Influence of Soil Characteristics and Environmental Conditions on Seasonal Variations of Water-Soluble Phosphate in Soils

Evaluation of water and ammonium acetate tests as indices for available P in limed soils

“…Under field conditions, a practical consequence of the ionic strength effect is that the mobilization of P is promoted in autumn, when the ionic strength is diminished (Wiklander and Andersson 1974, Kuo and Jellum 1987). Eriksson (1940) noticed that the KCI fertilization may even decrease yield by depressing the solubility of soil P. Thus, the extraction results suggest that the water-soluble P gives a more accurate estimate of short-term available reserves than the acetateextractable P. Table 2 demonstrates that the P tests responded dissimilarly also to an increase in pH.…”

Meteorological and management influences on seasonal variation in phosphorus fractions extracted from soils in western Ireland

“…Perrott et al, 1990;Tate et al, 1991a;Magid and Nielsen, 1992;McDowell and Trudgill, 2000), and soil soluble P (e.g. Kuo and Jellum, 1987;Sharpley et al, 1995;Pote et al, 1999;Chen et al, 2003). Differences may be attributable to varying climates, soil types and land uses, but also the oft-used pre-analytical procedure of soil drying.…”

“…Kurz et al (2006) attributed the elevated runoff-water P o concentrations to a stimulation of microbial mineralisation following fertiliser-N application. Chen et al (2003) attributed spring maxima and summer minima waterextractable P (P w ) concentrations to a combination of fertiliser P application, biochemical P release and plant uptake, whilst Kuo and Jellum (1987) attributed a similar seasonal pattern to plant uptake and pH-sorption control. Other studies have found contrasting patterns in soil P solubility (Magid and Nielsen, 1992;Shand et al, 1994;McDowell and Trudgill, 2000) and runoff P (Kurz et al, 2005).…”

“…That is, accumulation through biomass incorporation and decomposition, followed by microbial immobilisation during the cool, wet conditions of autumn and winter. This is followed by early summer minima concentrations, reflecting rapid mineralisation and plant uptake (Chaneton et al, 1996;Kuo and Jellum, 1987;Tate et al, 1991b;Parfitt et al, 2005), and volatilisation of N, as temperatures increase -concurrent with low replenishment from biomass incorporation and decomposition. Olsen-extractable P decreases over 2002 correspond with typical quantities of P-uptake by grass growth in productive pastures.…”

“…Significant negative covariation observed between pH and P w DRP may reflect a desorption effect (e.g. Kuo and Jellum, 1987) or the simultaneous contribution of high mineralisation rates to both P w DRP accumulation and lower pH (increased acidity). It is uncertain whether summer drying in these soils was sufficient to cause soluble P release through aggregate disruption (e.g.…”