- Location
- Exeter, Devon
That’s an awful lot of 000’s!I am not arguing against using N fertiliser, I can't farm profitably without it in todays markets! I am arguing that at present, farming and forestry doesn't even have the capacity to off-set the carbon being released every day globally, through deforestation and soil degradation, let along to think we can somehow soak up the carbon being released from pre-historic carbon sinks!!
if our unfertilised crop captures 1 unit of carbon and after a year or 2 it has all been released again the next effect on atmospheric CO2 is, in reality, zero
if our fertilised crop captures twice as much carbon again after a year or 2 it has all been released the next effect on atmospheric CO2 is again zero
ever if our fertilised crop sequesters 1000 times more carbon if after a year or 2 it has all been released the next effect on atmospheric CO2 is still zero. Crop biomass is simply not a true carbon sink when ultimately every crop or tree we grow is consumed and its nutrients released and recycled, be that in a week, a year or 100 years.
it is worse than that though because there is also the carbon cost for creating and applying N to the fertilised crop
if producing our fertiliser releases 1 unit of carbon from fossil fuel and our fertilised growing crop captures, but ultimately releases again, 100 units of carbon, the net effect on atmospheric carbon is not a reduction but an addition of 1 unit... and another next year and another the year after....
Biomass, fertilised or otherwise is not a carbon solution if it only results in transient carbon fixation.
Yes absolutely agree there is utterly no point in us planting a few trees, even a few billion trees, whilst global deforestation runs riot. If the UK started tree planting today at a rate to match deforestation we would have planted every acre of farmland in this country as early as March next year! Now take that and ponder this for a moment, the CO2 released from fossil fuels each year is said to be at least 10 times greater than what is released though global deforestation....
Trees take time to grow and sequester carbon so lets assume we decide to plant a carbon soak up forest over the next 5 years...
- a forest that can soak up all the CO2 we expect to release from fossil fuels for the next 50 years
- lets assume fossil fuel usage over the next 50 years remains the same or at least averages no more than todays figure releasing 35bn tonnes of CO2/year
- lets assume we can grown a mature forests to a 250t/ha of biomass during those 50 years...
- lets assume CO2 is by mass 33% carbon and forest biomass is 50% carbon
How many trees do we need to plant to soak up the next 50 years of fossil fuel carbon?
35,000,000,000t CO2 x 50 years = 1,750,000,000,000t of CO2 to sequester in biomass.
x0.33 = 577,500,000,000t of carbon to sequester in biomass
x2 = 1,155,000,000,000t of biomass
/250t per ha = 4,620 million Ha of forest!!
So even ignoring further deforestation, in order to offset the carbon we might reasonably expect to be released from fossil fuels over the next 50 years it would require the immediate planting of a forest that is more than 240 times larger than the total farmed area of the UK!!
There is a mistake in there somewhere, I hope!