氮添加对盐渍化草地根际土壤理化性质的影响

Effects of nitrogen addition on rhizosphere soil properties in a salinized grassland

为探究氮输入和根际效应对盐渍化草地土壤理化性质的影响,对8个水平氮添加处理下(0、1、2、4、8、16、24和32 g N·m^(-2)·a^(-1))晋北盐渍化草地根际和非根际土壤理化性质进行研究。结果表明:氮添加显著降低根际土壤pH,显著增加根际和非根际土壤Ca^(2+)、NO_(3)^(-)-N和无机氮含量;随氮添加量的增加,根际和非根际土壤Ca^(2+)、NO_(3)^(-)-N、无机氮含量以及根际土壤全氮含量呈逐渐升高的趋势,而根际土壤Na^(+)、K^(+)、Mg^(2+)、NH_(4)^(+)-N和氨基酸含量以及非根际土壤全氮含量呈先升高后降低的趋势。主成分分析表明,根际土壤理化性质对低氮(≤8 g·m^(-2)·a^(-1))和高氮添加(>8 g·m^(-2)·a^(-1))的响应具有明显差异。根际土壤pH、有机酸和氨基酸含量分别比非根际土壤低0.71、44.3%和9.8%,而K^(+)、Ca^(2+)、Mg^(2+)、NH_(4)^(+)-N、无机氮、全碳和全氮含量分别比非根际土壤高51.0%、47.6%、20.8%、215.5%、139.3%、31.7%和65.3%,表明根际效应对盐渍化草地土壤理化性质的影响大于氮输入的影响。

We explored the impacts of nitrogen(N)inputs and the rhizosphere effect on the properties of rhizosphere and bulk soils in a salinized grassland in Northern Shanxi under N addition rates of 0,1,2,4,8,16,24 and 32 g N·m^(-2)·a^(-1).The results showed that N addition significantly decreased soil pH,but significantly increased Ca^(2+),NO_(3)^(-)-N and inorganic nitrogen contents in rhizosphere and bulk soil.With the increases of N addition rates,the contents of Ca^(2+),NO_(3)^(-)-N,inorganic nitrogen in rhizosphere and bulk soils and total nitrogen in rhizosphere soil increased gradually,whereas the contents of Na^(+),K^(+),Mg^(2+),NH_(4)^(+)-N and amino acid in rhizosphere soil,and total nitrogen in bulk soil first increased and then decreased.Results of the principal component analysis showed that the responses of soil properties to low(≤8 g·m^(-2)·a^(-1))and high nitrogen addition rates(>8 g·m^(-2)·a^(-1))were significantly different.Compared with bulk soil,soil pH,the contents of organic acids and amino acids in rhizosphere soil were significantly lower by 0.71 units,44.3%and 9.8%,respectively,while the contents of K^(+),Ca^(2+),Mg^(2+),NH_(4)^(+)-N,inorganic nitrogen,total carbon and total nitrogen in rhizosphere soil were significantly higher by 51.0%,47.6%,20.8%,215.5%,139.3%,31.7%and 65.3%,respectively.These results indicated that rhizosphere effect on soil properties was stronger than that of nitrogen addition.