苏打盐碱土对氮转化的影响

Effects of Saline-Alkali Soil on Nitrogen Transformations

以苏打盐碱土中的主要成分NaHCO3作为主要影响因素,通过室内培养方法,研究不同苏打盐碱化条件对氮的吸附、矿化、硝化及反硝化作用的影响。结果表明,在不同NaHCO3质量浓度影响下:NH4+-N吸附符合Langmuir吸附等温式;矿化模型符合一阶动力学方程,随着NaHCO3质量浓度的增大,潜在矿化势(M0)和矿化速率常数(km)分别由358.48mg/kg和0.088d-1降低到337.08mg/kg和0.059d-1;硝化作用符合'S'形曲线模型,随着NaHCO3质量浓度的增大,最大速率(kmax)由22.56mg/(kg.d)降低到16.68mg/(kg.d);反硝化作用符合零阶动力学方程,但NaHCO3与Na2CO3混合质量浓度变化对反硝化速率常数(kd)影响不显著。随着NaHCO3质量浓度的增大,苏打盐碱土中NH4+-N吸附、有机氮矿化和硝化作用均受到抑制。

The main component NaHCO3 was considered as the main factor in Soda saline-alkali soil in order to study the effects of different soda salinization levels on nitrogen adsorption, mineralization, nitrification and denitrification by using laboratory incubation. The results showed that in the experimental conditions with the different NaHCO3 concentrations, the NH＋ --N adsorptions obeyed Langmuir linear adsorption isotherm, while, the N mineralization could be described by the first-order kinetic equation. With the increasing of NaHCOa concentration, the N mineralization potential （M0） and mineralization rate constant （km） decreased from 358. 48 mg/kg and 0. 088 d^-1 to 337.08 mg/kg and 0. 059 d^-1, respectively, and the nitrification could be described by ＂S＂ curve model, the maximal rate of nitrification （kmax） decreased from 22. 56 to 16. 68 mg/（kg · d）; the denitrification obeyed zero-order kinetic equation, and there was no significant effect of mixed concentrations variation of NaHCOa and Na2CO3 on the denitrification rate constant （kd）. NH4＋ -N adsorption, organic nitrogen mineralization and nitrification were inhibited with NaHCO3 concentrations increasing in soda saline-alkali soil.