葡萄糖存在下选择性抑菌剂对土壤氮素转化的影响

采用2种氮源并分别加入选择性微生物抑制剂进行室内培养，通过测定样品中NH₄⁺-N和NO₃^--N及土壤中氨基葡萄糖和胞壁酸含量，研究土壤微生物氮素固持时间特征及其相对贡献.结果表明，加入青链霉素明显地降低了NH₄⁺-N的转化速率，且影响远大于真菌抑制剂放线菌酮；氨基葡萄糖和胞壁酸的相对比例急剧增加，而后趋于平衡；加入放线菌酮后NO₃-N转化速率持续下降，氨基葡萄糖的合成受到抑制，但加入细菌抑制剂青链霉素对其转化无显著影响.培养初期，细菌在葡萄糖存在下能快速固持NH₄⁺-N和NO₃^--N，并以NH₄⁺-N为首选氮源；培养后期，氮转化主要为真菌所推动，且真菌对NO₃^--N的利用能力显著大于细菌.

Effects of specific microbial biocides on N transformation in soil with glucose amendment

In an incubation test of soil with glucose amendment,two kinds of nitrogenous fertilizer and three kinds of specific microbial biocides were applied,and the contents of soil NH_4~+-N,NO~-_3-N,glucosamine and muramic acid were measured to differentiate the relative contribution and timing characteristics of soil microbes in nitrogen immobilization.The results showed that penicillin and streptomycin decreased the transformation rate of NH_4~+-N markedly,with more significant effects than actidione.The amount ratio of glucosamine to muramic acid after applying penicillin and streptomycin rapidly increased first,and tended to equilibrium then.With the application of actidione,the transformation rate of NO_3~--N decreased continuously,and the synthesis of glucosamine was inhibited,while penicillin and streptomycin had no significant effects on them.At the early stage of incubation,bacteria could rapidly immobilize both NH_4~+-N and NO_3~--N,with NH_4~+-N preferred,while at the later stage of incubation,fungi were the dominant contributor to nitrogen transformation,and had much stronger ability of utilizing NO_3~--N than bacteria.