Residual phosphorus solubility for an acid, clayey, forested soil in the presence of oxalate and citrate

• Published in: Canadian journal of soil science 1989-02, Vol.69 (1), p.111-117
• Main Authors: Comerford, N.B, Skinner, M.F
• Format: Article
• Language: English
• Subjects: acid soils; Agronomy. Soil science and plant productions; Biological and medical sciences; citrates; clay soils; forest soils; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Nitrogen, phosphorus, potassium fertilizations; orthophosphates; oxalates; Phosphorus fertilization; phosphorus uptake; Pinus radiata; Soil-plant relationships. Soil fertility. Fertilization. Amendments; solubility; sorption isotherms; superphosphate
• ISSN: 0008-4271; 1918-1841
• DOI: 10.4141/cjss89-010

A highly weathered, clayey soil was sampled 14 yr after a Pinus radiata stand was broadcast fertilized with 0, 50 and 200 kg P ha −1 as ordinary superphosphate. Incremental loadings of oxalate and citrate anions from 10 to 100 μmol of anion g −1 soil were evaluated for increased soluble, reactive P (SRP) and soluble, nonreactive (SNP) P. Sorption isotherms were compared to evaluate the effect of the previous fertilization on P sorption by the soil material sampled, and also to measure SNP displacement by orthophosphate-P. A portion of the SNP pool was more readily released than SRP and orthophosphate displaced a significant amount of SNP. After 14 yr the effect of fertilization was still obvious in the sampled soil material. Much of the organic anion-soluble P was in the SRP form. Key words: Citrate, organic P, orthophosphate, oxalate, Pinus radiata, residual P