冷季型绿肥对锥栗园土壤生化性质及微生物群落的影响

Effects of cold-season green manure on soil biochemical properties and the microbial community in a Castanea henryi orchard,China

为评价锥栗园生草法相比传统清耕法和施用化学除草剂法,果园土壤质量的绿肥恢复效益,本研究以福建典型的红壤丘陵山区锥栗园为研究对象,采用随机区组设计,将供试样地均分为面积0.3~0.5 hm2的若干试验小区,全园清除自然杂草后,设置撒播鼠茅草(Mode_(1))、黑麦草(Mode_(2))、光叶紫花苕(Mode_(3))3种生草处理,并以施用草甘膦(CK_(1))和清耕(CK_(2))处理为对照,每种处理3个重复,2年后,分析3种冷季型绿肥、清耕及施用草甘膦对锥栗园土壤理化性质、酶活性、微生物群落等指标的影响。结果表明:1)相较于清耕处理和喷施草甘膦处理,3种生草处理土壤碱解氮、有效磷、速效钾含量有明显提升,其中鼠茅草处理最高,分别为74.14、156.87和234.76 mg·kg^(-1);黑麦草处理土壤孔隙度最高,为56.03%;鼠茅草和黑麦草处理土壤蔗糖酶活性提升明显,分别为32.29和26.87 U·g^(-1)。2)5种处理土壤共有优势细菌类群主要为放线菌门、变形菌门、绿弯菌门和酸杆菌门,相对丰度分别为24.9%~28.9%、20.9%~28.8%、13.7%~18.6%和10.8%~12.9%,共有优势真菌类群主要为子囊菌门和担子菌门,相对丰度分别为37.4%~73.7%和15.3%~54.4%。3)相较于清耕处理,3种生草处理细菌群落Chao1指数和Shannon指数均有所提升,真菌群落有所下降。4)相较于清耕处理和喷施草甘膦处理,3种生草处理土壤变形菌门、拟杆菌门和厚壁菌门细菌相对丰度均有所下降,绿弯菌门和浮酶菌门细菌则有所增加,生草促使锥栗园土壤细菌群落由快速生长型向缓慢生长型转变。5)5种处理细菌群落和真菌群落非计量多维尺度转换排序(NMDS)表明,土壤真菌群落分异程度高于细菌群落。6)相关分析(CA)和冗余分析(RDA)表明,生草处理通过改变土壤蔗糖酶、过氧化氢酶活性和碱解氮含量,喷施草甘膦处理通过改变土壤碳氮比,清耕处理通过限制土壤自然含水率改变真菌相关优势类群。综上,锥栗园短期人工生草对土壤理化性质和酶活性有一定程度的改善作用,生草处理与清耕处理和喷施草甘膦处理均会形成特异土壤真菌群落。

This research evaluated the benefits of green manure for soil quality recovery,compared with traditional clear tillage and chemical herbicide application methods,in a Castanea henryi orchard in the typical red soil hill region of Fujian. A randomized block design was adopted,with each block having an area of 0. 3-0. 5 ha. The experiment site was cleared of natural weeds,then two grass species(Vulpia myuros,Mode_(1);Lolium perenne,Mode_(2))and a legume species(Vicia villosa,Mode_(3))were trialed as green manure crops,and compared with glyphosate(CK_(1))and clear tillage treatments(CK_(2)),with three replicates of each. After 2 years,the physical and chemical properties of soils in the three green mature and the two CK treatments in the C. henryi orchard were analyzed. It was found that:1) Compared with the clear tillage and glyphosate spraying treatments,the contents of alkali-hydrolyzable nitrogen,available phosphorus and available potassium in soils of Mode_(1),Mode_(2) and Mode_(3) green manure crops were significantly increased,and the Mode_(1) observe values was the highest,which ware 74. 14,156. 87 and 234. 76 mg·kg^(-1),respectively. The soil porosity of the Mode2 treatment was the highest,at 56. 03%. The sucrase activities in soil of the Mode_(1) and Mode_(2) were significantly increased,with values of 32. 29 and 26. 87 U·g^(-1),respectively. 2)The dominant bacterial groups shared by soils of all five treatments were Actinobacteria,Proteobacteria,Chloroflexi and Acidobacteria,with relative abundances of 24. 9%-28. 9%,20. 9%-28. 8%,13. 7%-18. 6% and 10. 8%-12. 9%,respectively. The dominant fungal groups shared by the five treated soils were mainly Ascomycetes and Basidiomycetes. 3)Compared with the clear tillage treatment,the Chao1 index and Shannon index of the bacterial community in the three green mature treatments were increased,while the fungal presence was decreased. 4)Compared with clear tillage and glyphosate spraying,the relative abundance of Proteobacteria,Bacteroides and Presence of Firmicutes in the soil of the three green manure treatments was decreased,while presence of bacteria of the phyla Chloroflexi and Planctomycetes was increased. The green manure crops promoted the transformation of the soil bacterial community from fast growth to slow growth. 5) Non-metric multidimensional scaling analysis of bacterial and fungal communities in the five treatments showed that the degree of differentiation of the soil fungal community was higher than that of the bacterial community. 6)Correlation analysis and redundancy analysis showed that the green manure crops increased soil invertase and catalase activities and alkali-hydrolyzable nitrogen content;the glyphosate treatment increased soil carbon:nitrogen ratio,and the clear tillage treatment changed fungi-related dominant groups by reducing soil water content. In summary,short-term green manure plantings in C. henryi orchards improved soil physical and chemical properties and enzyme activities to various degrees. Green manure,clear tillage and glyphosate treatments each resulted in a unique soil fungal community.