紫外分光光度法测定农田土壤微生物生物量氮可行性初探

采用氯仿熏蒸浸提-紫外分光光度法和消化法比较测定了田间定位试验不同施肥处理土壤、添加植物残体土壤、添加葡萄糖土壤的微生物生物量碳、氮(SMBC,SMBN)。结果表明,当土壤微生物生物量氮含量较高时(>20 mg kg-1),采用分光光度法与消化法测定的SMBN具有显著正相关关系(P<0.05),但当SMBN量较低时(<20 mg kg-1)时,分光光度法测定与消化法测定的SMBN没有显著相关性。当土壤中添加麦秸和玉米秸时,土壤浸提液颜色较深(黄色),不适合采用分光光度法测定SMBN。因此,熏蒸提取–分光光度法测定SMBN,仅适于土壤浸提液无色透明、且SMBN含量较高的土壤。

Rapid Estimation of Microbial Biomass Nitrogen in Agricultural Soils by Ultraviolet Spectrophotometry Method

Soil microbial biomass nitrogen(SMBN) with different fertilization in long-term field,soil added with plant,soil added with glucose was determined by ultraviolet spectrophotometry and digestion method in the paper.The results showed that when SMBN content was larger than 20 mg kg-1,there was a significant correlation between SMBN by ultraviolet spectrophotometry method and digestion method;while SMBN content was less than 20 mg kg-1,the correlation was not obvious.In the experiment that the soil was added with wheat straw and maize stalk,the K2SO4 extracts became yellow,leading to no obvious correlation.As a result,ultraviolet spectrophotometry method was verified when K2SO4 extract was clarifying and colorless,and SMBN content was high.