Rich McDowell used to be very precise and no-nonsense with scientific facts and cause and effect before he became a sort of unofficial roving ambassador for the superphosphate industry a few years ago. Now, outside of peat soils, the form of P fertiliser used apparently doesn’t matter. The fact that the average concentrations of filterable reactive phosphorus (ie dissolved P, more or less) at testing sites over the period 1994-2013 has decreased on more sites than have increased is implied to be a major achievement (interview of Rich by Tim Fulton, Farmers Weekly online, 5 Feb). To me, this is nonsense. Firstly, where is the data on the actual changes in concentrations? Is the mean and average up or down or sideways? Etc, etc. Certainly, fencing off waterways, riperian strips, planting susceptible areas in native bush have helped reduce P run-off. But as Rich knows, the single biggest improvement by far will be made by changing from soluble P to RPR, at no cost – in fact a saving – to the farmer. It is misleading to say “The work found little evidence the improvement was caused by a ‘change to’ low water-soluble phosphorus fertilisers”. What forms of ‘low-soluble P’? How many monitoring sites? How many years?