Mb. Turrion et al., Extraction of soil-available phosphate, nitrate, and sulphate ions using ion exchange membranes and determination by ion exchange chromatography, COMM SOIL S, 30(7-8), 1999, pp. 1137-1152
In recent years, ion exchange membranes (IEM) have been used successfully t
o determine the availability of soil nutrient elements for plants. In gener
al, the procedures proposed are applied to the determination of a single io
n, and in only a few of these studies, the selectivity of these IEM was con
sidered. Therefore, this work was conducted (a) to find the most suitable e
xtraction conditions for phosphate (H2PO4-), nitrate (NO3-), and sulfate (S
O42-) in soils by IEM and their subsequent determination by ion chromatogra
phy, (b) to test the effectiveness and selectivity of IEM, (c) to compare t
he results obtained by IEM with the common procedure for determining the av
ailability of the soil nutrient elements, and (d) to verify whether a relat
ion exits between the concentration of phosphorus (P) extracted by IEM and
the plant P requirement. The soil samples used for this study were Humic Ca
mbisols located in four forest plots under natural conditions and four plot
s fertilized with 100 kg P ha(-1) as triple superphosphate. The efficacy of
the IBM was high (85% for SO42-, and 92% for H2PO4- and NO3-). Statistical
ly significant correlations were obtained between the H2O4- extracted by IE
M and the H2PO4- obtained by the Bray P1 procedure (r(2)=0.936) and with th
e H2PO4- extracted using Saunders and Williams (1955) procedure(r(2)=0.370)
. The correlation obtained between the amount of NO3- extracted with IEM an
d that obtained using 2M potassium chloride (KCl) was also highly significa
nt (r(2)=0.828). The IEM extraction allowed to know in a single extraction
process and a single subsequent measurement by ion chromatography the conce
ntrations of soil available H2PO4-, NO3-, and SO42- ions, which are of grea
t plant nutrition interest. Phosphorus extractable with IEM yielded a close
relationship with biomass production and could be used for determining the
P requirement of these forest trees.