Inorganic phosphorous availability and mobility in a manufactured soil

Area of Science:

• Environmental Science
• Soil Science
• Agronomy

Background:

• Manufactured soils offer sustainable alternatives to natural soils, utilizing waste materials.
• Optimizing manufactured soils is crucial to prevent adverse environmental effects from excessive fertilizer use.

Purpose of the Study:

• To investigate phosphorus (P) transformation dynamics in a manufactured soil.
• To assess the implications of P cycling for nutrient management and environmental impact.

Main Methods:

• A manufactured soil (32.5% composted green waste, 32.5% composted bark, 25% horticultural grit, 10% lignite clay) was studied over one year in controlled mesocosms.
• Leachate was collected for high-resolution monitoring of leached phosphate concentrations.
• Fertilizer application was assessed for its impact on phosphate dynamics.

Main Results:

• Leached dissolved inorganic phosphorus (DIP) increased significantly in the first 42 days, then stabilized.
• Soil organic matter mineralization and microbial activity were key drivers of DIP release.
• While P levels supported plant growth, leached P exceeded eutrophication thresholds, indicating potential risks to surface waters.

Conclusions:

• Manufactured soils require careful management to mitigate phosphorus loss.
• The current formulation may pose an environmental risk to aquatic ecosystems due to elevated phosphorus leaching.
• Further optimization of manufactured soil composition and management is necessary for sustainable use.