Phosphorus Leaching from Biosolids‐Amended Sandy Soils

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Abstract
Increasing emphasis on phosphorus (P)‐based nutrient management underscores the need to understand P behavior in soils amended with biosolids and manures. Laboratory and greenhouse column studies characterized P forms and leachability of eight biosolids products, chicken manure (CM), and commercial fertilizer (triple superphosphate, TSP). Bahiagrass (Paspalum notatumFlugge) was grown for 4 mo on two acid, P‐deficient Florida sands, representing both moderate (Candler series: hyperthermic, uncoated Typic Quartzipsamments) and very low (Immokalee series: sandy, siliceous, hyperthermic Arenic Alaquods) P‐sorbing capacities. Amendments were applied at 56 and 224 kg PTha−1, simulating P‐based and N‐based nutrient loadings, respectively. Column leachate P was dominantly inorganic and lower for biosolids P sources than TSP. For Candler soil, only TSP at the high P rate exhibited P leaching statistically greater (α = 0.05) than control (soil‐only) columns. For the high P rate and low P‐sorbing Immokalee soil, TSP and CM leached 21 and 3.0% of applied P, respectively. Leachate P for six biosolids was ox]/[Alox+ Feox]) based on oxalate extraction of the pre‐applied biosolids. For biosolids with PSI ≤ approximately 1.1, no appreciable leaching occurred. Only Largo cake (PSI = 1.4) and pellets (PSI = 1.3) exhibited P leaching losses statistically greater than controls. The biosolids PSI appears useful for identifying biosolids with potential to enrich drainage P when applied to low P‐sorbing soils.
Funding Information
  • Water Environment Research Foundation (99-PUM-2T)