I started gardening with only worms to provide manure, but now I live on a cattle farm and obviously there's a big new source to consider. There are about 100 head here, sheltered in a feed lot with a large pasture to roam. With the lawn shrinking and the garden expanding, it's clear that this manure belongs in the mix if I'm going to sheet mulch the universe this year.
Now, the cattle part of the farm is not organic, and I want to be sure I'm doing everything right when it comes to properly handling the stuff. I have read horror stories about antibiotics and pesticides retaining deadly potencies in some manure, but while a harsh chemical disaster is not likely from this cattle manure, I am concerned about keeping my microorganisms safe -- that includes earthworms, bacteria, and fungi. I know the farmer feeds the cattle alfalfa hay first, then corn, then alfalfa to finish; the animals pasture-forage for grass and acorns, too. The corn is probably GM; does this change the quality of the manure? New calves also arrive with some medication in them to buffer the stress of travel and confinement, so I would plan to collect manure before a new load gets dropped off.
Ideally, I would compost the manure outdoors using some passive method so that unwanted residues would be broken down over time, or lose their efficacy in the presence of oxygen-sunlight-fungal activity-beneficial bacteria-etc. But even though my Rodale composting book says to cure and age my cowshit compost, it doesn't say how long this takes or give any specifics that I need.
So to recap: How can I safely use conventional cattle manure or cattle compost in organic and permaculture scenarios? Does the presence of GM corn in the diet of the cattle affect the quality of the manure, or my soil? What is the best method of composting to achieve 'cured and aged' cattle compost? What other tips do you think I would find indispensable? Thanks!
summerstripes wrote: Does the presence of GM corn in the diet of the cattle affect the quality of the manure, or my soil?
the GM nature of the corn itself won't be the issue. after passing through the cows, the genetic material isn't in a form that should be able to cause problems. the real issue will be biocides that were sprayed on any of the feed, whether it's on the corn, on the alfalfa, or on the pasture. several of those can and do survive cows' guts to cause problems in your garden.
asking the farmer what he sprays on the pasture is a good place to start. some expensive lab testing might be the only way to know for sure if the stuff can be cleaned up sufficiently. the USDA organic standards are fairly lax, though. I'm not sure exactly what period of time is required, but manures only need to be aged before they can be applied to organic land, regardless of whether or not the manure came from organic animals. one of the great many problems with the USDA standards.
generally, the more critters and microorganisms that you can get involved, the safer you'll be. sounds like you got an effectively unlimited supply of manure. in your shoes, I might build a big soldier fly larva bin to make food for poultry or fish, then run the larva residue through worms, then age that a bit before putting it in your garden. that would decrease the final volume pretty dramatically and add several steps to the process, but it would also expose nefarious chemicals to a variety of conditions that could break them down, and feed more livestock in the process. soldier fly larvae are pretty tough critters, so they're more likely to handle any fresh nastiness better than worms.
you might decide that that's more trouble than you want to go to, though. and it really might not be, depending on whether the cattle feed actually has any chemical residue on it.
another option would be to compost a batch of manure and see how various plants and soil critters react to it. if they're all sick and dying, you'll know to be concerned. if they're thriving, chances are good you're in the clear.
My personal opinion is that compost with any kind of feces in it should age for at least a year, to break the cycle of any possible parasites.
Technically, a properly managed compost pile can heat up cook and break down the component material in a matter of weeks.
Some pesticides may survive the composting process, so might some antibiotics. Mankind has created thousands and thousands of chemicals and released them into the environment, and we have no idea how long some of them will last.
Composting may be one of the very best methods we have for letting nature fix our sins. Letting a pile sit for a good long time after it cools down allows new bacteria, fungi, earthworms, etc. time to move in and do their business. The longer the compost can age, the better.
Mixing the manure directly into the soil without first composting will allow the toxins to persist in the environment for a much greater length of time.