I don’t understand how 130kg can contain 145kg… Are there different laws for atmosphere weight compared to sea-level weight. Or are my numbers wrong?
When carbon burns, it reacts with oxygen in the atmosphere:
C + O2 -> CO2
So the 145 kg of CO2 come from the carbon in the straw and the oxygen in the atmosphere: 12 g of carbon react with 32 g of oxygen, producing 44 g of CO2.
Edit: The molecular weight of carbon is 12 as much as hydrogen, oxygen 16. That’s how I got those numbers.
Your numbers must be wrong. If I had to guess, you were using a chart of biomass for the wheat plant, which includes straw, seed that people harvest and make into bread, and roots, which stay in the soil.
From that perspective, it is sounds realistic that a certain number of wheat plants consumes 145kg of CO2 during their lifespans, and yields 130 KG of straw (plus roots and wheat). The root mass of most plants is approximately equal to above ground mass, and about half of the dry biomass comes from water (hydrogen incorporated into carbohydrates like cellulose), and half from air- plus a tiny amount from soil minerals.
Carbon has a molecular weight of 12. Oxygen has a molecular weight of 16. The carbon is in your hay and will pull in oxygen from the atmosphere to make CO2 which has a molecular weight of 44.
Not all your hay is carbon but this is why the CO2 weight is higher
Tl:Dr; for the rest of the entries: the hay sucks in additional mass from the atmosphere, bundles it with it’s existing mass, then expels out the toxic combo-mass
A CO2 molecule contains one carbon atom and two oxygens, and is 73% oxygen by mass. The oxygen doesn’t come from the hay bale, but from atmospheric O2 when the hay burns.