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Total P (TP), total participate P (PP), total dissolved P (TDP), molybdate reactive P (MRP) and dissolved organic P (DOP) were determined in waters from pipe-drains (at 65-cm depth) from the Broadbalk Experiment at Rothamsted Research, UK. Average TP and PP exceeded 1 mg L-1 in about half of the 12 plots receiving superphosphate for the 5 measurements taken between December 2000 and April 2001. Ranging between 33.8% and 87.3% of TP, PP was the largest P fraction in drainage waters, with DOP, ranging from 0.5% to 26.2% of TP, being the smallest fraction. Mean proportions of PP, MRP and DOP in TP in drainage waters were 63.4%, 32.5% and 4.1%, respectively. These findings support previous findings that P losses from soil to drainage waters were much larger than previously thought, and could therefore make a significant contribution to eutrophication.
Total P (PP), total dissolved P (TDP), molybdate reactive P (MRP) and dissolved organic P (DOP) were determined in waters from pipe-drains Broadbalk Experiment at Rothamsted Research, UK. Average TP and PP exceeded 1 mg L-1 in about half of the 12 plots receiving superphosphate for the 5 measurements taken between December 2000 and April 2001. Ranging between 33.8% and 87.3% of TP, PP The largest P fraction in drainage waters, with DOP, ranging from 0.5% to 26.2% of TP, being the smallest fraction. Mean proportions of PP, MRP and DOP in TP in drainage waters were 63.4%, 32.5% and 4.1% respectively. These findings support that P losses from soil to drainage waters were much larger than previously thought, and could therefore make a significant contribution to eutrophication.