喀斯特边远农区正安县植烟土壤重金属含量及其特征

在喀斯特边远农区典型植烟县采取代表性植烟土壤样品66个,研究县级尺度下植烟土壤重金属含量及其特征。结果表明,Pb,Hg,Cr 3种重金属含量全部符合国家土壤环境质量二级标准,As含量符合国家土壤环境质量二级标准的样点数高达98.5%,4种重金属环境状况良好,无污染。Cd含量符合国家土壤环境质量二级标准样点数占69.7%,且有10.1%的样点含量高于国家土壤环境质量三级标准,部分植烟土壤已受到染污。3种不同植烟土壤类型重金属含量差异较大,石灰土Cd,Hg,As平均含量最高（分别为0.51 m g/kg,0.173 m g/kg,15.45m g/kg）,水稻土Pb,Cr平均含量最高（分别为66.13 m g/kg,55.63 m g/kg）,黄壤居于中间水平。土壤重金属含量与土壤质地密切相关,与土壤粒径具有一定的相关性,粘粒与镉、砷极显著正相关（r=0.333^＊＊,r=0.345^＊＊）,与汞显著正相关（r=0.289^＊）,砂粒与汞、砷显著负相关（r=-0.286^＊,r=-0.245^＊）。喀斯特边远农区植烟土壤重金属环境状况总体良好,但应重视Cd的控制管理。     

化学调控剂对土壤和莴笋中Hg,Cd,Pb含量的影响研究

通过盆栽试验和解吸试验，研究了石灰，腐殖酸、硫化钠、亚硒酸钠等化学调控剂对土壤重金属Hg，CA，Pb含量及在植物体内积累的影响机理。研究表明：适用荆量的石灰、腐殖酸能显著抑制莴笋对Hg的吸收，增加土壤中Hg的含量；而Na2S则能显著抑制莴笋对Pb的吸收，增加土壤中Pb的含量。从农产品安全要求出发。在试验条件下。抑制土壤Hg、Cd、Pb进入莴笋体内的最佳化学物质及剂量分别为：石灰施用量为10．0g／kg、腐殖酸施用量为2．67g／kg，亚硒酸钠施用量为2．19mg／kg时，抑制Hg进入莴笋体内的效果最好；石灰施用量为10．0g／kg时抑制Cd进入莴笋体内的效果最好；石灰、腐殖酸，硫化钠施用量分别为10．0g／kg。2．67g／kg和0．47mg／kg时抑制Pb进入莴笋体内的效果最好。     

长期不同施肥下红壤活性有机质与碳库管理指数变化

对长期不同施肥5a和10a后红壤活性有机质进行了测定，结果表明，耕作10a不施肥或仅施化肥（CK、N、NP、NK、PK、NPK）的土壤活性有机质（LOM）及碳库管理指数（CMI）都明显下降，最大下降（CK）分别为40．5％和48．1；而有机肥或有机肥化肥配合施用（M、MNPK、1．5MNPK），LOM和CMI则显著升高，最大升高（1．5MNPK）分别为183％和195；秸秆还田（SNPK）处理LOM和CMI先下降后增加，5a分别下降25．2％和31，10a又分别上升17．9％和13。说明化肥主要提高非活性有机质，有机肥则显著改善土壤有机质质量，秸秆还田对提高红壤有机质质量比有机肥慢。用33mmol L^-1、167mmol L^-1、333mmol L^-1KMnO4测定的三种活性有机质（本文分别称其为高活性有机质HLOM、中活性有机质MLOM和活性有机质LOM）的含量依次增加，分别占总有机质的5．6％、9．6％和14．5％。三种活性有机质之间呈显著或极显著相关，HLOM与MLOM相关系数为0．478^＊，HLOM与LOM为0．592^＊＊，MLOM与LOM为0．716^＊＊。作物产量只与MLOM和LOM极显著相关，相关系数分别为0．821^＊＊和0．602^＊＊，而和总有机质没有显著的相关性。同时，LOM及CMI与土壤阳离子交换量、交换性钾、交换性钙、盐基总量、微量元素等呈显著或极显著正相关，但总有机质与上述土壤化学指标相关性差。这些结果暗示LOM和CMI比总有机质更能客观反映土壤肥力和土壤质量的变化情况，应该成为描述土壤质量和评价土壤管理的良好指标。     

