i mix it in when composting, the compost procedure tend to make it break down faster, in soil it'd be useless for probably a good yr or so, but after that it degrades reaaal slow and a consistent source of nitrogen.
I wouldn't topdress with it though, too slow to degrade
I don't recall where i read about the arsenic, let me do some digging on that.
whoa... just looked..
it's allllll over the place.
here's just one link, there are tons of others
http://www.sciencedirect.com/science/article/pii/S0048969711014306
here's a copy and paste from the NY times.
It turns out that arsenic has routinely been fed to poultry (and sometimes hogs) because it reduces infections and makes flesh an appetizing shade of pink. There’s no evidence that such low levels of arsenic harm either chickens or the people eating them, but still...
Big Ag doesn’t advertise the chemicals it stuffs into animals, so the scientists conducting these studies figured out a clever way to detect them. Bird feathers, like human fingernails, accumulate chemicals and drugs that an animal is exposed to. So scientists from Johns Hopkins University
and Arizona State University examined feather meal — a poultry byproduct made of feathers.
One study, just published in a peer-reviewed scientific journal, Environmental Science & Technology, found that feather meal routinely contained a banned class of antibiotics called fluoroquinolones. These antibiotics (such as Cipro),
are illegal in poultry production because they can breed antibiotic-resistant “superbugs” that harm humans. Already, antibiotic-resistant infections kill more Americans annually than AIDS, according to the Infectious Diseases Society of America.
