title: Relative movement and soil fixation of soluble organic and inorganic phosphorus.
abstract: There is considerable concern about pollution of surface waters with P. Although most of the research has focused on inorganic P in surface runoff, it has recently become possible to easily follow the fate of soluble organic P forms in soils and waters. Two experiments were performed to compare the relative mobility and soil fixation affinity of orthophosphate monoesters, orthophosphate diesters, and soluble inorganic P. We used three P substrates, 4-methylumbelliferyl phosphate (MUP), deoxyribonucleic acid (DNA), and KH(2)PO(4) in (i) a soil column experiment and (ii) a soil P adsorption test tube experiment. Shortly after columns were prepared, approximately two pore volumes of 0.005 M CaCl(2) were passed through 25 cm length columns containing 10 cm of loamy sand amended with approximately 10 mg P as MUP, DNA, or KH(2)PO(4) above 15 cm of nonamended loamy sand. The total net quantity of 757.8 microg P 2L(-1) of orthophosphate diesters in the leachate from the DNA columns exceeded the net quantity of orthophosphate monoesters in leachate from the MUP columns (4.6 microg P 2L(-1)) and soluble inorganic P from the KH(2)PO(4) columns (34.0 microg P 2L(-1)). Adsorption of soluble organic and inorganic P in the test tube experiment yielded similar results: DNA, containing orthophosphate diesters, had a relatively low affinity for soils. In both experiments, high concentrations of other P compounds were identified in samples treated with organic P substrates, suggesting enzymatic hydrolysis by native soil phosphatase enzymes. These findings indicate that repeated application of organic forms of P could lead to significant leaching of P to ground water.
authors.affiliation: Department of Plant and Soil Science, University of Vermont, Burlington, 05405, USA.
authors.forename: Brandon H
authors.initials: BH
authors.lastname: Anderson
authors.forename: Frederick R
authors.initials: FR
authors.lastname: Magdoff
mesh_terms: D000327:Adsorption; D004247:DNA / Q000378:metabolism; D004787:Environmental Pollution; D006923:Hymecromone / Q000031:analogs & derivatives / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D017680:Potassium Compounds / Q000378:metabolism; D012987:Soil; D012995:Solubility; D014707:Vermont
chemical_list: D010710:Phosphates; D017680:Potassium Compounds; D012987:Soil; D010758:Phosphorus; C005359:4-methylumbelliferyl phosphate; D006923:Hymecromone; D004247:DNA; C013216:potassium phosphate