Rapid population growth and the fact that phosphorous is a limited resource implies that the question regarding an efficient use of phosphorus is of great importance, and consequently,that the phosphorous use efficiency should be as high as possible. The view on phosphorous use efficiency, and how this is calculated, has varied over time. This has had great implications on what type of research that has been conducted, which have resulted in an inconsistency between the academic?s view on the subject and recommendations received by farmers. The purpose of this paper is to calculate the phosphorus use efficiency in the Swedish long term fertility experiments.