# The Nutrient Action Programme Regulations (Northern Ireland) 2019, Paragraph 10


Classification of soil analysis results into indices: The Olsen extractable phosphorus concentration in soil is classified into an index according to the following scale.
Soil phosphorus index
Olsen extractable phosphorus (P) (mg P/l)
0
0 – 9
1
10 – 15
2-
16 – 20
2+
21 – 25
3
26 – 45
4
46 – 70

---
Source: https://www.legislation.gov.uk/nisr/2019/81/schedule/5/paragraph/10 (the official version)
Page: https://openlegislation.uk/nutrient-action-programme-regulations-northern-ireland-2019/schedule-5/paragraph-10
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.