Some companies are offering plastic forks and spoons that they claim will decompose in a compost pile. First understand that the conditions in a landfill is not the same as a compost pile at all. A landfill is an anaerobic environment where things just don’t break down chemically. A compost pile is turned at least every other day to keep oxygen flowing to the microbes to they can do their job, so it’s an aerobic environment. But a compost pile also needs care every week to make sure it doesn’t dry out. If it dries out too much, the microbes die and items are not chemically broken down.
So I decided to do my own experiment. We bought some “compostable” plasticware and on May 1, 2019 I put it outside in contact with the ground, so microbes would be able to access it, and covered it with a mesh bucket with a brick on top, so insects could get to it, but larger animals could not carry it away. Also I wanted the rain full access to it.
I checked it on March 12, 2020 and the plastic fork I put out there, which had gone through a full summer and nearly full winter, was completely unchanged physically and chemically. Though it did have a little dirt on it, probably from splashing rain.
So don’t waste your money on these, they don’t work in real world conditions.
Update September 2020. “Compostable” plasticware is completely unchanged and is only slightly dirty. There is no sign at all of physical degradation.
