. I expect people handing out advice to know their stuff. Silly me.

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