Relationship between soil properties and phosphate saturation parameters - A transect study in northern Belgium

We investigated the relations between soil properties and the variability at held-scale of soil P sorption capacity (PSC) and degree of P saturation (DPS), and the relationship between DPS and P concentrations in soil solution. Soil samples of 0-30 cm, 30-60 cm and 60-90 cm depths were collected every 10 meters on a transect of a total length of 539 meters in the northeastern part of the province Antwerp, Belgium. Oxalate extractable iron, aluminium and phosphate content (Fe-ox, Al-ox and P-ox) were determined, and the PSC and DPS calculated Phosphate concentrations measured in 100 mM KCl extracts of the soil samples of the 0-30 cm layer were closely related to the DPS of the samples. The spatial distribution of Fe-ox was rather homogeneous, except in the vicinity of a ''discontinuity'' such as a drainage ditch, where much higher Fe-ox values were measured. The spatial variability of the Al-ox parameter was closely related to the spatial variability of the amount of oxalate extractable carbon and total carbon, but this was not the case for Fe-ox. Detailed textural information for the transect did not correlate to PSC parameters at this scale; pH(KCL) or p(H2O) showed little variability on the transect scale. Variograms of the PSC parameters were obtained for three separate data-sets: one for the total transect, one for the total transect but excluding ditch data, and for part of the transect situated within one field (the first 410 m of the total transect).