How many tonnes of oxygen are produced per year from each hectare of land growing wheat in UK?
Such figures involve so many approximations that they are bound to be almost worthless! Anything other than wheat grain is converted back to CO2 by respiration of soil organisms which break down stems, leaves, roots etc and this will take up the same amount of O2 as was evolved during its production. So, let’s assume only grain is produced. The record production of wheat is just over 15 tonnes per hectare per annum, but more normally in UK averages about 7 tonnes per hectare per annum. (The record is held by New Zealand, but you will be interested to know that Scotland previously held the record.) Thus, if the straw is left in the field and is eventually broken down to CO2 by bacteria, all that is taken out of the field is the 7-15 tonnes of wheat grain. I have not been able to find a figure for the carbon content of wheat grain, but for every carbon atom in the wheat, on average one molecule of O2 has been produced. The oversimplified formula for photosynthesis is:- 6H2O + 6 CO2 = C6H
