Farmers have asked me what I think of SurePhos. Given the huge resources Ballance has at its disposal, and the pre-release hype, the specs of the product left me feeling underwhelmed; sad even. But one good thing; by advertising it as a fertiliser that has 75% less P runoff loss (relative to super in much smaller font), Ballance have, at last, formally admitted that the use of super does indeed result in unnecessary P losses to the environment. The extent of this loss is deliberately under-estimated in the Overseer P model; by about 80% I think. Regional Councils take note!
I think that SurePhos is about 87% super, mixed or ‘reverted’ with about 5% MgO and 8% lime. This would reduce the total P to the 7.8% P claimed, and the water-soluble P to about 2% P. The citric acid solubility should ideally be at least 7%P, or 90% of the total. This is because, if all the P originates from the Moroccan-occupied Boucraa and other non-RPR manufacturing rocks, the difference between the citsol P and the total P will have very questionable agronomic value. I explained why in publications in the 1980s. If the citric P is lower than 6.7% P, it would be like a throwback to the terribly-performing Christmas Island phosphate supers of the 1970s.