Phosphate sorption by calcium carbonate in some soils of the Mediterranean part of Spain

Soil and Fertilizer Phosphorus and Crop Responses in the Dryland Mediterranean Zone

“…For that reason, "active" CaC03 (ACCE), i.e., the fine-sized CaC03 which reacts with ammonium oxalate (Drouineau, 1942), or the clay-sized CaC03 is determined. In 36 soils from different locations in Spain, Borrero et al (1988) found a good correlation between ACCE and clay-sized CaC03 (claysized CaC03 = -0.5 + 0.72 ACCE; r = 0.98; P < 0.001). The CaC03 content of the clay fraction may, in practice, be estimated from the CCE values (Fig.…”

“…Little information is available on the specific surface areas of soil carbonates in Mediterranean areas. Borrero et al (1988) found widely different values, but, on a soil basis, the CaC03 surface areas were lower than 12m 2 g-1 soil. In calcareous soils of Azerbaijan, Abedi and Talibudeen (1974) found that the specific surface area of CaC03 ranged between 3 and 373 m 2 g-l and was inversely correlated with total CaC03 in the soil; total surface area of CaC03 ranged from 0.5 to 4m 2 g-1 soil.…”

“…On removal of CaC03 from a group of 36 Mediterranean Spanish soils, Borrero et al (1988) found an average P sorption capacity of O.13l1mol P m -2 (equilibrium P concentration = 20I1M), a value not very different from that of synthetic calcites, and about one order of magnitude less than that of Fe oxides. The contribution of CaC0 3 to P sorption in soils must be closely correlated with its total surface area, since, as the above results suggest, P sorption per unit area has a relatively well-known value.…”

“…Determination of the specific surface area therefore appears desirable. Gal et al (1974) and Borrero et al (1988).…”

Effects of soil properties on phosphorus fractions in subtropical soils of Iran

“…These methods are based on the selective extraction of operationally defined P fractions by using single extractants in a sequential manner (Hieltjes and Lijklema, 1980;Olsen and Sommers, 1982;Jiang and Gu, 1989;Ruiz et al, 1997). In calcareous soils, P is mainly bound to adsorption surfaces at low (<10-4.5 M) concentrations of orthophosphate in solution (Borrero et al, 1988;Tunesi et al, 1999), whereas it is mainly precipitated as Ca phosphates at higher concentrations (Castro and Torrent, 1998;Tunesi et al, 1999). Soils that dominate humid temperate and tropical regions are highly weathered, acidic and dominated by large quantities of sesquioxides.…”