Scottish Nitrogen Balance Sheet, 2021
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. The whole economy NUE is unchanged, remaining around 25%
Comparison between the NUE values for 2019 in the initial SNBS and the values for 2019 in this year’s release. Inputs and outputs in kt N /yr.
|
NUE Groups |
Input Previously |
Useful Output Previously |
Efficiency Previously |
Input Revised |
Useful Output revised |
Efficiency revised |
|
Arable |
90.2 |
58.2 |
65% |
91.7 |
58.0 |
63% |
|
Livestock |
198.7 |
19.6 |
10% |
198.7 |
20.1 |
10% |
|
Whole Agriculture |
200.1 |
54.5 |
27% |
197.8 |
55.0 |
28% |
|
Aquaculture |
21.3 |
7.3 |
34% |
21.2 |
7.3 |
35% |
|
All Food |
221.4 |
61.8 |
28% |
219.0 |
62.3 |
28% |
|
Forestry |
28.2 |
7.5 |
27% |
28.2 |
7.5 |
27% |
|
Whole Economy |
308.2 |
77.7 |
25% |
317.5 |
78.2 |
25% |
Table 10. The whole economy NUE for 2020 is slightly lower using the latest available figures, being around 26% where before it was 27%.
Comparison between the NUE values for 2020 in the last year’s SNBS and the values for 2020 in this year’s release. Inputs and outputs in kt N /yr.
|
NUE Groups |
Input Previously |
Useful Output Previously |
Efficiency Previously |
Input Revised |
Useful Output revised |
Efficiency revised |
|
Arable |
93.1 |
58.2 |
62% |
88.9 |
58.2 |
65% |
|
Livestock |
197.3 |
20.0 |
10% |
197.3 |
20.0 |
10% |
|
Whole Agriculture |
187.7 |
55.4 |
30% |
185.0 |
55.4 |
30% |
|
Aquaculture |
23.1 |
6.9 |
30% |
22.9 |
6.9 |
30% |
|
All Food |
210.8 |
62.3 |
30% |
208.0 |
62.3 |
30% |
|
Forestry |
28.2 |
7.7 |
27% |
28.2 |
7.7 |
27% |
|
Whole Economy |
290.6 |
78.1 |
27% |
300.7 |
78.1 |
26% |
This year is the first year that the published dataset includes a timeseries of Nitrogen flows and Nitrogen Use Efficiencies. The previous years included are 2019 and 2020, the years covered by the previous releases. The SNBS draws from a wide range of source data, some of which are published as timeseries. When the source data is available as a timeseries, the latest data is used in the SNBS for all years in the SNBS. If this source data were to have any revisions, those revisions would be carried through to the SNBS.
Updates have been made to the handling of Nitrogen flows relating to food. Estimates for the international import and export of food have been added, and modifications to the Nitrogen in consumed food have been made.
Quantities of internationally imported and exported food have been taken from public HMRC datasets. By combining these with estimates of the nitrogen content of food from the McCance and Widdowson’s ‘composition of foods integrated dataset’ (CoFID) the Nitrogen flows can be estimated. However, there remain no estimates for the Nitrogen flows of food imported and exported internal to the UK.
Previously the Nitrogen in consumed food was estimated by multiplying the population in ages ranges against fixed average protein consumption figures for those age ranges. This has been updated to use DEFRA’s family food datasets on average consumption of food broken down by type of food, e.g. tinned salmon. When combined with the CoFID and the population figures, an estimate which will take into account year-to-year changes in patterns of food consumption can be made. This gives similar figures to the previous method of estimating food consumption.
The impact of these SNBS methodological changes on NUEs would be limited to the whole economy NUE, as this is the only NUE which uses the updated methodology flows. Any changes in the other NUEs are due to updates in the source datasets themselves.
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