I saw a lot of good money spent on "biodegradable" cups, plates and trash bags this past week.
For those of you who've never had a tour of a landfill, nothing rots in a modern landfill.
Modern landfills permanently entomb trash within impermeable layers of rock and plastic sheeting (see pic.), compacting the refuse into a dense, anoxic environment that prevents the infiltration of water or air (and therefore any real amount of biological decomposition). This is a good thing! The last thing you want is for a city's worth of old batteries and diapers to corrode and seep into the groundwater. Completed landfills are sometimes covered in grass and converted to golf courses or parks, but trees can never be planted due to the disruptive impact of their deep roots.
I find the biodegradable sales pitch especially disingenuous when it comes to "compostable" plastic products made from corn. These plastics are only compostable under rigorous, professional conditions. If you throw them in any old pile, they'll be around for years just like corn cobs or wood.*
I don't see cutting down on landfill space as a big environmental priority at any rate (especially in a country with as much surplus wastelands as the U.S.). I'm a lot more concerned about slowing the paving over of our best wildlands and agricultural soil, and conservation that limits the oil and mining-intensive production side of consumption (as opposed to just figuring out how to throw out what we're done with).
Use it up, wear it out, fix it up or do without...
* Has anyone actually tried to compost these corn plastics? Did it work? What are your conditions?