Miscanthus - carbon sequestration tonnes per ha

[jackrussell101]

Just watched the latest Harry's Farm episode on YouTube, and he said that miscanthus sequests nearly 30t of carbon per ha per annum.

So based on some of these carbon offset exchanges that have sprung up and pay between £30 and £40 a tonne a year of carbon sequested, isn't that nearly £900 a hectare? On top of that the actual miscanthus will come to around a further £900 a hectare from the sale of the crop?

Have I understood this correctly?

If so, it sounds as though growing crops for carbon could be more worthwhile than growing crops for food?

Or will this help lift food prices up?

Or will the carbon broker exchanges drive our sequestration payments down to match margins of food crops?

 

[DRC]

Yes, I think he said 26T ha . Only downside he said was then having to transport it to Lincolnshire rather than his nearest power station at Didcot. It could well be the future

 

[jackrussell101]

Also if carbon offsetting did pay well, does that mean that some farmers doing it may give two fingers to future ELMs, especially if what's on offer is inferior and you've got to employ consultants to get it?

 

[DRC]

Just think, a crop that wouldn’t need red tractor assurance or any inputs once established .
And the ramblers would get lost in it .

 

[AT Aloss]

Miscanthus energy grass



Miscanthus grass is a perennial rhizomatous grass (several species are used) which can average an above ground biomass production of 15 t ha-1 a-1 DM in the UK (King, 2002), and can be harvested annually over a total life-span of about 25 years, giving a total crop of about 360 t ha-1 DM (crop is also cut after first year after planting). For such a crop the amount of carbon sequestered or stored on site was calculated as being 21.9 t ha-1 over 25 years, which incorporated values of 490, 612 & 734 kg ha-1 a-1 C for the soil types of sandy, silty and loam and clay soils respectively as true soil organic carbon at rates akin to reversion to grassland and set-aside (see below), and a standing litter layer of 6 t ha-1 DM and root and rhizome component of about 15 t ha-1 DM (Riche & Christian (2001) measured 13.4 t ha-1), which were considered to be 45 % carbon (the derivation of these values can be found in King, 2002). This gives an accumulation rate of about 0.87 – 1.11 t ha-1 a-1, which has been used here, though the full standing stocks of roots and litter are estimated to be present within four years. This is very similar to the annualised value of 1.22 t ha-1 a-1 measured by Kahle et al., (2002) under Miscanthus plots ranging from 4 to 10 years old, in a sandy loam in north-east Germany (average 15.5 t ha-1 SOM over 4-10 years), but there is generally an absence of direct measurements available from this relatively new crop.



To these figures can also be added a component for the standing shoot biomass which varies from zero after harvest to 6.75 t ha-1 C just before harvest. As it is harvested annually this amounts to a calculated mean value of 3.4 t ha-1 C. Like willow this is included even though all biomass will eventually be burnt and re-cycled to CO2, because if a permanent change in a proportion of agricultural land is made to these crops there will also be a permanent standing biomass carried similar to permanent woodland. Like willow, the above figure is not cumulative and so an annualised increment over the 25 year period has been taken as 0.13 t ha-1 a-1 C.



Miscanthus is also a low input crop that does not require fertilising after initial small amounts of P & K and does not require husbandry operations other than harvesting every year. Therefore similar savings in direct and indirect energy to those under willow can be expected. The overall annualised direct energy expenditure for Miscanthus production has been calculated as being 3 237 MJ ha-1 and indirect energy as 4 220 MJ ha-1 (7 457 MJ ha-1)(Bullard & Metcalfe, 2001) which compares with a similarly calculated total for arable production (Cormack, 2000) of 21 068 MJ ha-1. This represents a saving of 13 611 MJ ha-1 or 275 kg ha-1 C in CO2 emissions.

 

[Flat 10]

But you haven’t fixed the carbon if you then turn round and burn it?

 

[nick...]

I was shocked by the £2000 ha establishment costs and no return for at least 2 years
nick…

 

[delilah]

But you haven’t fixed the carbon if you then turn round and burn it?

As said above....

at rates akin to reversion to grassland

.....its no better or worse than PP. But with rather more burning of fossil fuels in its establishment, harvesting and transportation.
Save the planet: Stick with cows .

 

[jackrussell101]

But you haven’t fixed the carbon if you then turn round and burn it?

Ah I see.

I wonder whether they can invent some way of burning it but then catching the carbon released and pump it underground. I'm sure I've heard of that somewhere.

 

[martian]

Ah I see.

I wonder whether they can invent some way of catching the carbon released and pump it underground. I'm sure I've heard of that somewhere.

Yes, it's called photosynthesis. Plants do it...

 

[GeorgeK]

If permanent pasture was cultivated for miscanthus it might release as much carbon as would be captured over the life of the crop? If you're getting paid to store the carbon what happens when the crop is finished? Can't cultivate or you'll release it...

 

[GeorgeK]

As to how much carbon is stored underground by miscanthus and so allowing for burning the crop it seems like significantly less than 30t/ha/year. Not a UK study but:
"...the underground rhizome and decaying leaf litter fixes and stores net 0.64 tonnes of carbon (2.35 tonnes CO2e) per hectare, each year as it grows."

Terravesta: Miscanthus carbon Miscanthus CO2 Capture Solutions

Terravesta Miscanthus offers innovative solutions for CO2 capture and carbon storage, using Miscanthus plants to absorb carbon emissions and promote sustainability, supporting environmental goals and renewable energy development.

www.terravesta.com

 

[Yale]

I was under the impression that the diversity of species in a cover crop/grazing pasture was the important component in helping to sequester carbon in the soil.

Surely a monoculture of miscanthus creating a sterile environment cannot be good for the soil in which it is planted?

 

[DRC]

For anyone who might be interested

 

[Yale]

For anyone who might be interested

So 3t ish per hectare per year sequestered in the soil also.

Sounds too good to be true…..

Thanks for the link.

 

[Henarar]

Just watched the latest Harry's Farm episode on YouTube, and he said that miscanthus sequests nearly 30t of carbon per ha per annum.

So based on some of these carbon offset exchanges that have sprung up and pay between £30 and £40 a tonne a year of carbon sequested, isn't that nearly £900 a hectare? On top of that the actual miscanthus will come to around a further £900 a hectare from the sale of the crop?

Have I understood this correctly?

If so, it sounds as though growing crops for carbon could be more worthwhile than growing crops for food?

Or will this help lift food prices up?

Or will the carbon broker exchanges drive our sequestration payments down to match margins of food crops?

Sounds just the job for livestock farmers
take the carbon payment, bale it, haul it as far as the yard, put it in the shed and chop it up for bedding in the winter,

 

[GeorgeK]

It seems like it's all about the rhizomes. How much do I get paid for my couch grass?

 

[delilah]

If we put half of the UK down to energy crops (and imported all of the food displaced) how much of the UK's current energy use would we provide ? 5% ?
We could cut the UK's energy use by 5% tomorrow.
Which makes more sense for the environment ?

 

[DaveGrohl]

It seems like it's all about the rhizomes. How much do I get paid for my couch grass?

Fekk that, I was gonna spray buttercups today, not now, they're too valuable it seems.

 

[DaveGrohl]

What does miscanthus do for your drains? Is it less damaging than willow, but still not great?