Don't stop the Rot

Imagine dragon flies with close to a metre wing span hovering around in huge swamps full of lush vegetation. The carboniferous period, where massive amounts of atmospheric CO2 was locked up by forests made of newly evolved lignocelluloses (wood). These left us the coal seams we have today, as they could not be broken down. Then about 295 million years ago, an adaptation in a group of fungi allowed for the breakdown of lignocelluloses. This group of fungi became known as the Agarimycetes. They can be divided into two groups, white rot and brown rot fungi. These fungi specialize in turning wood back into carbon to start the carbon cycle again. Composting toilets require additional carbon to add to the nutrients in our byproduct (such as Nitrogen and Phosphorus). To successfully make compost, a ratio of about 30 parts carbon to 1 part nitrogen must be adhered to. We add this by sprinkling a cupful or so of dry wood shavings, sawdust, dry leaves, rice husks…etc over the last deposit of humanure. This allows the moisture in the toilet to be absorbed and made available for micro-organisms and fungi to live. Just the right amount of moisture will promote the growth of one of the Agarimycetes and start to breakdown the wood into carbon for the Nitrogen to bond with and turn into compost. Some compost toilet aficionados may have noticed that when using pine shavings, not a lot of breakdown of wood occurs inside the chamber. I have noticed this often when servicing units for clients. Pine shavings are easy to source and sustainable as they are from plantations. Most major brands recommend using them. However, I have rarely seen the expected fibres of fungal hyphae running through it to break down that carbon. To find out why this may be so, I have had to investigate the types of fungal rot that might be required. Most brown rot fungi are generalists or gymnosperm (pine) specialists, whereas most white rot fungi are angiosperm (flowering plants) specialists. It may very well be the case that the most prevalent fungal species we have in our region are white rot fungi, i.e. not very good at breaking down pine. Having said that, we do have some native pines and one would expect the fungal spores to be present if not ubiquitous. My advice to those that want quality compost is to source your bulking agent from locally sawn hardwood, such as the mill at Kyogle (or any timber mill) where a trailer load is still only $20. Use a piece of rotting hardwood from a wet forest somewhere near you and throw this into your toilet to inoculate it with the correct type of rot. If you wish to pursue the softwood option then perhaps experiment the same way with some rotting pine from a plantation.