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Runoff and Leachate Phosphorus and Nitrogen Losses from Grass‐Vegetated Soil Boxes Amended with Biosolids and Fertilizer
Author(s) -
Silveira Maria L.,
O'Connor George A.,
Lu Yanyan,
Erickson John E.,
Brandani Carolina,
Kohmann Marta M.
Publication year - 2019
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2019.03.0106
Subject(s) - biosolids , surface runoff , fertilizer , leachate , environmental science , phosphorus , soil water , agronomy , nutrient , hydrology (agriculture) , environmental engineering , environmental chemistry , chemistry , ecology , soil science , geology , biology , geotechnical engineering , organic chemistry
Recent evidence suggests an upward trend in surface water phosphorus (P) concentrations in many segments of Florida, including the upper basin of the St. Johns River, a region that currently receives about two‐thirds of the state Class B biosolids land application. Concerns about water quality in this area are encouraging reexamination of the regulations governing biosolids programs. The objectives of this study were (i) to identify and thoroughly characterize the main biosolids sources routinely applied in the region, and (ii) to evaluate runoff and leachate N and P losses from a typical Florida Spodosol amended with biosolids or commercial inorganic fertilizer. Biosolids and inorganic fertilizer were surface applied uniformly at a rate equivalent to ∼114 kg P ha −1 , which corresponded to a typical P load associated with nitrogen (N)‐based biosolids application. Soluble reactive P (SRP) was the predominant form of P lost in runoff and leachate. Inorganic P fertilizer increased flow‐weighted runoff total P concentrations nearly 60‐fold relative to control treatment (0.4 vs. 22 mg P L −1 for control and fertilizer treatments, respectively). With exception of biological P removal (BPR) biosolids, all other tested biosolids yielded flow‐weighted runoff P concentrations similar to untreated soils. Cumulative P and N losses (as a percentage of P and N applied) were greater from commercial inorganic fertilizer (∼38% of P and 46% of N) than any biosolids source (3% of P and 6% of N). Results demonstrate the value of water‐extractable P (WEP) as an indicator of biosolids P loss potential. Core Ideas Biosolids presented a lower risk of P and N losses than inorganic fertilizer. Nitrogen and P lability varies significantly depending on the biosolids treatment process. Data supported the usefulness of water‐extractable P as an indicator of biosolids P loss potential. More field research is warranted to understand nutrient dynamics in biosolids‐amended soils.