Gl. Kerven et al., RELEASE CHARACTERISTICS OF ION-EXCHANGE RESINS AS BUFFERS IN LOW IONIC-STRENGTH NUTRIENT SOLUTIONS, Plant and soil, 156, 1993, pp. 239-242
The use of synthetic ion-exchange resins as buffers of nutrient ions i
s a potential mechanism for the control of ion concentrations in nutri
ent solutions. In this study equilibrium constants for two cation exch
ange resins and three anion exchange resins were determined at 25 degr
ees C in low ionic strength systems. The measured constants were used
to successfully predict the resin combinations required to achieve des
ired solution equilibrium concentrations. The effectiveness of these r
esins in buffering solution ion concentrations was evaluated by examin
ing their release characteristics in circulating systems from which al
iquots of solution were withdrawn and replaced with deionised water to
;simulate plant uptake. Buffering of NO3 and SO4 concentrations was ef
fective when manual control of one anion was imposed. The cation resin
s were ineffective in buffering the concentrations of Ca and Mg with a
tendency for the resins to retain most of the Ca and Mg in adsorbed f
orm.