Evaluation of phosphorus in thermally converted sewage sludge: P pools and availability to wheat

TY - JOUR

T1 - Evaluation of phosphorus in thermally converted sewage sludge

T2 - P pools and availability to wheat

AU - Mackay, Jessica E.

AU - Cavagnaro, Timothy R.

AU - Jakobsen, Iver

AU - Macdonald, Lynne M.

AU - Grønlund, Mette

AU - Thomsen, Tobias P.

AU - Müller-Stöver, Dorette Sophie

PY - 2017

Y1 - 2017

N2 - Aims: Dried sewage sludge (SS) and the by-products of four SS thermal conversion processes (pyrolysis, incineration and two types of gasification) were investigated for phosphorus (P) availability. Methods: A sequential extraction was used to determine the distribution of P among different P pools. After mixing materials with soil, availability of the P was determined with soil P extractions and in a growth experiment with wheat. Results: Thermally converted SS contained a greater proportion of P within recalcitrant pools than dried SS. Despite having very different P pool distributions, the incinerated and dried SS provided similar amounts of P to plants. Plant P supply from dried and incinerated SS was lower than the comparable soluble P treatment (50 mg P kg−1), but higher than a soluble treatment at a lower rate (20 mg P kg−1). Plant P uptake in gasified and pyrolysed treatments was only marginally greater than uptake in a control (no P) treatment. Plant P uptake correlated most closely with diffusive gradients in thin films (DGT) P analysis of soil-material mixes. Phosphorus availability in the dried and incinerated SS treatments increased over time. Conclusions: We propose that the dried and incinerated SS have potential as slow release P fertilisers in low pH soils.

AB - Aims: Dried sewage sludge (SS) and the by-products of four SS thermal conversion processes (pyrolysis, incineration and two types of gasification) were investigated for phosphorus (P) availability. Methods: A sequential extraction was used to determine the distribution of P among different P pools. After mixing materials with soil, availability of the P was determined with soil P extractions and in a growth experiment with wheat. Results: Thermally converted SS contained a greater proportion of P within recalcitrant pools than dried SS. Despite having very different P pool distributions, the incinerated and dried SS provided similar amounts of P to plants. Plant P supply from dried and incinerated SS was lower than the comparable soluble P treatment (50 mg P kg−1), but higher than a soluble treatment at a lower rate (20 mg P kg−1). Plant P uptake in gasified and pyrolysed treatments was only marginally greater than uptake in a control (no P) treatment. Plant P uptake correlated most closely with diffusive gradients in thin films (DGT) P analysis of soil-material mixes. Phosphorus availability in the dried and incinerated SS treatments increased over time. Conclusions: We propose that the dried and incinerated SS have potential as slow release P fertilisers in low pH soils.

KW - Bioash

KW - Biochar

KW - Diffusive gradients in thin films (DGT)

KW - Sequential phosphorus extraction

KW - Sewage sludge

KW - Wheat

U2 - 10.1007/s11104-017-3298-6

DO - 10.1007/s11104-017-3298-6

M3 - Journal article

AN - SCOPUS:85020233785

SN - 0032-079X

VL - 418

SP - 307

EP - 317

JO - Plant and Soil

JF - Plant and Soil

IS - 1-2

ER -