Answer under construction....

Taking it slowly;

192 tonnes per hectare is 
0.0192 tonnes per square metre (div 10,000)
19.2 kg per square metre over the year 

0.1536 kg per day per square metre (div 125 days)

153.6 grams per day per square metre

6.4 grams per hour per square metre. (Div 24)

0.96 grams of dry matter per hour per square metre (x 0.15)

0.432 grams of carbon per ... ( x 0.45)

Derived from 1.584 grams of CO2 (div 12/44)

Using CO2 level of 410 ppm, 
A cubic metre of air weighing 1.22 kg contains 0.7588 grams of CO2

The averages work out to:
the square metre of beet, per hour uses the CO2 from 2.08 cubic metres of air. (1.584 / 0.7588)

The enzyme RuBisCO captures this CO2.