Effects of iron plaque on surface electrochemical properties of rice roots and adsorption and absorption of NH₄⁺ and K⁺, but increased the adsorption of phosphate by the roots were investigated through hydroponic experiments. It was found that the iron plaque formed on rice roots reduced cation exchangeable capacity of the roots and made zeta potential on the roots less negative compared with control, suggesting that the number of negative charges on rice roots became less due to the formation of iron plaque. Iron plaque also inhibited the adsorption of NH₄⁺, K⁺ and phosphate by rice roots. Results of 6-h cultivation experiments showed that iron plaque lowered the uptake rate of NH₄⁺, k⁺ and phosphate by rice by 21.1%, 42.7% and 59.1%, respectively, as compared with control. In conclusion, functioning as physical and chemical barrier or temporary repository, iron plaque inhibit short-term uptake of macronutrient elements, like N, P and K, by rice plants.