Phosphorus immobilization in biosolids-impacted soils: Influence of amendment type and soil chemistry on environmental and agronomic outcomes.
Freitas AM, Nair VD, Osborne TZ, Vardanyan L, Ellis ALR
Soil Health
If your county applies treated sewage sludge to nearby pastures, the phosphorus washing off those fields is likely feeding the algae blooms that choke the rivers and springs you swim in — and this research maps which soil fixes actually work.
Farmers sometimes spread treated sewage solids on fields as fertilizer, but too much phosphorus can wash into waterways and cause massive algae blooms that kill fish and foul drinking water. Scientists tested a range of materials — from lime to wood charcoal to industrial water-treatment waste — to find out which ones could lock that extra phosphorus into the soil. They found that aluminum- and iron-rich materials worked best overall, but pine biochar stood out as a safer, balanced option that reduced phosphorus runoff without starving the grass of nutrients it needs to grow.
Key Findings
Aluminum- and iron-based amendments reduced water-soluble phosphorus by an average of ~67% across all biosolids-impacted soils.
Pine biochar achieved a 44% reduction in plant-available phosphorus without compromising agronomic parameters or posing chemical risks, making it the most balanced amendment tested.
Calcium- and magnesium-based materials (dolomite, lime) were the least effective, reducing phosphorus availability by only ~19% on average.
chevron_right Technical Summary
Researchers tested seven soil amendments to reduce harmful phosphorus runoff from sewage-biosolids-treated farmland in Florida, finding that aluminum- and iron-based treatments cut dissolved phosphorus by about 67%, while pine biochar offered a gentler 44% reduction without hurting crop productivity or introducing new chemical risks.
Abstract Preview
Biosolids application on farmland provides a sustainable means of nutrient reuse while supporting crop production; however, it can promote phosphorus (P) accumulation and leaching, increasing the r...
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