TreeHugger has a look at some lo-tech ways of keeping your garden well supplied with phosphorus (I'm a bit of a skeptic about the "peak phosphorus" idea though) - Homemade Bone Meal: A Partial Solution to Peak Phosphate ?.
A looming peak oil crisis isn't the only thing we have to worry about. Jeremy has already noted that the world could be facing a severe phosphorus shortage over the coming century, a shortage that would seriously curtail our ability to grow food. (Phosphorus is a vital plant nutrient used as fertilizer.) Warren has already pointed out that recycling human urine could help preserve this precious resource, a task that's easy enough for the home gardener. But what other measures can we take at home to keep the phosphrous in our gardens? It turns out that part of the answer may lay in the bones. (The other part may lie in leaving the bones well alone.)
The reason that commercial farmers use bone meal as fertilizer is that it is very high in phosphorous. So purchasing commercially produced bone meal could be argued to be a great way to keep the nutrient cycle going. However, those of us meat eaters who have a problem with factory farming may not be willing to purchase a by-product of the intensive farming industry. So can we make bone meal at home?
Like many other green-minded meat eaters, I try to make the best use of any animal products I can. So usually Sunday's roast chicken becomes Mondays leftovers. The bones from Monday's leftovers become stock for the rest of the week. But what happens to those bones once they are done making stock? Usually I've thrown them out in the trash—but while mulling on the question of phosphorous, I wondered if it's possible to make homemade bone meal.
A quick search of the internet throws up some rare but tantalizing hints that it is indeed possible. A discussion over at freedom gardens suggests burning and crushing your animal bones for fertilizer, or using a solar cooker to dry them, or even just throwing them in the compost pile and hoping for the best. A discussion over at Kitchen Garden throws up similar results for homemade bone meal. Of course, simply burying bones, animal remains or even a placenta and planting a fruit tree over them is an age-old method of recycling. But that's about all I've found, so if anyone else has any suggestions for how to safe, sterile bonemeal, I'd love to hear them.