Source: Bloody Brilliant!
It's spring, time to dig in the composts and pile on the mulches, so the blogging world is full of advice and debates about manure. Stuart of Gardening Tips and Ideas has just weighed in on the side of sheep manure, while Elizabeth and Michelle of Garden Rant defend manure against all comers.
Me, I can hardly bear to think about the stuff. The minute I hear the word “manure” I start to twitch and moan; observers report having heard mutterings of “No, no,” and “Tell me it isn't true.” I wanted to post on this topic (the manure, not the moans) weeks ago, but after the incident with the broken blood-pressure cuff, my doctors warned me not to write about it for at least a month.
It's all about the stuff they add to animal feed. I stumbled over it when researching the compost article (how else?) and haven't entirely recovered. Here's what happened.
We all know (I assume) about the antibiotics and hormones in manure, but I got more and more curious about repeated mention of heavy metals and salts. It's such a prevalent problem that farmers hesitate to use manure as a fertilizer, and gardeners are warned not to use heavy treatments year after year.
What are these things doing in manure? I wondered. How'd they get there? Was it always so? (How could it always have been so?) Well, no, as it turns out, it wasn't always so, but it is now, and as is so frequently the case, there are many routes and causes. There's whatever was used to treat the wood of the barn or shed, which chips off and gets mixed in with bedding, which gets composted with the manure. There's the stuff put on animal hoofs to keep them from cracking—it contains copper. (I'll bet anything that this is more necessary in crowded feedlots and with animals that spend their lives on cement floors than with pasture animals.)
And then there's my favorite, the source of all those twitches and moans: animal feed. Animal feed contains heavy metals. But—and here's where it gets downright funny: they're not a contaminant, they're additives. They're put in there on purpose! Yes, it's true—we put heavy metals into the feed for our pigs and chickens and steers and turkeys and sheep. (We're a bit more careful when it comes to laying hens and dairy cows.)
Arsenic, for instance. In many parts of the country, poultry raised for meat are fed arsenic compounds as an appetite booster—you want these babies to gain all the weight they can, after all, not just to eat what they need. Regulations—about whether or how much arsenic can be included in poultry feed, about acceptable arsenic levels in compost, or in soil—all these vary by state, and they vary hugely.
In Prairie Grove, Arkansas, poultry litter was regularly used as a fertilizer by poultry farmers. The dust at application time drifted into homes and schools. Then people started to fall ill with rare cancers, including leukemia, and brain and testicular cancer. A number of people, including four children, have died. Many more are ill—and all this in a town of 2,500. Numerous lawsuits have been filed, and are wending their ways through the courts.
Pig feed contains copper compounds for the same reason. One recent German study found that cattle farmyard manure contained 25 mg/kg of copper, but pig farmyard manure contained over 200 mg/kg —more than eight times as much. Pig slurry, however, was as high as 530, and slurry from young pigs more than twice that again. Then there's the zinc, which is also incredibly high in pig slurries.
As for the salts, this is not quite clear. Many of the metals are also, technically speaking, salts, but whether the warnings about salt buildups in soil refers to these or to more ordinary table-salt salts (sodium chloride and closely related chemicals) I'm not yet sure. (If you know, tell me!) Mammals do excrete salt to some extent in feces and even moreso in urine, which is often mixed with feces to create manure. So the salts are at least in part “natural,” though I've certainly seen several references saying that manure from feedlot cattle contains higher levels of salts than that from, say, dairy cattle.
Now, I understand the “need” to feed healthy animals antimicrobials and hormones; after all, we keep them in such crowded, unhealthy environments that without the drugs, they'd be dropping like flies. And since speed is everything, the antibiotics and hormones that increase weight gain are as American as apple pie. (Of course, there's the slight problem that we can't export meat to the EU, where both hormones and non-therapeutic antibiotics have been banned for years, but oh well.)
Ditto with the tranquilizers fed animals in feedlots; after all, you'd panic too, if you'd been shipped to this insanely crowded place after spending your life in a stall not much bigger than your body. So by all means, pour on the hydroxyzine, reserpine, and trifluomeprazine.
But I draw the line at the metals, especially when they're added to feed in such quantities that the manure is too toxic to apply to farmland. Not to mention, so toxic that if people breathe the dust, they get cancer.
Tell me: why do we poison our food?
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