ION EXCHANGE RESIN MEMBRANE (IERM): A NEW APPROACH OF IN SITU EXTRACTION OF PLANT AVAILABLE NUTRIENTS IN SOIL

We tested the suitability of ion exchange resin membrane (IERM) for in situ extraction of plant available nutrients in soil in both laboratory and field by comparison with several conventional chemical extraction methods. We also tested some factors that could affect nutrient accumulation on IERM to optimize the performance of IERM. The method, named as plant root simulators (PRS), was developed involving burial of IREM in soil, followed by a deionized water and dilute HC1 wash of IREM. More than 400 soil samples from across Western Canada were tested in three consecutive years of laboratory study. The plant availability of nitrate, phosphate, potassium and sulfate as predicted by IERM burial was significantly correlated with the plant availability predicted by conventional chemical extraction methods. Through the repeated growth chamber experiments during the three years, the ability of the IERM burial extaction to predict differences in availability of N, P and K to canola was similar to conventional soil extractions, but for S the IERM burial appeared to be better predictor of observed differences in plant uptake. The nitrate in situ extraction in field reflects the nutrient difference along with landscape and management. Direct butial of IERM in soil may be considered as a new approach to simultaneously and universally determine the nutrient status in soils.