While I won't personally recommend feeding chickens soil fertilizers/amendments, what I will suggest and is something that I do, and it's one of the ingredients in the soil amendment found in the link you provided. I give my chickens kelp, mixed into their layer feed. Kelp has a wide array of minerals found in the periodic table of elements, often with super stout levels of iodine, and these minerals found in kelp are biologically available for chickens (and people too) to absorb and be assimilated by the body. It's one great way to help ensure your chickens get a more mineral rich diet.
Another route to add minerals to a chickens diet (and here again, people too) is offer them unrefined sea salt. The unrefined sea salts have color, often a sort of light grey or brown color to them, and is a great visual indicator that all the other minerals present in the sea water that was evaporated to make that sea salt are present in the salt crystals. Sea salts that are snow white in color tend to be missing the naturally occurring levels of sea minerals. Sea salt can be offered to them in a separate container and they will peck and eat it as they so desire. As a side note, I put sea salt my water I drink every day. I don't add so much that it tastes salty or like ocean water, just a little pinch and the flavor is hardly noticeable, but I'm giving my body low doses of a large number of minerals found on the periodic table.
Hope this helps!
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
I would not offer them soil amendments. Too much of anything can be bad and cause health problems, and in the case of soil amendments even if the minerals themselves didn't cause damage I would worry it could contain lead or other chemicals/contaminates (regardless of what the label says, the amendments are not tested for human or animal consumption).
Even the calcium in layer pellets can cause organ damage if the birds are not currently laying so I feed my mixed flock game bird feed and offer oyster shell on the side for the layers that need it (since the roosters, chicks, and older non-laying hens do not need extra calcium).
The article recommended soybean, canola, and cotton seed meal as garden amendments. Not sure about cotton seed but soymeal and canola meal are very commonly included in poultry feeds as a protein source. In garden soil feather meal would be a slow release source of nitrogen. Feather is mostly composed of keratin, a protein, it could be fed to chickens.
Too much fish meal fed to chickens makes the eggs and meat smell and taste fishy, in limited amounts it is a source of protein. If you do not mind the taste in your eggs it would be worth experimenting with if the price is right. It would be a source of nitrogen and trace minerals for garden soil.
Phosphorus and calcium need to be kept in the proper balance in living animals. Rock phosphate is a source of phosphorus. Gypsum is a source of calcium. Bone meal is a source for both. I don't know how well a chicken can utilize any of these sources. You could try it if you want. Assuming you have layers, watch the shell thickness and texture. If you have problems then you have problems with the calcium levels biologically available to your chickens.
Kelp and azomite would be good to offer for trace minerals.
Chickens will eat what they need as long as it is available. If their manure never leaves your yard than the minerals will slowly be cycled into your soil.
Leora Laforge wrote:The article recommended soybean, canola, and cotton seed meal as garden amendments. Not sure about cotton seed but soymeal and canola meal are very commonly included in poultry feeds as a protein source. In garden soil feather meal would be a slow release source of nitrogen. Feather is mostly composed of keratin, a protein, it could be fed to chickens. .
I bought a 50 lb bag of soybean meal at the feed store, It is 49% protein so I thought it would make an emergency food source for the dogs/chickens and me. The stuff was horrid, I tried it and hated it, the chickens didn't like it, and I didn't feel right about feeding any of it to my dogs.
I looked up whether it could be used as fertilizer since I didn't know what to do with the bag, turns out it has an n-p-k ratio of about 8-1-2 makes a great slow release fertilizer. Easy to apply and a little goes a long way!
You guys are all great! I'm making an Amendment Caddy, that will contain their oyster shell, kelp meal, sea salt, grit from two different mineral sources (if I can find it), and I'll cautiously try a bit of gypsum and rock phosphate if I can find them in non-powder form. I love all your ideas - permies.com is the BEST!
permaculture is largely about replacing oil with people. And one tiny ad: