Abstract
AbstractDomestic sewage treatment plants (STPs) that discharge partially treated wastewaters to surface waters contribute to eutrophication. A number of Allophanic soils have shown promise as a filter substrate to remove dissolved reactive phosphorus (DRP) from wastewaters. Once the phosphorus (P) sorption capacity of the soil is exhausted, it can potentially be applied to land as a soil amendment to recycle P for productive use. In this study, Allophanic soil that was P‐enriched by wastewater treatment (WTS) was evaluated for its agronomic effectiveness in a glasshouse pot experiment in which ryegrass (Lolium multiflorum) was grown on Ohakune silt loam. The ability of WTS to supply P for ryegrass growth was compared with a soluble phosphorus source (mono‐calcium phosphate, MCP). The WTS had a total P (TP) concentration of 8128 mg TP/kg oven‐dried soil. As the initial P status of the Ohakune soil was very low, the cumulative dry matter yields increased significantly with increased additions of WTS and MCP. The WTS was highly effective at increasing available P in the soil, as measured by Olsen P and ryegrass yield and P uptake. The soluble fertiliser P value of WTS was estimated to be equivalent to 61% of MCP applied at the same rate. Therefore, the results show that WTS is an effective P source for plant growth and its application to soil has the potential to recycle both the soil and the P it contains.
Published Version
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