Chemical characteristics of phosphorus in alkaline soils from southern Australia

Abstract

This study was performed to better understand the chemical behaviour of P in a variety of alkaline soils from southern Australia. To do so, surface soil samples of 47 alkaline cropping soils from Upper Eyre Peninsula in South Australia and from western Victoria were collected. The 22 soils collected from Eyre Peninsula were Calcarosols, and those from western Victoria were Vertosols, Alkaline Duplex soils, Sodosols, and Red Brown Calcareous soils. Parameters included total and amorphous Al and Fe, organic C, organic P, CaCO3 content, P sorption characteristics, phosphorus buffer capacity, calcium lactate (Ca-Lac) extractable P, bicarbonate-extractable (Colwell) P, water-extractable P, anion exchange membrane extractable P (AEM-P), and isotopically exchangeable P (labile P). Concentrations of micronutrients in the Calcarosols were relatively low, considered to be a function of low clay contents. Given very low background Cd concentrations in the soils, it was estimated from Cd measurements that the majority of total P in the soils was derived from previous fertiliser applications. Phosphorus buffer capacities (PBCs) were relatively high in the Calcarosols and moderately high in the other alkaline soils. P sorption behaviour in the Calcarosols was a direct function of CaCO3 content, although in the other alkaline soils, amorphous Al and Fe oxides were the principal determinants of the P sorption behaviour. Both Colwell and Ca-Lac extractants dissolved non-labile P in the highly calcareous soils, whereas AEM appeared to only remove surface-adsorbed P. In addition, Colwell P values were positively related to PBC and to the slope term in the Freundlich model (Kf) when Kf > 10. It is suggested that AEM-P may be a better predictor of P availability in highly calcareous soils compared with the other extractants.

Plant: soil interactions in temperate multi-cropping production systems

“…Phosphorus is a limited and highly immobile plant nutrient and often found in fixed organic compounds, or in form of Ca phosphates and Fe and Al phosphates, which are not directly extractable by plants (Bertrand et al 2003). Several plants have developed mechanisms by which soil P can be mobilised into forms which can then be utilised by them and by plants growing in close proximity, such as that roots can interact ).…”

Influence of Incubation Period, Temperature and Different Phosphate Levels on Phosphate Adsorption in Soil

“…Surface adsorption and precipitation are the major P retention processes limiting the availability of applied P. However, the need for caution is stressed in interpreting correlation between P retention capacity (Bertrand et al, 2003) and soil properties because of the inter correlations among soil properties (Torrent, 1995). A simple correlation analysis may not be sufficient in evaluating direct influence of soil properties on P retention capacity (Zhang et al, 2005).…”

“…Soluble P compounds when added to soil react rapidly with various compounds like CaCO 3 (Bertrand et al, 2003), sand (Leclerc et al, 2001), clay (Johnston et al, 1991;Toor et al, 1997), organic matter (Daly et al, 2001), iron and aluminum oxides (Toor et al, 1997) and are quickly converted to slowly available forms (Castro and Torrent, 1995). In addition to these properties, adsorption also depends on contact time between soil and P with temperature (Indiata et al, 1999).…”

Compost effects on microbial biomass and soil P pools as affected by particle size and soil properties

“…Fertilisers with high concentrations of soluble P are used to increase plant P availability, but P availability rapidly decreases as fertiliser P reacts with Al and Fe in low pH soils and with Ca in high pH soils (Bertrand et al, 2003;Khan and Joergensen, 2009). This insoluble accumulated P can be released in particulate form into surface water and lead to eutrophication ( Song et al, 2007).…”