We are being encouraged to recycle so many items that the ones that do make their way into the ‘regular’ bin tend to stick in our minds. If you compost or otherwise dispose of organic waste you’ll probably end up with a bin bag full of plastic packaging. If you own a pet cat or dog the warm parcels of their waste will make strange accompaniments to all that inert plastic.
Toxoplasmosis & Toxocara
How can it be that something as natural, green and organic as your cat, can be contributing to landfill in this way? Almost anywhere you look the advice will be to keep your pet waste away from your compost heap despite a growing number of biodegradable litters appearing on the market. The advice is based on the danger of Toxoplasma gondii, a parasitic protozoa (not a virus as is often thought) present in cat faeces. This can cause toxoplasmosis, a potentially fatal disease especially for pregnant women and small children with their still-developing immune systems. Toxocara catis (roundworms) are also likely to be found and can infect humans as well as cats.
Hot compost kills germs
Good reasons to keep cat poo out of your compost then. Well, yes, but there are ways to cope with these pathogens if you know how to compost correctly and with due care. Composts can get to temperatures in excess of 130 C at which point very little living matter can survive. At much lower temperatures in the range of 65-70ËsC, pathogens will still die in a matter of seconds. The British Standard PAS100 ensure that green waste compost reaches 65ËsC for a minimum of 7 days, twice, which is erring on the side of paranoia but they can’t afford to take any risks. What’s amazing is that compost generates these temperatures on its own given the right materials.
Biodegradable litter
With cats, unlike dogs, it’s not just the poo that has to be disposed of but the litter as well. Litter made from clay or silica will not breakdown (in our lifetime anyway) and will get stuck in landfill. There are compostable litters available made from wood chips, sawdust, newspapers and plant derivatives such as wheat or corn residues and wood chips but composting them means removing the poo first, unless you can be sure of getting your compost heap hot enough to kill the germs. This is perhaps ironic as the faeces are rich in nitrogen (which heats the compost) and the litter in carbon (which has a cooling effect) – a match made in heaven from a composting point of view. Remove the nitrogen and the carboniferous material will take an age to disappear. Together they would be much more likely to reach the elusive hot temperatures required to make the compost sanitary. Even if you choose not to try composting the excrement, the litter will have soaked up urine, rich in phosphorus and nitrogen and be a valuable addition.
Cat Poo Wormery
Dog poo wormeries are being found to successfully deal with doggie do but cat poo wormeries aren’t as straightforward because of the amount of litter that accompanies the faeces. The worms seem not to enjoy the quantity or the mix. Removing the poos for the wormery and having a traditional composter for the litter, kept separate from the compost bin you’ll be using for any edibles, might be one solution but if it sounds a palaver having three systems on the go, then read on.
NatureMill composter
One composter that has yet to reach the British market is the NatureMill. Designed by scientist and inventor Russ Cohn, the NatureMill has started to solve the pet poo problems of San Francisco and is spreading across the United States.
The composter automatically grinds the input waste so it acts like a digester where shredding is part of the process. It is normal for digesters to need additional carbon-rich materials such as sawdust or wood pellets to keep the contents at the correct moisture levels and NatureMill is no different. This makes it perfect for the constituents of kitty litter.
NatureMill also maintains an internal temperature of up to 60ËsC (140ËsF) as a small current is used to heat the bin and it is well-insulated. The total electricity used is said to be 5 kWh per month, the same as for a night light. It has a carbon filter to absorb unwanted smells and can be operated indoors or outdoors. The bin costs $299 but a further $82.50 to ship it to Europe, but it really does solve the problem and keep your cat’s waste out of landfill. Compost for the garden is ready in an incredible two weeks. For any cat lovers with no or limited outside space this clever little disposal machine could be the answer. The only problem then is what to do with the compost when the houseplants are well-fed and blooming! How about a spot of guerilla gardening – feed a tree.
Compost alchemy
A fear of germs permeates our culture to the point where stories of sterile homes being responsible for childhood complaints like asthma have spread in the press and the dreadful O.C.D. can lead to compulsive cleaning (not in my house). Yet our understanding of hygiene has saved us from cholera and typhoid epidemics so is there a balance to be aimed for? Perhaps the next stage of understanding germs will come from ecology and knowing how microorganisms interact and keep each others’ populations under control. The compost process is certainly a complex set of interactions of millions of these microbes, their numbers swelling and ebbing according to the conditions in the surrounding environment. And somehow, at the end of it, a clean, sweet smelling earth is produced that feeds our plants and stores potential greenhouse gas carbon in a stable form. Perhaps we can trust Nature after all.
Disclaimer: Composters of cat poo do so at their own risk.
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Sarah Cowell Dip. Hort. is a gardener and writer on horticulture matters
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