This research estimates farm gate phosphorus balances and use efficiencies across 147 specialist dairy farms over a seven year period (2006-2012) using nationally representative data and the Republic of Ireland as a case study. This period coincides with the introduction of phosphorus controls in agricultural production under EU Nitrates Directive based regulations. Results indicate that P balances declined by 50 per cent over the study period from 11.9 in 2006 to 6.0 Kgs Ha-1 in 2012. This decline was driven by a reduction in chemical fertiliser imports of 6.5 Kgs Ha-1 and is equivalent to a reduction of 281 kgs of P across the average farm and 2,392 tonnes of P across the weighted sample. This represents a cost saving of €812 per annum across the average farm and €6.89 million for the weighted sample over the study period. Phosphorus use efficiency also improved over the period from 60 per cent in 2006 to 78 per cent in 2012, peaking in 2011 at 88.3 per cent. Results of a random effects panel data model indicate that P balance and use efficiency are significantly influenced by factors such as fertiliser prices, stocking rates, land use potential, contact with extension services and rainfall patterns.