
%0 Journal Article
%A Powell, HKJ 
%A Hawke, DJ 
%T Free aluminum and aluminum complexation capacity of natural organic-matter in acidic forest soil solutions from Canterbury, New Zealand
%J Soil Research
%D 1995/08/01
%V 33
%N 4
%P 611-620
%K Aluminum;Soil Solution;Complexation Capacity;Canterbury;Flow Injection Analysis;
%R https://doi.org/10.1071/SR9950611
%U https://www.publish.csiro.au/paper/SR9950611 
%X Measurement of soil solution Al complexation capacity (Al-CC) at pH 4 . 7 by using a simple colorimetric flow injection analysis technique is described. Forest soils from four sites (Canterbury, N.Z.) of contrasting rainfall (from 655 mm to about 3000 mm) were examined. Results showed a strong inverse correlation (r2 = 0.992) between pH and log(soil solution Al-CC) in high-organic surface horizons, indicating that high rainfall generates both acidity and Al complexing ligands. Soil Al-CC (µmol Al kg-1 dry soil) was highest (199 µmol kg-1) in the Ca horizon from the wettest site, and lowest (2.2 µ mol kg-1) in the B horizon of one of the intermediate rainfall sites. Soil solution Al-CC was proportional (r2 = 0.94) to the organic matter content of all horizons, as estimated by absorbance at 250 nm. The slope of the regression against A250, expressed as fulvic acid equivalent, gave a higher Al-CC (1360 ± 210 mmol kg-1) than measured for soil fulvic acid alone (550 mmol kg-1), indicating a contribution from non-absorbing complexants. The pH dependence of log(free [Al]) (slope -0.38 ± 0.17) implicates colloidal and/or solid phase organics in the control of soluble Al in organic horizons. 
