生物炭对土地整治区土壤微生物调控效应

  目的  为巩固土地整治成效, 提高土壤地力, 探讨生物炭对土地整治区土壤微生物调节效应的影响。  方法  通过大田试验, 添加不同水平梯度生物炭(0、7.5、15、30、45 t/hm2), 分析施用后对土壤微生物学指标的影响。  结果  (1) 当用量>7.5 t/hm2时, 生物炭平均降低土壤微生物生物量碳氮比(MBC/MBN)70.22%, 土壤微生物商81.11%;(2)适量生物炭可提高土壤微生物的生物多样性, 细菌和真菌的OTUs分别在生物炭用量为20~30 t/hm2和10~30 t/hm2时达到峰值, 但当用量≥30 t/hm2时, 生物炭对OTUs具有降低作用; (3)生物炭可影响细菌和真菌的群落结构, 对细菌变形菌门和放线菌门的相对丰度分别有着降低和提高的作用, 对真菌子囊菌门则具有先降低后升高的作用; (4)生物炭对硝化细菌和反硝化细菌的相对丰度具有降低作用, 但对固氮菌却有提高作用, 有利于土壤固氮; (5)适量生物炭可降低土壤可能致病菌属的相对丰度, 但高剂量施用将增大烟叶生产感病风险。  结论  适量生物炭对土地整治区土壤微生物性状具有改良效果, 将用量控制在15 t/hm2左右为宜。 

Control effect of biochar on soil microorganism in land consolidation region

  Objective  In order to improve soil fertility of land consolidation region, a long term field experiment was designed to study the control effect of biochar on soil microorganism in land consolidation region.  Methods  This experiment consisting of 5 treatments, i.e.treatment without biochar addition named as CK (0 t/hm2) and treatments with 4 different levels (7.5, 15, 30 and 45 t/hm2) of biochar addition, was performed to study the effect of biochar addition on the soil microbiology index.  Results  (1) When application rate of biochar was above 7.5 t/hm2, soil microbial biomass C/N ratio and microbial quotient were significantly decreased by 70.22% and 81.11%, respectively.(2) The biodiversity of soil microorganism could be increased by moderate application of biochar; the OTUs peaks of bacteria and fungi were reached when the biochar application rate were 20-30 t/hm2 and 10-30 t/hm2, respectively.However, the OTUs would be decreased when the biochar application was more than 30 t/hm2.(3) With the increase of biochar application rate, the relative abundance of Proteobɑcteriɑ was decreased and the relative abundance of Actinobɑcteriɑ increased, while the relative abundance of Ascomycotɑ was increased at first and then decreased.(4) The application of biochar reduced the relative abundance of nitrifying bacteria and denitrifying bacteria, while increased the relative abundance of azotobacter.Therefore, biochar was beneficial to soil nitrogen immobilization.(5) A moderate application of biochar reduced the relative abundance of possible pathogenic bacteria, whereas a high dosage of biochar would raise disease risk in tobacco production.  Conclusion  A moderate application of biochar could improve soil microbial characteristics in land consolidation region.The optimal application rate was about 15 t/hm2.