Phosphate potential and phosphate capacity of soils

A multivariate approach to the response of lucerne plants to varying soil conditions in pots

“…The observation of a reduction in available P with increasing Ca levels is corroborated by the results of Clarke & Peach (1960) and Jensen (1970). There is also evidence to suggest that soil reaction does not directly affect the availability of P (Reeve & Sumner 1970) and that soil temperature and moisture are more important (Simpson «fe Lipsett 1973).…”

The Determination of Desorption Isotherms for Soil Phosphate Using Low Volumes of Solution and an Anion Exchange Resin

“…A control experiment in which air was bu i bled through 5 1 of Small differences in pH in the region 6 to 7 have large effects on the ratios of H2P04:HPOc -:CaHPO, ions in solution (Larsen, 1965). Phosphate concentrations were converted to monocalcium phosphate potentials (Aslyng, I 954) taking account of calcium hosphate complex ion formation (Larsen, 1965;Jensen, 1970). Plotte B in this way, resin 4 -…”

Effect of pH and exchangeable metals on phosphate adsorption by soils

“…Many studies have shown that phosphate adsorption by soils varies with the nature of the ionic composition and the ionic strength of the supporting matrix solution (Helyar et al, 1976a;Robarge and Corey, 1979). It has been shown that increasing the concentration of nitrate and chloride salts of Ca, Mg, Na, K, and NH^ increases the adsorption of phosphate by aqueous suspensions of soils, clay, and hydrous oxides of Fe and Al (Kurtz et al, 1946;Clark and Peech, 1960;Fordham, 1963;Jensen, 1970). Also, in a study designed by Sims and Ellis (1983) to investigate the change in phosphate adsorption associated with aging of Al hydroxide suspension, they showed that reducing the ionic strength of the Al-OH suspension by dialysis produced gibbsite and caused an 80-90% decrease in phosphate adsorption maxima, as calculated by the Langmuir model.…”

“…In fact, numerous studies have shown that increasing concentration of nitrate and chloride salts of Ca, Mg, Na, and K increases the adsorption of phosphate by soils, clay, and hydrous oxides of Fe and M (Kurtz et al, 1946;Clark and Peech, 1960;Fordham, 1963;Jensen, 1970). In addition, many studies have shown that phosphate adsorption by soils vary with the nature of the ionic composition and the ionic strength of supporting matrix solution (Helyar et al, 1976a;Robarge and Corey, 1979;Sims and Ellis, 1983).…”