Sir, - John Behan (August 7th) calls for comment from me on the likely impact on water quality of fertiliser phosphorus application to forestry on shallow upland soils in the catchment of Lough Leane.
Let me say that such a combination of circumstances would not be the one I would choose if I wanted to substantiate my contention that fertiliser phosphorus is not generally a major contributor to phosphorus in rivers and lakes. Despite this, I would be surprised if it was a major factor in Lough Leane, given that the lake receives large direct inputs of treated and untreated sewage effluents which show very much the same seasonal pattern Mr Behan refers to. In other words, if my life depended on the lowering of phosphorus inputs to Lough Leane, my attentions would not be directed at fertiliser use.
Could it be that the continued attempts to implicate fertiliser phosphorus, even in situations where much more obvious sources are involved, is essentially an admission that domestic and industrial sources of phosphorus in sewage effluent are too difficult to deal with? Is it coincidental that tertiary sewage treatment is now being referred to as phosphorus removal? Is this ambiguous term meant to conjure up the notion of total removal, rather than the partial removal it is actually is. - Yours, etc.,
Dr G. W. Smillie,
Soil Science,
University College Dublin,
Dublin 4.