Extractable iron and aluminium predict the P sorption capacity of Thai soils

Abstract

The objective of this study was to determine if dithionite- and oxalate-extractable Fe and Al can be used to predict the P sorption capacity of Thai soils. Forty-five samples from diverse soil types were taken from surface and subsurface horizons of soils on sandstone, shale/limestone, granite, and basalt. The samples were analysed for P sorption, dithionite- and oxalate-extractable Fe and Al (Fed, Feo, Ald, Alo), specific surface area (SSA), and other soil properties. Generally P sorption data for these soils were slightly better fitted by the Langmuir equation than the Freundlich equation. The Langmuir P sorption maximum ranged from 35 to 1111 μg/g with a median value of 370 μg/g soil. Soils developed on basalt had higher values of P sorption maximum (xm) (range 400–1111 μg/g, median 597 μg/g) than soils on other parent materials. Fed concentrations in soils (4–74 g/kg) were much higher than Feo concentrations (0.2–13.8 g/kg) with values of Feo/Fed ranging from 0.01 to 0.28 (median 0.09), indicating that most of the free iron oxides were crystalline. Amounts of Ald and Alo were about equal with median values of 1.6 and 1.0 g/kg, respectively. About 80% of the samples had SSA values <40 m2/g. Both the P sorption maximum and Freundlich k were linearly related to SSA (R2 = 0.77, 0.74), Ald (R2 = 0.78, 0.79), Alo (R2 = 0.64, 0.74), Fed (R2 = 0.48, 0.41), Feo (R2 = 0.43, 0.72), and clay content (R2 = 0.48, 0.36). Stepwise regression indicated that 81% of the variability in P sorption by these soils could be explained by a combination of dithionite and oxalate Fe and Al, however, Ald alone is almost as effective in predicting the P sorption capacity of Thai soils.

Phosphorus-Sorption Characteristics and Phosphorus Buffer Coefficients of Some Important Soils in Lao PDR

“…Increased soil acidity, oxalateextractable Al, and the combined Al and Fe oxide factor increased P sorption at 0.2 mg P L −1 . Wiriyakitnateekul et al (2005) reported that variability in P sorption by Thai soils could be explained by a combination of oxalate-and dithionite-extractable Fe and Al. Hartono, Funakawa, and Kosaki (2005) also reported that the combined Al-and Fe-oxiderelated factor was the main predictor of P sorption in acidic upland soils in Indonesia.…”

Relationship between soil properties, p sorption characteristics and fertilizer p for optimum yield of soybean (Glycine Max (L.) Merr.) on some inceptisols in Benue

“…(Agbenin, 2003) had earlier reported evidence that clay mineral and extractable oxides of Fe and Al play an important role in P fixation in soils. In the same way, (Wiriyakitnateekul et al, 2005) reported that in Thai soils, 81% of variability in P sorption was related with extractable Fe and Al by dithionate and oxalate extraction. Also, (Maguire et al, 2001) reported that sorption of P was strongly correlated with the amounts of Al and Fe.…”

Phosphorus Sorption in Soils and Clay Fractions Developed from Different Parent Rocks in Limpopo Province, South Africa

“…Clearly, the Brazilian oxisols are extremely highly Pfixing soils relative to the soils from this study, which are moderately P-fixing [31]. Further comparison of the average Xm values for the soils that were developed from basalt, granite-basement complex, and sandstone from Thailand (assuming their data is evenly spaced) [33] and Nigeria [34] (597 and 254 mg/kg, 313 and 231 mg/kg, and 132 and 294 mg/kg, respectively) showed that the soils from this study had higher P sorption capacities. The average P X m for the soils (Table 2) were within the reported values for several acidic soils that had been developed from different parent materials in Indonesia, with values ranging from 294 to 1430 mg/kg [30,31].…”