Biodegradability

What does it mean to say something is biodegradable? Our answer is that if an object is still identifiable after a year in a fairly cool compost bin, it is not biodegradable in any useful sense.

But it is difficult to carry out a comparative trial in a compost bin, so we are trying a substitute approach, putting stuff on the soil surface, covering it with a black plastic bag, and keeping it moist. On 4 July we started with an Ecover bag (A); an M&S potato carton (B and C); a Kanga incontinence pad (D); and an Earthfriendly eco baby wipe (E). More recently we've added a Weenee nappy pad. All the products claim 100% bidegradability/compostability.

The pads seem to be entirely wood-based pulp and tissue, except that the Weenee admits to having some gel ("superabsorbent polymer" - crosslinked polyacrylate). The other items all seem to be made of a polymer derived from starch, poly(lactic acid), or PLA (trade name Ingeo).

So we'll have a look at how they are getting on every couple of months.