Page 211 - C:\Users\am_se\OneDrive - Higher Education Commission\Desktop\FlipBook\

International Conference on

Recent Trends in Environmental Sustainability

ESCON22/SWMR/01
Contrasting effects of sewage sludge and sewage sludge-derived biochar on wheat straw
mineralization in sandy and clayey textured soils

1*
1
Muhammad Riaz , Maryam Adil
1 Department of Environmental Sciences & Engineering, Government College University
Faisalabad, Pakistan
Correspondence: mr548@ymail.com

Abstract
Deleterious effects of sewage sludge (SSL) on soil quality can be overcome by converting SSL
into SSL-biochar (SSL-B). Sewage sludge was pyrolyzed into biochar at 600 °C for 30
minutes. Sandy and clayey textured soils were amended with wheat straw, SLL and SLL-B and
incubated for 30 days following a completely randomized experimental design. Sewage sludge
and SSL-B had contrasting effects on wheat straw decomposition, but cumulative CO2 efflux
was higher in clayey than sandy soil. Sewage sludge biochar caused positive priming of native
soil C in clayey whereas suppressed wheat straw decomposition in sandy soil. Microbial
biomass C was significantly higher in SSL-B and wheat straw treatments in both soils. Cold
water-, hot water- and salt-extractable organic C fractions indicated significant changes in soil
organic matter quality. Changes in specific ultraviolet absorbance (SUVA), aromaticity and,
hydrophobic and hydrophilic properties of dissolved organic C suggested contrasting effects
of SSL and SLL-B on soil organic C quality. Total organic C contents were significantly higher
in both soils when wheat straw was amended with SSL-B and SSL. Significantly less values
of microbial metabolic quotient (qCO2) in wheat straw amended SSL-B than wheat straw
amended with SSL could suggest higher microbial C utilization efficiency in both soils. Our
study provided evidence that SSL can be better utilized as SSL-B to improve microbial activity,
soil organic C and soil biochemical quality in nutrient and organic matter depleted soils in
semi-arid regions.
Keywords: Biochar; Soil organic C; Sewage sludge; Microbial activity; Soil quality

Department of Environmental Sciences, COMSATS University Islamabad, Vehari Campus

178