A solid‐phase buffer technique to maintain low concentrations of phosphate in nutrient solutions

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Abstract
An inexpensive and mechanically simple technique was developed to maintain realistically low P concentrations in nutrient solutions using a solid-phase buffer. Phosphate is adsorbed on alumina in a PVC [polyvinyl chloride] column, and the resulting alumina-P is desorbed against nutrient solution circulated through the column. Kinetics of P adsorption and desorption indicate that the solid-phase-P has rapidly and slowly desorbing components and that buffering capacity is limited by desorption from the solid phase. The technique has been used to maintain P concentrations as low as 0.4 mmol m-3 for 26 days in experiments with maize (Zea mays L.), and in solution cultures with prune (Prunus domestica L.) trees. Effects of P supply on P accumulation and P transport are discussed.