[imd321 (OP)]

How much plant material would I need to provide me with sufficient oxygen to breath.  Do all plants produce oxygen at the same rate per kg of material?

[chris]

What an excellent question; I'll need to do some calculating to work this one out...

[CliffordK]

It should be equal to the amount of plant material that you eat....  or if you eat a cow, then the amount of plant material that the cow ate.

[Geezer]

How much plant material would I need to provide me with sufficient oxygen to breath.  Do all plants produce oxygen at the same rate per kg of material?

I think the oxygen production rate varies considerably, and plants both consume and produce oxygen. I've seem some stuff that says an acre of trees will produce enough oxygen to support 18 people, but translating that into vegetation mass could be a bit tricky.

Perhaps you could turn it around a bit and try to determine what would be the mass of vegetation required to absorb the CO2 exhaled by a human and covert it into plant material. I'm not sure, but that might be a more consistent measure, and I suspect it will have a strong correlation with oxygen production.

[CliffordK]

I still think you can consider it to be equivalent to what you eat.

It does simplify things a bit, but consider a vegetarian.

You consume hydrocarbons in the form of plant matter.  This plant matter is converted to Energy + Carbon Dioxide + Water. 

Plants absorb energy from the sun + Carbon Dioxide + Water, and produce hydrocarbons. 

There is excrement, decomposers, and etc.  You also may not eat 100% of the plants.  So, you would have to consider the entire corn plant, not just the corn kernels that you ate.

But, it all comes back to what you have eaten.