TY - JOUR AU - MM Nthejane, AU - CC du Preez, AU - CW van Huyssteen, PY - 2021/01/28 Y2 - 2024/03/29 TI - Relationships between agronomic and environmental phosphorus analyses of selected soils JF - Water SA JA - WSA VL - 47 IS - 1 January SE - Research paper DO - 10.17159/wsa/2021.v47.i1.9449 UR - https://watersa.net/article/view/9449 SP - AB - <p>Phosphorus (P) is an essential nutrient in crop production and is therefore typically applied as phosphatic fertilisers.&nbsp; This can induce soil P concentrations that may contribute to freshwater eutrophication.&nbsp; Soil P tests developed from a water pollution protection perspective are unlike those developed for agronomic purposes and are also not easily adapted to routine analyses.&nbsp; The aim with this study was therefore to establish whether the values of P extracted from a range of soils by various agronomic and environmental P determination methods are related or not.&nbsp; Topsoil samples were collected from virgin soils in central South Africa and treated with KH<sub>2</sub>PO<sub>4</sub> to induce different P concentrations and then incubated for 3 months, while subjected to various wetting and drying cycles.&nbsp; The samples were then analysed for P using the extractants of Bray 1, citric acid, ISFEI, Olsen, and Truog, commonly employed to establish the agronomic P status of soils.&nbsp; Environmental P status was determined with calcium chloride (CaCl<sub>2</sub>) and ammonium oxalate (DPS<sub>ox</sub>) extractants.&nbsp; Generally good relationships were found between CaCl<sub>2</sub> and ISFEI (<em>R</em><sup>2</sup> = 0.72), between DPS<sub>ox</sub> and Truog (<em>R</em><sup>2</sup> = 0.79), and between DPS<sub>ox</sub> and citric acid (<em>R</em><sup>2</sup> = 0.82).&nbsp; Agronomic P soil tests therefore have the potential to be used in regulating application of phosphatic fertilisers to ensure optimum crop yields, while simultaneously limiting freshwater pollution.&nbsp; Further field studies are, however, recommended to determine threshold values from an environmental point of view.</p> ER -