# The Nutrient Action Programme Regulations (Northern Ireland) 2019, Paragraph 4


Time of sampling: Sampling every fourth year shall be satisfactory as a basis for phosphorus fertiliser recommendations. A field shall not be sampled for phosphorus until at least three months after the last application of any fertiliser (organic or chemical) containing this nutrient.

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Source: https://www.legislation.gov.uk/nisr/2019/81/schedule/5/paragraph/4 (the official version)
Page: https://openlegislation.uk/nutrient-action-programme-regulations-northern-ireland-2019/schedule-5/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.