| The maximum amount of nutrients adsorbed, stable time to extract the nutrients needed in alluvial soil, the effect of soil moisture on nutrient extracted by resin membrane were studied using domestic and imported ion exchange resin membranes in room simulated condition. The result indicates, the ion adsorption curves of different resin membranes are very similar within 1, 2, 5, 8 and 12 h of adsorption time, although the adsorption amount is quite different. The maximum adsorption amount of domestic resin membrane is always larger than that of imported resin membrane when calculation is based on the area of membrane. The ratio of ion adsorbed by domestic resin membrane with that adsorbed by imported resin membrane is as following: NH4+-N, 1: 2.6; K+, 1: 3.8; P, 1: 20.4. The adsorption process can be well fitted by logarithm curve with different burying periods. The adsorption process of phosphate and nitrate by domestic resin can be divided into two periods: the first one is contacting exchange process which is finished in a very short period; the second one is ion diffusion process which proceeds several hours. The amount of ion adsorbed in the second process is affected by the rate of ion diffusion and the desorption of ion from soil particles. The effect of soil moisture on the nutrient extracted is different among different nutrients, with P and K highly affected and NH4+-N and NO3~N less affected. It is well known that diffusion plays an important role in the movement of P and K in soil solution, as a result, soil moisture has a significant influence on the adsorption of P and K by resin membrane. The result also indicates, there are still some problems in the determination of nitrogen using ion exchange resin membrane.
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