A SAND-ZEOLITE CULTURE SYSTEM FOR SIMULATING PLANT ACQUISITION OF POTASSIUM FROM SOILS

A sand-zeolite culture system simulating plant acquisition of K from soils has been developed. The system, a mixture of synthetic zeolite IE-96 and coarse-sand, provides K concentrations comparable to soils depending on the K concentration ratios of solutions loaded onto the cation-exchange sites of the zeolite and the ionic strengths of the nutrient solutions supplied during the period of plant growth. Tomato (Lycopersicon esculentum Mill.) strain 203, PI 124163, was used in this study. An increase in the amount of the loaded zeolite per culture pot did not shift solution phase K activity ratios (ARk) of the culture system but did result in a linear increase of plant dry matter accumulation, indicating that K bioavailability is diffusion-limited in the sand-zeolite culture system as in soils. © 1990 Kluwer Academic Publishers.