Soil organic phosphorus in Eucalyptus plantations, Brazil: extraction methods

ABSTRACT

In-depth knowledge of total soil organic phosphorus (TP_O) as a potential P source for plants allows for a comprehensive understanding of the adoption of an efficient management system of phosphorus fertilization in forest plantations. Thus, we aimed to compare three TP_O extraction methods (Hedley; Bowman; Bowman and Moir) in different Eucalyptus plantations on strongly weathered soils. The TP_O concentrations obtained by the “Hedley” (mean of 130 mg kg^–1), and “Bowman and Moir” methods (mean of 131 mg kg^–1) were similar. The “Bowman” method extracted less than 50 % of the TP_O content extracted by the other methods. Both “Hedley” and “Bowman and Moir” methods showed similar TP_O extraction efficiency compared to TP determined by acid digestion. However, the “Hedley” method is the most expensive and time-consuming analytical technique. In view of this, the NaOH+Na₂EDTA extractor (Bowman and Moir) would be the most suitable since, in addition to showing high extraction efficiency, it offers fast analysis execution, low analytical error, and lower cost.

basic EDTA extraction; forest soils; phosphorus fractionation; sequential acid-base extraction