微生物菌剂对烟草连作土壤理化性质及土壤胞外酶酶活性的影响

  目的  为研究微生物菌剂对不同连作年限植烟土壤的影响。  方法  以不同连作年限植烟土壤为研究对象，研究微生物菌剂对植烟土壤理化性质、胞外酶活性以及烟草农艺性状的影响，旨在为缓解烟草连作障碍提供参考。  结果  （1）未添加微生物菌剂的土壤随连作年限增加，土壤养分含量有机碳（SOC）、全氮（TN）、有效磷（AVP）、铵态氮（NH₄+-N）和硝态氮(NO₃--N）呈降低趋势，土壤pH值呈下降趋势，介于5.0~6.4；土壤胞外酶过氧化物酶（PER）、酸性磷酸酶（ACP）、纤维二糖水解酶（CBH）活性不同程度下降；同时烟草长势变弱，株高、根、茎、叶鲜重和相同叶位叶片干重、鲜重、叶长和叶宽均呈降低，且均在连作8年达最低。（2）添加微生物菌剂后，土壤有机碳、全氮、有效磷、硝态氮和铵态氮含量呈上升趋势，土壤pH值呈上升趋势，介于6.0~7.1；土壤胞外酶活性得到不同程度改善。  结论  3种外源微生物均能改善土壤胞外酶活性，提高碳循环和氮循环能力，增加土壤养分，促进烤烟生长，缓解连作障碍。 

Effects of microbial agents on physicochemical and extracellular enzyme activities of tobacco continuous cropping soil

  Objective  The effects of microbial agents on tobacco soil in different continuous cropping years were studied.  Methods  The effects of microbial agents on physical and chemical properties, extracellular enzyme activities and agronomic characters of tobacco soil with different years of continuous cropping were studied.  Results  (1) Without microbial agents, the contents of SOC, TN, AVP, NH+ 4-N and NO- 3-N decreased with the increase of continuous cropping years, and soil pH value decreased from 5.0 to 6.4. The activities of soil extracellular enzyme peroxidase (PER), acid phosphatase (ACP) and fibrinose hydrolase (CBH) decreased in different degrees. At the same time, the plant height, fresh weight of root, stem and leaf organs, dry weight, fresh weight of leaves, leaf length and leaf width all decreased, and reached the lowest levels after continuous cropping for 8 years. (2) After microbial agent treatment, the contents of soil organic carbon, total nitrogen, available phosphorus, nitrate nitrogen and ammonium nitrogen showed an increasing trend, and the soil pH value was in the range of 6.0 to 7.1; The extracellular enzyme activities of soil were improved in different degrees.  Conclusion  All the three microbial agents could improve extracellular enzyme activity, carbon and nitrogen cycling ability, increase nutrient content in soil, promote tobacco growth, and alleviate continuous cropping obstacle.