Potential phosphorus losses in overland flow from pastoral soils receiving long‐term applications of either superphosphate or reactive phosphate rock

摘要

Abstract The forms and concentrations of P in overland flow were measured from intact pastoral soils obtained from the Winchmore long‐term P fertiliser trial. Treatments under evaluation were soils that received either 0, 188, 250 or 376 kg superphosphate ha?1 yr?1, or 175 kg reactive phosphate rock (RPR) ha?1 yr?1. The objective was to determine the magnitude of potential P transfers from soil to water following P fertilisation, and to determine if losses were different following RPR fertilisation compared with superphosphate. Overland flow was induced by the application of artificial rainfall at 15 mm h?1, maintained for 1 h after flow commenced. Concentrations of dissolved reactive P (DRP) and total P (TP) mirrored the long‐term application rates, although prior to a fresh application of P, soils with P applied in RPR form lost more P during an event than soils with the same rate of P applied as superphosphate. After a fresh application of RPR and superphosphate treatments, up to 5.4 mg TP litre?1 was ...