Organic and Inorganic Forms of Phosphorus in a Calcareous Soil Planted with Four Species of Eucalyptus in Southern Iran
2009
Khanmirzaei, A. | Adhami, E. | Kowsar, S.A. | Sameni, A.M.
The objectives of the present study were to evaluate the effect of four eucalyptus species on (i) selected surface soil properties and (ii) the distribution of inorganic and organic phosphorus (P(i) and P(o)) fractions. Soil samples were collected from soil 0-20 cm deep beneath and between trees. The P(i) forms were determined by sequential extraction with sodium bicarbonate (NaHCO3-P), ammonium acetate (NH4OAc) (OAc-P), ammonium fluoride (NH4F-P), sodium hydroxide (NaOH)-sodium carbonate (Na2CO3) (HC-P), citrate dithionite (CD-P), and sulfuric acid (H2SO4) (H2SO4-P). The Po forms were sequentially extracted with NaHCO3 (NaHCO3-Po), NaOH (NaOH-Po), and H2SO4 (H2SO4-Po). The NaOH-Po was subdivided into moderately stable (NaOH-Pom) and highly stable Po (NaOH-Pos). Organic matter, clay and silt contents, total nitrogen, and available potassium of the soil beneath the trees increased. The OAc-P and HC-P forms beneath the trees were less than of that between them, which shows that these fractions probably are labile inorganic P pools. The NaHCO3-Po and NaOH-Pos forms were greater beneath the trees than those of interspaces, whereas NaOH-Pom and H2SO4-Po were not affected by plantation.
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