中文摘要：

以宁夏新垦的淡灰钙土为对象,研究了蚕豆/玉米间作系统不同施氮水平下土壤活性有机碳、氮的时空变异特征。结果表明：新垦淡灰钙土土壤微生物量碳、氮（SMBC、SMBN）及可溶性有机碳、氮（SOC、SON）等活性有机碳、氮含量较低;随着施氮量的增加土壤SMBC含量显著增加;玉米收获期土壤SMBC、SMBN含量显著高于蚕豆收获期;土壤SMBC、SMBN含量空间变异为：蚕豆行间（F-F）含量最高,玉米行（M）、玉米行间（M-M）最低。与不施氮相比,施氮显著提高了蚕豆收获期土壤SOC、SON含量,而玉米收获期各施氮水平间土壤SOC和SON含量无明显差异;土壤SOC、SON的空间变异为：玉米行间〉蚕豆行间、蚕豆行（F）、蚕豆与玉米行间（F-M）〉玉米行。玉米收获期土壤SMBC及SMBN含量的显著增加,说明土壤微生物对矿质氮的固持对于新垦土壤肥力的提高具有重要作用。

英文摘要：

A field experiment was conducted to study the temporal and spatial changes of active organic C and N in the newly cultivated light sierozem soil under faba bean/maize intercropping system at Hong Shipu in Ningxia.The results showed that the contents of soil microbial biomass C and N（SMBC,SMBN） and soil soluble organic C and N（SOC,SON） in this newly cultivated soil were low in comparison with long-term cultivated soil.Soil microbial biomass C increased with the addition of N fertilizer.The contents of SMBC and SMBN in soil after harvesting maize were significantly higher than harvesting faba bean.The contents of SMBC and SMBN were the highest between lines of faba bean,followed by on lines of maize,and between lines of maize.Application of N fertilizers significantly increased SOC and SON contents at faba bean harvest time in comparison to the treatment without addition of N fertilizer;and had no effect on SOC and SON contents at maize harvest time.The contents of soluble organic C and N in soil were the highest between lines of maize,followed by between lines of faba bean,and on line of faba bean,and between lines of maize and faba bean,and the lowest was in on line of maize.Significant increase of SMBC and SMBN in soil at maize harvest phase suggested that immobilization of mineral N by soil microbial community could improve the fertility of the newly cultivated soil.