Effect of long-term fertilization on phosphorus fractions in different soil layers and their quantitative relationships with soil properties

Investigating the dynamics and distribution of soil phosphorus (P) fractions can provide a basis for enhancing P utilization by crops. Four treatments from 29-year long-term experiment in black with maize cropping were involved this study: no fertilizer (CK), inorganic nitrogen potassium (NK), nitrogen, phosphorus, (NPK), NPK plus manure (NPKM). We analyzed different layers using modified Hedley sequential method. The NPKM treatment significantly increased total 0.6-1.6 times layers. Olsen-P concentration far exceeded environmental threshold (50.6 mg kg-1) 0-60 cm profile. Moreover, concentrations proportion labile partially (Pi) (i.e., NaHCO3-extracted Pi, NaOH-extracted dilute HCl-extracted Pi) to sum all (Pt) profile higher than treatment, indicating that could promote transformation non-labile into more forms soil, possibly reducing fixation particles. Soil organic matter, Mehlich-3 extractable iron (Fe), organic-bound aluminum fertilization, main factors influencing differences 0-20 layer. mineral components, i.e., free Fe oxide CaCO3, subsoil. process varied layer fertilization. Application increase (Olsen) various layers, thus should reduce requirement crop growth potential damage.