Chemical Fractions of Phosphorus: The Effect of Soil Orders, Soil Properties, and Land Use

ABSTRACT

Low availability of phosphorus (P) in Turkish soils is a significant problem of agricultural production depending on carbonates in slightly weathered and iron/aluminum oxides in highly weathered soils. Thus, crop-based P fertilization along with inherited nature of P partition can lead to changes in the amounts and geochemical fractions of phosphorus. For this reason, horizon-based surface samples were taken from 16 soil series that belong to four orders with different pedotransfer functions. The geochemical phosphorus fractions were sequentially extracted by sodium bicarbonate (NaHCO₃), sodium hydroxide (NaOH), citrate-dithionite-bicarbonate buffer system (CBD), hydrochloric acid (HCl), and aqua-regia. Results indicated that weathering sequence was inversely related to plant available P fractions. The fertilizer P was possibly converted to HCl-extractable (Ca-Pi) fraction in calcareous soils through NaOH-Po and NaHCO₃-Po fractions whereas it accumulated in the CBD-P fraction in relatively weathered soils. The carbonates and Al/Fe oxides were most significant constituents in P partitioning as consequences of parent material and weathering chronosequence.

KEYWORDS:

• Land use
• parent material
• phosphorus
• sequential fractionation
• soil chemistry

Funding

This study was financially supported by the Scientific Research Foundation of Süleyman Demirel University with the project number of 4531-YL2-15.

Additional information

Funding

This study was financially supported by the Scientific Research Foundation of Süleyman Demirel University with the project number of 4531-YL2-15.