Justin Newcombe debates the finer points of nature's pungent fertiliser.

An endangered faeces artwork, made from Zoo Doo - manure from animals at Auckland Zoo. Photo / Supplied

Before I get to into this delicate topic, I want to say right at the top there's always slow release fertiliser if you don't want to read on, but where is the fun in that?

A lot of gardening culture revolves around best kept secrets and one of my best kept secrets was my secret poo stash on Mt Eden - cow poo that is.

Two years ago the council and the gang decided grazing cattle on Mt Eden was inappropriate and my urban dung supply was abruptly cut. Since the great poo drought began, we've been keeping poultry so our domestic poo supply is thankfully secured. Actually, I would say the poo is more valuable than the eggs, especially since the sulky little strumpets have gone off the lay.

The difference between cow dung and chook poo is actually quite considerable. In a manure context, of course, cow dung is high in nitrogen and a lactating cow is one of the highest producers of nitrogen in the animal kingdom. A chook however is better. As well as nitrogen, cows and chooks also produce good amounts of potassium. The advantage cow dung has over chook poo though is the volume (obviously), but also the texture of the good old cow pat. A semi-dry pat is a great soil conditioner and compost activator. While chook poo is markedly more potent, it clearly lacks this volume.

Horse manure is another popular, choice with a farm horse heading off a race for dung quality. Even though horse manure is inferior to both chook and cow poo when it comes to potency, it is texturally superior and in my opinion has a more considerate aroma. A horse also spends a lot more time inside where its manure is often conveniently mixed with straw making it an excellent addition to any heavy soils.

Another poo high on the popularity stakes is that from sheep. This is the most convenient type of poo because you can buy it already in pellets from Bunnings. However, there's nothing like spending an afternoon with bucket and shovel collecting nature's freshness. It's also the right size and consistency for throwing, although I have also had a bit of success using a dry cow pat as a poo frisbee.

A quick word here about poo safety. Firstly, wear gloves or at least wash your hands before you have morning tea. Secondly, a lot of animals are given many drugs, the residues of which are often present in their faeces. These include battery hens, race horses and pigs, so collect your poo from a garden-friendly source.

Zoo Doo, manure from zoo animals, of course takes the cake for its "endangered faeces" artworks, with the added social advantage of providing work for people with a psychiatric disability. But from the more plebeian poos available, the Academy Award for volume per body weight, nutrient value, stickiness, coverage of an otherwise idyllic setting, general unpleasantness - in other words best poo around - goes to the humble duck. Who would have thought?

By Justin Newcombe Email Justin