As global population rises there is added pressure on agricultural systems to intensify. On the other hand International organizations call their members to commit to environmental protection, including water quality. In Europe agriculture is a major water pollutant, with Phosphorus (P) considered to be contributing highly to water quality degradation. Hence, controlling phosphorus fertilizer use should be a priority. As farmers are responsible for the amount of phosphorus fertilization on their farm, they are expected to be aware of their soil P status. Farmers are advised to soil test their farms before they allocate P fertilizers, based on the assumption that soil test result will assist them in making informed decisions, and lately policy design discussions mention inclusion of soil testing in the agricultural policies regulations. To ensure the correctness of this decision a good understanding of the relation between soil testing and P fertilizer allocation is required. This paper examines dairy farm systems in Ireland, where farmers are strongly encouraged to soil test their farms regularly. National data were used in a censored tobit model to investigate the relation between a farmer s decision to soil test and Phosphorus fertilizer use intensity, among other factors. Results indicate a negative relationship suggesting that soil testing leads to reduced P fertilizer use. Acknowledgement : The authors would like to thank the Teagasc Agricultural Economics and Farm Surveys department for the data, as well as, Dr. A. Lymberopoulos and Dr. D. Chatziplis for their invaluable help.