• Olsen-P;
  • ABC Protector;
  • bioavailable phosphorus


In this study, we re-examined the common practice of intensive P fertilization in altered wetland soils even when soil test (Olsen-P) indicates sufficient P levels (>10 mg/kg). We tested the effects of P fertilization on crop performance and P leaching in 36 lysimeters (1.5 m3) filled with peat, marl or alluvial materials and compared a new bone-char-based fertilizer to the common superphosphate. The lysimeter experiment consisted of the two fertilizer types, two application rates and a typical crop rotation of setaria (Setaria italica), pea (Pisum sativum) and tomatoes (Lycopersicon esculentum). By the end of each crop rotation, the yield was evaluated relative to P-fertilization rates and soil-test P. P fertilization resulted in increased Olsen-P, soil-solution P and P loss through leachates and a slight quality yield advantage in pea and tomato with no increase in yield of any crop. P budget calculations showed that plant uptake was not affected by the amount or type of applied P. We concluded that P fertilizer application should be significantly reduced because of limited crop response and increased P concentrations in leachates that may increase P loss to waterways especially in the marl soils. The ABC Protector exhibited slow P release, but its environmental implications should be further studied.