Nutrient transport, shear strength and hydraulic characteristics of topsoils amended with mulch, compost and biosolids

Anthropogenic disturbance of soils can disrupt soil structure, diminish fertility, alter soil chemical properties, and cause erosion. Current remediation practices involve amending degraded urban topsoils lacking in organic matter and nutrition with organic amendments (OA) to enhance vegetative grow...

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Published in:The Science of the total environment 2024-03, Vol.918, p.170649-170649, Article 170649
Main Authors: Pamuru, Sai Thejaswini, Morash, Jennifer, Lea-Cox, John D., Ristvey, Andrew G., Davis, Allen P., Aydilek, Ahmet H.
Format: Article
Language:English
Subjects:
Biosolids
Composting
Hydraulic conductivity
Nitrogen
Nutrient leaching
Nutrients
Organic amendments
Phosphorus
Phosphorus - chemistry
Sewage - chemistry
Shear
Shear Strength
Soil - chemistry
Soil Pollutants - analysis
Soils
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Summary:Anthropogenic disturbance of soils can disrupt soil structure, diminish fertility, alter soil chemical properties, and cause erosion. Current remediation practices involve amending degraded urban topsoils lacking in organic matter and nutrition with organic amendments (OA) to enhance vegetative growth. However, the impact of OAs on water quality and structural properties at rates that meet common topsoil organic matter specifications need to be studied and understood. This study tested three commonly available OAs: shredded wood mulch, leaf-based compost, and class A Exceptional Quality stabilized sewage sludge (or biosolids) for nutrient (nitrogen and phosphorus) water quality, soil shear strength, and hydraulic properties, through two greenhouse tub studies. Findings showed that nitrogen losses to leachate were greater in the biosolids amended topsoils compared to leaf-compost, mulch amended topsoils, and control treatments. Steady-state mean total nitrogen (N) concentrations from biosolids treatment exceeded typical highway stormwater concentrations by at least 25 times. Soil total N content combined with the carbon:nitrogen ratio were identified to be the governing properties of N leaching in soils. Study soils, irrespective of the type of amendment, reduced the applied (tap) water phosphorus (P) concentration of ∼0.3 mg-P/L throughout the experiment. Contrary to the effects on N leaching, P was successfully retained by the biosolids amendment, due to the presence of greater active iron contents. A breakthrough mechanism for P was observed in leaf compost amended soil, where the effluent concentrations of P continued to increase with each rainfall application, possibly due to an saturation of soil adsorption sites. The addition of OAs also improved the strength and hydraulic properties of soils. The effective interlocking mechanisms between the soil and OA surfaces could provide soil its required strength and stability, particularly on slopes. OAs also improved soil fertility to promote turf growth. Presence of vegetative root zones can further reinforce the soil and control erosion. [Display omitted] •Different types of OAs improved shear and soil hydraulic properties.•Treated biosolids addition improved P retention in soils, while it incurred N losses.•Mulch caused lower outputs of N and P in the leachate.•P was retained by leaf-compost and N leaching reduced over time.•Across soil-water-plant nexus, leaf compost was the preferred OA.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2024.170649