Plants uptake of nutrients

Besides validating the occurrence of ion exchange, the experimental results of Waley and Thompson also established the preference of soil toward ammonium and potassium over calcium—a phenomenon that helped explain how ion exchange plays a key role in plants uptake of nutrients from soils. In principle, the ion exchangers present in soil with varying sele-ctivities toward different ions opened a new avenue to separate dissolved species by a simple filtration process. 

Since it is probably the case that the relationship between the available level of each trace element in the soil and its actual uptake by each species of plant is unique, it is clear that evidence based on experiments covering different kinds of plants grown at different available levels in the soil of common contaminants, is necessary before any conclusions can be drawn about the probable effects of trace-element contamination of soils. The relationship between the uptake by any species of plant and the available level of any trace element in the soil will also be modified by soil conditions and temperature, and there may also be varietal effects within species on uptake. Information on plant uptake of nutrients is usually obtained by carrying out pot experiments under experimental conditions which are rather different from those operating in the field. 

---