盐渍化草地根际土壤理化性质对降水改变和氮添加的响应

为揭示盐渍化草地根际效应及其对降水改变和氮添加的响应，对增水、减水和氮添加及其交互处理下晋北盐渍化草地根际和非根际土壤理化性质进行分析。研究发现：与对照相比，减水及减水+氮添加显著提高了土壤交换性Na⁺含量，氮添加提高了非根际土壤208.1%的硝态氮和105.3%的无机氮含量（P<0.05）；增减降水与氮添加交互对根际和非根际土壤理化性质均无显著影响；根际土壤pH值比非根际低0.25个单位，铵态氮、硝态氮、有机酸、氨基酸、全碳和全氮含量分别比非根际高412.0%，81.4%，37.5%，22.4%，37.3%和43.6%（P<0.05）；主成分分析发现根际和非根际土壤理化性质对水、氮交互处理的响应具有明显差异。表明盐渍化草地植物具有较强的根际效应，但其对增加降水及水、氮交互的响应不敏感，结果可为预测未来降水变化和大气氮沉降增加情境下盐渍化草地根际效应和土壤理化性质变化提供理论依据。

Response of Rhizosphere Soil Properties to Changed Precipitation and Nitrogen Addition in a Salinized Grassland

To reveal the soil rhizosphere effect and its response to changed precipitation and nitrogen (N) addition, we analyzed the rhizosphere and non-rhizosphere soil properties in a salinized grassland under six treatments including increasing precipitation by 50%, decreasing precipitation by 50%, N addition (10 g N·m^-2·a^-1), increasing precipitation by 50% plus N addition, decreasing precipitation by 50% plus N addition. The results showed that decreasing precipitation by 50% and decreasing precipitation by 50% plus N addition significantly increased the concentration of exchangeable Na⁺ in rhizosphere and non-rhizosphere soil (compared to control), respectively. The N addition increased nitrate and inorganic N concentrations in non-rhizosphere soil by 208.1% and 105.3%, respectively. There has been no interaction found between changed precipitation and nitrogen addition on soil properties in rhizosphere and non-rhizosphere soil. The pH of rhizosphere soil was significantly lower than that of non-rhizosphere soil by 0.25 units, and the concentrations of ammonium, nitrate, organic acids, amino acids, total carbon, and total N in rhizosphere soil were significantly higher than those of non-rhizosphere soil by 412.0%, 81.4%, 37.5%, 22.4%, 37.3%, and 43.6%, respectively.Through principal component analysis, it was found that there were significant differences in the response of rhizosphere and non-rhizosphere soil properties to changed precipitation and N addition. The results showed that plants in salinized grassland had a strong rhizosphere effect, but they were not sensitive to increased precipitation and interaction between changed precipitation and N addition. The results can provide a theoretical basis for predicting the rhizosphere effect and soil properties of salinized grassland under the scenario of future precipitation change and atmospheric nitrogen deposition increase.