TY - JOUR

T1 - Phosphorus availability of sewage sludges and ashes in soils of contrasting pH

AU - Lemming, Camilla

AU - Simmelsgaard Nielsen, Martin Toft

AU - Jensen, Lars Stoumann

AU - Scheutz, Charlotte

AU - Magid, Jakob

PY - 2020

Y1 - 2020

N2 - Background:Little is known about the relationship between plant availability of P in different sludges and their derived ashes, its development over time and its interaction with soil pH. Aim:This study addresses this knowledge gap, by investigating the P availability and fractions of six sludges produced under different conditions and the incineration ashes derived from five of these,plusthe effect of time (84 days) and soil pH on P availability. Methods:These materials were applied to two similar soils with contrasting pH (5.8 and 7.8), based on the assumption that lower pH would favor plant availability of P from these sources. Triple super phosphate and a control (no P addition) were included as references. Results:The relative P fertilizer availability (RFA) in soil of both sludges (18-77%) and ashes (0.1-25%), measured as water extractable P, was found to be highly dependent on their origin. While the P availability of sludges was strongly affected by soil pH, ash P availability showed either no or little soil pH effect, in contrast to our expectations. For the sludges, RFA was negatively correlated to the ratio (Fe+Al)/P in both pH soils and positively correlated to sludge water extractable P in the higher pH soil. For the ashes, the ratio Fe+Al to P and the pH reaction of ashes in water were strongly negatively correlated with RFA in the lower pH soil. Ca/P ratios did not predict RFA in either sludges or ashes. Nevertheless, we ascribe the comparably higher average RFA in sludges of 58% found in the low pH soil compared to 25% in the alkaline soil to the greater solubility of Ca-P species under lower pH. For ashes, the availability increased over time, while rather stable for sludges. Conclusion:In conclusion, the P availability of both sludges and ashes was highly dependent on their origin, and for sludges highly dependent on soil pH

AB - Background:Little is known about the relationship between plant availability of P in different sludges and their derived ashes, its development over time and its interaction with soil pH. Aim:This study addresses this knowledge gap, by investigating the P availability and fractions of six sludges produced under different conditions and the incineration ashes derived from five of these,plusthe effect of time (84 days) and soil pH on P availability. Methods:These materials were applied to two similar soils with contrasting pH (5.8 and 7.8), based on the assumption that lower pH would favor plant availability of P from these sources. Triple super phosphate and a control (no P addition) were included as references. Results:The relative P fertilizer availability (RFA) in soil of both sludges (18-77%) and ashes (0.1-25%), measured as water extractable P, was found to be highly dependent on their origin. While the P availability of sludges was strongly affected by soil pH, ash P availability showed either no or little soil pH effect, in contrast to our expectations. For the sludges, RFA was negatively correlated to the ratio (Fe+Al)/P in both pH soils and positively correlated to sludge water extractable P in the higher pH soil. For the ashes, the ratio Fe+Al to P and the pH reaction of ashes in water were strongly negatively correlated with RFA in the lower pH soil. Ca/P ratios did not predict RFA in either sludges or ashes. Nevertheless, we ascribe the comparably higher average RFA in sludges of 58% found in the low pH soil compared to 25% in the alkaline soil to the greater solubility of Ca-P species under lower pH. For ashes, the availability increased over time, while rather stable for sludges. Conclusion:In conclusion, the P availability of both sludges and ashes was highly dependent on their origin, and for sludges highly dependent on soil pH

KW - P availability

KW - sludges

KW - sludge ashes

KW - soil pH

KW - FLUIDIZED-BED GASIFICATION

KW - FERTILIZER VALUE

KW - WASTE-WATER

KW - PLANT AVAILABILITY

KW - CROP

KW - PHYTOAVAILABILITY

KW - BIOAVAILABILITY

KW - MANAGEMENT

KW - PRODUCTS

KW - DYNAMICS

UR - https://onlinelibrary.wiley.com/doi/10.1002/jpln.201900323

U2 - 10.1002/jpln.201900323

DO - 10.1002/jpln.201900323

M3 - Journal article

VL - 183

SP - 682

EP - 694

JO - Journal of Plant Nutrition and Soil Science

JF - Journal of Plant Nutrition and Soil Science

SN - 1436-8730

IS - 6

ER -