I contend we need MORE CO2 in the atmosphere than we currently have.
Completely agree, co2 increase will directly increase crop production, regardless of crop! Levels over 1000ppm will promote a vegetation explosion since, as I'm sure you know, carbon from co2 is one of the main building blocks of plants and what it uses to synthesize light into energy during photosynthesis. By increasing co2 plants also require less water, because they don't lose as much water through transpiration.