Assuming some prices lets looks at possible margins over N fertiliser costs:
2021: Wheat £150/t; AN £250/t; BER 5; N rate 200kg N/ha; yield 10t/ha; Margin over N = £1327/ha
2022: Wheat £200/t; AN £600/t; BER 10; N rate 150kg N/ha; yield 9.7t/ha; Margin over N = £1630/ha
2023: Wheat £300/t; AN £1000/t; BER 11; N rate 140kg N/ha; yield 9.5t/ha; Margin over N = £2330/ha
So despite current high N fertiliser price the potential margins are much higher - though of course where grain prices will actually be at harvest 2022 and 2023 is anyone's guess... and other input costs & fixed costs also likely to be higher.
Looking at average yields of 8t/ha and harvest prices:
2021: Wheat £150/t; AN £250/t; BER 5; N rate 180kg N/ha; yield 8t/ha; Margin over N = £1044/ha
2023: Wheat £230/t; AN £980/t; BER 15; N rate 130kg N/ha; yield 7.5 t/ha; Margin over N = £1285/ha
I just edited the first sentence describing the purpose of Farm-PEP to "... to enable knowledge ABOUT FARMING to be ...", just to be clear that we are focussing on farming.
I’ve not looked into the detail, but believe the land use change elements of the specification come from IPCC LULUCF inventory methodology. Data from a review by Dawson & Smith (2006) suggests that conversion from tillage land to grassland can increase soil carbon by between 1.1 and 7 t CO2e/ha/yr which equates to 0.3 - 2 t/ha/yr carbon, but I must admit the 2t/ha/yr seems rather high. At the lower end this would therefore be about 6 t/ha over the 20 year period, which is similar to the 7 t/ha in the standard. So its probably not that far off, and is actually pretty much identical to the lower end of the range reported in the SRUC report at https://farmpep.net/node/246 (Table 5) i.e. arable to grassland anywhere between 0.27 – 1.9 t C/ha/yr (5.4 – 38 t/ha over 20 years).
Dawson, J.J.C. & Smith, P. (2006) Review of carbon loss from soil and its fate in the environment. Final Technical Review Report for Defra project SP08010.
For helpful philosophical points on Regen Ag, see also the articles by Andrew McGuire, agronomist at Washington State University ... links are in a post on the Regn Ag topic
Hi Mukhtar, I think you can find everything you need from the AHDB wep page at https://ahdb.org.uk/knowledge-library/nitrogen-fertiliser-adjustment-calculator-for-cereals-and-oilseeds
I don’t see that Andrew's blog answers his question! Surely the lack of N accumulation in the ecosystem must be because the rate of loss of fixed N (whether biologically fixed or fixed via the Haber-Bosch process) exceeds the rate of fixation. The main N losses from farmed legumes are through their consumption by livestock (which he mentions) but then this is followed by haphazard excretion (which Andrew doesn’t mention) in concentrated patches / regions at rates which exceed plant or crop requirements and then gaseous or aqueous emissions of this N before it can be acquired by growing vegetation. However, many ecosystems do accumulate N, just as they also accumulate carbon.
On 3rd August Innovate-UK-KTN are hosting an applicant briefing webinar from 10am followed by a consortia-building workshop at 12:45pm. More details on this can be found here.