Scottish Nitrogen Balance Sheet 2022
The Scottish Nitrogen Balance Sheet brings together evidence on flows of nitrogen in Scotland from across the whole economy to understand and keep track of the use of nitrogen.
Table 9. There have been broadly no major changes to NUE values calculated for previous years.
Comparison between the NUE values for 2021 in last year’s release and this year’s release.
|
NUE Groups |
Input Previously |
Useful Output Previously |
Efficiency Previously |
Input Revised |
Useful Output revised |
Efficiency revised |
|
Arable |
86.7 |
56.1 |
65% |
86.7 |
56.1 |
65% |
|
Livestock |
197.2 |
19.7 |
10% |
197.2 |
19.7 |
10% |
|
Whole Agriculture |
183.8 |
51.5 |
28% |
186.9 |
51.5 |
28% |
|
Aquaculture |
21.2 |
7.4 |
35% |
21.2 |
7.4 |
35% |
|
All Food |
205.0 |
59.0 |
29% |
208.1 |
59.0 |
28% |
|
Forestry |
27.3 |
8.2 |
30% |
27.2 |
8.2 |
30% |
|
Whole Economy |
296.0 |
75.1 |
25% |
279.0 |
67.2 |
24% |
Revisions made to SNBS methodology
There were two changes to source data used.
Data relating to the production, trade and some use of fossil fuels was previously taken from the Scottish Energy Statistics Hub dashboard. Over the course of the previous release and this release we have transitioned from using the data from this dashboard to using data directly from the sources to this dashboard. This has resulted in few changes, primarily due to the fact that revisions in the source data for fossil fuel use will now result in changes in the SNBS as that source data is published as a time series.
Data from SEPA on business waste is now being drawn from SEPA’s dashboard for data instead of the previously used spreadsheets that SEPA published in the past. This has the advantage of the data on SEPA’s dashboard being available in a time-series format where the spreadsheets were single year snapshots, meaning that SEPA’s revisions to their data will now result in changes to the relevant SNBS data.
This SEPA dashboard also contains non-business waste data (households and construction). Previously data for this was obtained by subtracting the business waste data from the total waste data, however using SEPA dashboard this is now obtained directly and has the same advantages with regards SEPA’s revisions being able to propagate through that there are with the change to business waste.
Last year we added international trade in food and drink (trade outwith the UK) based on HMRC customs data, however due to the nature of customs data this could not reflect the much larger trade in food and drink with the rest of the UK.
Flows relating to trade with the rest of the UK in food and drink have been added this year based on the Scottish Supply, Use and Input-Output Tables, however these flows are only available up to 2021 due to these tables being published in greater lag than the SNBS. Additionally, due to these tables being based on the value of goods rather than the mass of the goods we have been forced to make the assumption that the price per kilogramme of goods traded with the rest of the UK is similar to that of goods traded internationally.
A flow has been added based on the NAEI Air Pollutant Inventory on waste from road tyre wear. Most tyres are made from synthetic rubber and so, as with all other plastics, contain Nitrogen. This release of micro-particles from tyres would represent a flow of NItrogen from the manufactured world into the natural environment.
Removal of imports and exports from NUE calculations
Following discussions with experts from UK CEH, changes have been made to the NUE calculations with regards the inclusion of flows relating to imports and exports.
Part of the purpose of the NUE calculations is to reflect the Nitrogen cycle, the cycle by which Nitrogen is converted into multiple forms as it circulates through the environment and economy, and the extent to which Nitrogen is not lost from this cycle as waste.
Imports and exports represent “inert” forms of Nitrogen, when Nitrogen is imported as food it does not change form as part of this process. This is in contrast to the other flows which more properly form part of the NUE calculations where the Nitrogen does change form and so can be said to be “reactive”. An example of such flows are the flows involving “reactive” Nitrogen are those relating to combustion where Nitrogen changes form from being locked up as fuel to change into waste gasses (the greenhouse gas Nitrous Oxide or the air pollutants Ammonia and Nitrogen Oxides).
Including imports and exports artificially inflates the efficiency of the economy. It is important to remember that much of the Nitrogen that would be exported is already counted as part of the harvest from the agricultural sector, which does represent the Nitrogen materially changing form from living animal or plant to food.
The most up-to-date data source at time of assembly is used for the SNBS. Wherever the source dataset includes revisions these will be propagated to the SNBS flows. Some of the flows which have seen the largest changes as a result of this include:
- “Livestock excreta for use in anaerobic digestion” and organic fertilizer flows which are based on agricultural emissions data
- “Feed from in-farm production” which is based on crop area data from the June Agricultural Census
- Various changes to atmospheric flows based on the NAEI’s GHG and API data.
- “Fossil fuel for use in Transport (road)” which reflects an increase in fuel consumption due to methodological changes in DESNZ’s sub-national road transport fuel consumption statistics publication
- “Fossil fuels for use in Transport (aviation)” which changed by ~13% in 2021, which is based on the NAEI’s GHG data.
- “Fossil fuels for industrial uses (combustion)” due to an increase in the estimated use of coal in DESNZ’s subnational total final energy consumption publication.
- Various waste flows due to revisions in the SEPA source data