Effect of Organic Acids and Protons on Release of Non-Exchangeable NH＋ in Flooded Paddy Soils
摘要
In a model experiment, which imitated the rhizosphere of rice, the effect of organic acids (oxalic acid, citric acid) and protons on the release of non-exchangeable NH4^+ and the resin adsorption of N was studied in a paddy soil, typical for Zhejiang Province, China. Oxalic and citric acids under low pH conditions, in combination with proton secretion, favored the mobilization of NH4^+ ions and increased resin adsorption of N. The release of non-exchangeable NH4^+ was associated with less formation of iron oxides. These could coat clay minerals and thus hinder the diffusion of NH4^+ ions out of the interlayer. Protons enhanced the release of NH4^+, and then they could enter the wedge zones of the clay minerals and displace non-exchangeable NH4^+ ions.