Cat/dog poo in hugel bed?

Hi all. We have a large bin full of cat and dog poo, mixed with recycled paper-based litter. I understand this should be quite a good mix for composting, which has always been our intention. We are now at the stage where the bin is nearly full (some has been rotting for 2 years) and working out where to spread it.

Our problem is that most of what we grow is edible, and since we are aiming to mimic an early forest we are obviously aiming to have a groundcover/herbaceous layer, which raises problems with contamination from the aforementioned compost.

Would a hugel bed be a suitable way to compost this stuff in place? I'm not experienced with hugel beds (hence asking!) but was wondering if wood piled on top of the compost would do a good job of letting it all break down and not contaminating plants?

Good day Al, This is a great question.

First of all, in a hugel, the manure would probably be packed in with the wood, or on top of it, wood on top won't work well.

Also, it sounds like you have done some research and already know to use the right kind of litter for the cats.

I would be careful using fresh dog/cat poo, especially if you give them de-wormers or any other kind of medication; this kills soil life too!. You will need to compost this stuff hot, and for a good while in order to kill those.

Otherwise, the best advice I can give is to dilute that stuff with other sources. Too much of one thing is never good. Dog poo, for example can be very high in phosphorus.


If I were you I would compost that stuff, covered with a black tarp, with about equal parts of saw dust, 1.5x parts wood chips, or 3-4x parts leaf mulch. You will need to be sure you keep your animals from "reclaiming" any of these nutrients, as this can increase the likelihood of parasite infection, such as roundworm and flatworms.

I personally scatter the cat waste in a non food bed, under mulch, where my dog cannot get to it, and I wash the dog poo into the ground with water and a rake.

Thanks, Hamilton - that's a really useful reply. Will most likely remove the bottom layers (well rotted) and use as compost for flower/insectory bed, and follow your advice on mixing the rest with other materials to balance it out.

What is the rough composition of the manure, you mentioned phosphorous; is it high in nitrogen too? (I think I recall this is why balancing out with carbon-heavy paper littler is good).

Hi Al.

I feel the need to stress the pathogenicity of cat feces. It is not the same as even the feces of omnivores. That shit is bad.

You can use it, but as Hamilton mentioned, it needs special treatment. I don't think it necessarily needs to be sequestered from the ground environment when hot-composting, but I would be careful that the pile has enough moisture at all times without there being so much that it's in danger of leaching into the surrounding soil, uncomposted.

The method I would use, if I were to tackle that problem in my urban backyard, would be to get a large, black tarp in the sun, pile all that shit on there, cover it with another large black tarp, and let it cook until there's no moisture left. Black metal buckets in the sun would work, too.

I especially like a setup where a black receptacle can be placed in a sunny spot to be constantly heated, with ventilation appropriate for such a task (a chimney to take the smell well above the affected area), and perhaps a larger black metal heat intake to raise the temperature of the incoming air. Such an installation in a public dog park, on the south face of a lamp post, for instance, could do a great job of cooking fresh dog feces to dry powder. The resultant poo powder would be sterile, and could safely be dropped in a compost with sufficient carbon, or atop wood within a hugelbeet, for instance. The issue of excess macronutrients is still of concern, but at least you won't need to pyrolise your hugelbeet due to excessive soil pathogenicity. Or worse, toxoplasmosis.

I would be less worried about dewormers, but it is a strong argument for a separate disposal process. If your pets are unmedicated, go for it, as soon as you've dealt with the pathogen issue. If you medicate your pets, I would solarise their contributions, and then dilute with fresh compost and mulch, apply around ornamentals, and top with more mulch and a monthly fungal slurry, preferably oyster or winecap. The fungi should sequester and/or break down residual medications as well as other pollutants and contaminants.

And if this sounds excessive, I would take the same sort of approach with feces from a medicated human. That shit's going in a mixed bacterial/fungal compost, and in an actively aerated bioreactor setup if I can manage it, and then out to an expressly non-edible area of a shelter belt woodlot as fertigation. I can chop-and-drop undergrowth intended for that purpose and the fungal breakdown will continue, and I can make biochar with the trees that sequester contaminants in a pyrolising woodstove or rocket mass heater.

At that point, I would consider the biochar a good addition to the hugelbeet.

-CK

Al William wrote:Thanks, Hamilton - that's a really useful reply. Will most likely remove the bottom layers (well rotted) and use as compost for flower/insectory bed, and follow your advice on mixing the rest with other materials to balance it out.

What is the rough composition of the manure, you mentioned phosphorous; is it high in nitrogen too? (I think I recall this is why balancing out with carbon-heavy paper littler is good).

The composition of the poo is dependent on the their diet. But yes, typically poo is high N too.

The USDA has a pretty good guide for doing this safely; although they are probably not the best bastion of knowledge.

https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_035763.pdf

Hamilton has done a good job of covering the concerns of pet manures, including how to make good use of it.

I always compost pet manures in a hot heap, rotted or not, pathogen possibilities are still there unless you have heated it to above 160 f.