引用本文:刘 星,吴华勇,杨 升,卢 翔,王金旺,陈秋夏.海涂围垦区不同耐盐树种根际土壤团聚体形成及养分分布特征[J].土壤学报,2020,57(5):1270-1279. DOI:10.11766/trxb201908240243
LIU Xing,WU Huayong,YANG Sheng,LU Xiang,WANG Jinwang,CHEN Qiuxia.Formation of Soil Aggregates and Distribution of Soil Nutrients in Rhizosphere of Salt-tolerant Trees in Coastal Polder Reclamation[J].Acta Pedologica Sinica,2020,57(5):1270-1279. DOI:10.11766/trxb201908240243
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海涂围垦区不同耐盐树种根际土壤团聚体形成及养分分布特征
刘 星1, 吴华勇2, 杨 升1, 卢 翔1, 王金旺1, 陈秋夏1
1.浙江省亚热带作物研究所林业与生态研究室;2.土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所)
摘要:
以温州宋埠围垦区的滨海潮滩盐土为研究对象,种植泌盐乔木——柽柳(Tamarix chinensis)、拒盐灌木——厚叶石斑木(Rhaphiolepis umbellata)和拒盐乔木——白榆(Ulmus pumila),分析植树2a后各树种根际土壤团聚体形成及养分分布特征。与裸地相比,柽柳、厚叶石斑木和白榆根际土壤pH分别下降0.14、0.43、0.39,电导率分别下降80%、70%、72%。裸地土壤粒径均小于0.053 mm,各树种根际土壤形成的微团聚体(0.25~0.053 mm)占土壤总质量的5.0%~5.9%,大团聚体(2~0.25 mm)占比小于1%。相比粉+黏团聚体(<0.053 mm),微团聚体中有机碳和游离铁含量分别呈现上升和下降趋势,表明微团聚体形成可能是一个脱铁富碳过程。与裸地相比,各树种根际土壤全氮和碱解氮显著增加,而速效钾含量显著下降。各树种根际土壤全氮和碱解氮含量以白榆最高(分别为1.20 g·kg-1和42.6 mg·kg-1),且微团聚体中全氮和碱解氮显著高于粉+黏团聚体。综上所述,植树2 a后,各树种根际土壤盐碱度显著下降,且形成团聚体,表明柽柳、厚叶石斑木和白榆适宜作为浙南围垦区的改良树种。其中,白榆根际形成的团聚体数量多,富集碳、氮养分效果好,为首选树种。
关键词:  盐土改良  耐盐植物  根际  土壤团聚体  土壤养分  白榆
基金项目:浙江省农业科学院青年科技人才培养项目 ( 2018R26R08E02)、温州市林业四新推广示范项目(ZJSF-DY20180728WZC)和国家重点研发计划项目课题(2018YFC1801806)资助
Formation of Soil Aggregates and Distribution of Soil Nutrients in Rhizosphere of Salt-tolerant Trees in Coastal Polder Reclamation
LIU Xing1, WU Huayong2, YANG Sheng1, LU Xiang1, WANG Jinwang1, CHEN Qiuxia1
1.Department of Forestry and Ecology, Institute of Subtropical Crops of Zhejiang Province;2.State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences
Abstract:
【Objective】This study is oriented to explore effects of salt-tolerant trees different in species ameliorating coastal saline-alkali soils for screening trees suitable for establishment of shelterbelts and ecological greening in coastal areas.【Method】Three different species of trees, i.e. Tamarix chinensis (salt-secreting arbor), Rhaphiolepis umbellata (salt-rejecting shrub), and Ulmus pumila (salt-rejecting arbor) were planted in a tract of mudflat of saline-alkali soil in the Songbu Polder on the coast of Wenzhou. Two years after the trees were established, soil samples were collected from the rhizospheres of the trees for analysis of particle size distribution of soil aggregates and key physicochemical properties of the aggregates by particle size, including soil organic carbon (SOC), dithionite-extractable Fe (hydro)oxides (DCB-Fe), total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and readily available potassium (AK).【Result】Compared with the soil in the bare-land (CK), the soil in the rhizosphere of T. chinensis, R. umbellata, and U. pumila was 0.14, 0.43 and 0.39 lower in pH and 80%, 70% and 72% lower in electrical conductivity (EC), respectively. The soil particle size of CK was <0.053 mm, while soil aggregates were formed in the rhizosphere of the trees with the content of soil micro-aggregates (0.25-0.053 mm) being 5.0%-5.9%, and the content of macro-aggregates (2-0.25 mm) being much lower, accounting for less than 1% of the total of soil aggregates. The content of SOC increased significantly in the rhizosphere soils, but the content of DCB-Fe decreased significantly (P<0.05), especially in micro-aggregates, which suggests that soil aggregation was coupled with Fe removal and C accumulation. Soil nutrients, including TN, AN and AP were elevated in content within the rhizospheres of all three species. The content of TN (1.20 g·kg-1) and AN (42.6 mg·kg-1) in the rhizosphere soil of U. pumila was 15.4% and 23.8%, respectively, higher than those in CK. The content of AN (85.8 mg·kg-1) in micro-aggregates was the highest among the aggregate fractions in the rhizosphere of U. pumila . Interestingly, much higher AP contents in silt-clay aggregates (16.4-19.0 mg·kg-1) than that in micro-aggregates (10.4-11.4 mg·kg-1) were detected in the T. chinensis and R. umbellata plantations, whereas no difference was observed in U. pumila rhizosphere soil (P>0.05). After establishment of the trees, AK decreased significantly or by 4.5%-11.5% in rhizosphere soils as compared that in CK (P<0.05). For all the rhizosphere soils, the content of AK varied in the range of 115.0-216.3 mg·kg-1 in micro-aggregates, which was significantly lower than those in silt-clay aggregates (303.0-342.0 mg·kg-1).【Conclusion】 Cultivations of the salt-tolerant trees can ameliorate saline-alkali soils by reducing salinity and improving soil structure and soil fertility. T. chinensis, R. umbellata, and U. pumila could all be used as effective pioneer trees for mudflat reclamation projects. Among these species, U. pumila appeared to be the most effective thanks to its high capability of carbon and nitrogen enrichment in the rhizosphere soil.
Key words:  Saline-alkali soil amelioration  Salt-tolerant plants  Rhizosphere  Soil aggregate  Soil nutrients  Ulmus pumila