As far as the oxalis corms (aren't they actually tubers?), burying them deep for an extended period will indeed get rid of them. You could also dig a very deep hole with a pair of post hole diggers and then toss all of them in there together rather than trying to bury the whole area.

I mulch all of my pathways yearly with layers of newspaper just as you are doing on your beet bed. I top the whole thing off with a big layer of hay (4 or 5 inches) and that mulch lasts me the better part of an entire year.

I don't add any sort of nitrogen to speed decomposition because that would defeat my purpose.

Hm. After a bit more research, they aren't corms OR tubers. They're spread by rhizomes and bulbs. Dratted things.

The decomposition question is affected by the fact that in CA we don't get rain for about 8 months, so oxalis isn't that big of a deal in summer. Maybe. So maybe I want that mulch to break down and add OG? Also, if I add another foot of soil did I want to use the newspaper/leaves as oxalis barrier or as decomposing OG? Because as I understand it leaves take about two years to break down on their own.

Could be wrong. Have been before (see above!). Dunno...this is just information gathering until we get down to the nitty gritty of spring cleanup. Hmmmm. Hmmmmmm.

How long it takes depends on your soil. A soil with a good active Soil Food Web will see the newspaper and leaves digested in 1 year while a soil that does not have that could see them last several years.

Moisture is an important part of the decomposition process, too, so if you want to speed it up, be sure to add some if it doesn't come naturally.

Thanks! Will have to ponder this.

I would guestimate that after one year - you might still be able to find recognizable bits of newspaper but most of it will be crumbly and broken down.

If your intent is to kill the underlying weeds, you may not want the stuff to break down too quickly.