保水剂施用量对杨树苗土壤物理性状与微生物活性的影响

目的]探讨保水剂不同施用量对杨树土壤物理性状与微生物活性的作用效果,为中国杨树人工林节水高产实践模式提供理论依据与技术参考。方法]研究CK(常规灌量)、CL(60%常规灌量配施10g保水剂)、CM(60%常规灌量配施30g保水剂)和CH(60%常规灌量配施50g保水剂)4个处理对杨树苗土壤物理性状、水稳性团粒结构、微生物数量、微生物呼吸和代谢熵的影响。结果]同CK相比,CM处理显著降低了土壤容重,并明显提高了非毛管孔隙度,其中土壤容重分别较CK,CL和CH处理显著下降13.71%,5.31%和7.76%;还明显促进了土壤大团聚体(0.25mm团粒)的形成。同时,CM处理明显增加了土壤微生物总量和微生物量碳、氮含量,并显著增强了土壤微生物呼吸作用,其微生物呼吸速率分别比CK,CL和CH处理提高30.77%,11.84%和7.59%。此外,CM处理还降低了代谢熵,分别较CK,CL和CH处理下降4.81%,8.29%和9.74%。结论]适宜的节水灌溉措施(60%常规灌量与30g保水剂组合)有助于改善杨树苗土壤的物理环境,并增强微生物活性。

Effects of Application Amount of Super-absorbent Polymer on Soil Physical Characteristics and Microbial Activity Under Poplar Seedlings

Objective] The effects of different application amounts of super-absorbent polymer(SAP) on soil physical characteristics and microbial activity under growing poplar were researched to provide theoretical basis and technical reference for high-yield and water-saving practice modes in Chinese poplar plantation.Methods] Four treatments, including CK(conventional irrigation), CL(60% conventional irrigation quantity co-applied with 10 g SAP), CM(60% conventional irrigation quantity co-applied with 30 g SAP) and CH(60% conventional irrigation quantity co-applied with 50 g SAP) were set. Their effects on soil physical properties, water stability of crumb structure, microbial populations, microbial respiration and metabolic quotient under poplar seedlings grew in pots were determined.Results] The CM treatment significantly reduced soil bulk density and obviously increased non-capillary porosity. The soil bulk densities decreased in 13.71%, 5.31% and 7.76% as compared with those of CK, CL and CH, respectively. The formation of soil large aggregate(>0.25 mm size) was also promoted by the CM treatment. Moreover, the CM treatment observably increased total microbial populations and the contents of microbial biomass carbon and microbial biomass nitrogen. And CM treatment significantly enhanced microbial respiration, having 30.77%, 11.84% and 7.59% increases in microbial respiration rate in comparison with the ones of CK, CL and CH, respectively. In addition, the metabolic quotient was reduced by the CM treatment, having 4.81%, 8.29% and 9.74% decreases as compared with the ones of CK, CL and CH, respectively.Conclusion] As a result, the proper water-saving irrigation measure(60% conventional irrigation quantity co-applied with 30 g SAP) is beneficial to improve soil physical environment and enhance soil microbial activity under poplar seedlings.