化学添加剂对土壤和莴笋中重金属残留量的影响试验

针对重庆市蔬菜重金属污染现状,选取Hg、Cd、Pb为优先控制的目的重金属,通过盆栽试验,研究了石灰、腐殖酸、硫化钠等化学添加剂对莴笋吸收土壤重金属的效应及土壤重金属的残留机理。研究表明：适当剂量的石灰、腐殖酸能显著抑制莴笋对Hg的吸收,增加土壤中Hg的含量;而Na₂S则能显著抑制莴笋对Pb的吸收,增加土壤中Pb的含量。从农产品安全要求出发,在试验条件下,抑制Hg、Cd、Pb进入莴笋体内的最佳化学物质及剂量分别为：石灰施用量为10.0 g/kg、腐殖酸施用量为2.67 g/kg时,抑制Hg进入莴笋体内的效果最好;石灰施用量为10.0 g/kg时抑制Cd进入莴笋体内的效果最好;石灰、腐殖酸、硫化钠施用量分别为10.0、2.67 g/kg和0.47 mg/kg时抑制Pb进入莴笋体内的效果最好。     

强烈人为作用下城镇周围汞的空间变异及其积累迁移规律

研究土壤中汞(Hg)元素积累的空间变异和迁移转化规律对土壤利用、环境评价和污染修复具有重要参考价值。本研究选择经济发展迅速的苏南某地为研究区域,对土壤、水稻和大气降尘中的Hg进行了详细分析。结果表明,该区域土壤全汞平均含量达1 345μg kg-1,有效汞(HC l-Hg)平均含量51μg kg-1,水稻Hg平均含量20μg kg-1,大气Hg沉降量为5.13 g km-230 d-1。土壤和水稻高含量Hg主要积聚于城镇周边,随着与城镇距离的增加其含量逐渐减少。大气Hg沉降量在空间上变化不大。进入土壤中的Hg主要在土壤表层0~20 cm范围内富集,但直至60 cm深处依然存在积累现象,整个剖面土壤活性态汞和半活性态汞含量占全汞的比例变化不大。研究区土壤出现了明显Hg积累,导致水稻Hg吸收明显增加,不少样点超过了国家土壤环境质量二级标准(300μg kg-1)和国家食品污染物限量标准(20μg kg-1),可能对环境和人体健康产生危害。较低的大气Hg沉降量和土壤积累的Hg已与土壤条件达到平衡的事实表明,目前Hg的积累已明显减少。今后应采取措施修复污染土壤或者通过改变作物种类来减少土壤Hg含量或抑制作物对Hg的吸收,达到环境治理的目的。     

土壤残渣有机质与固定态铵之间的关系

采集了全国不同类型的土壤40个,分析了土壤全氮、有机质、固定态铵、剩余有机质（KOBr处理后的土壤有机质）、残渣有机质（KOBr-HF处理后的土壤有机质）含量.结果表明,以2∶1型粘粒矿物为主土壤的残渣有机质含量与固定态铵含量之间呈极显著正相关（r=0.831^＊＊）,晶格之间存在的有机质（即残渣有机质与剩余有机质之差值）含量则与固定态铵含量之间也呈极显著正相关（r=0.832^＊＊）,而以1∶1型粘粒矿物为主土壤的残渣有机质含量和晶格有机质含量与固定态铵含量不相关;土壤剩余有机质、残渣有机质的含量分别为2.59 g kg^-1、3.70 g kg^-1,分别占土壤有机质的10%和16%.土壤残渣C/N比（平均值为16.69）明显高于原土壤（平均值为5.37）.     

福建沙县东溪流域土地退化特征初步研究

综合运用^137Cs,土壤磁测等新技术手段,结合土壤结构水稳性,CEC等部分土壤理化指标,对闽西沙县东溪流献殷勤 地不同部位的土地退化特征进行初步的定量研究,结果表明：（1）土壤中^137Cs含量与坡度呈很强的对数关系（R＝－0．83）,表明土地退化随坡度的增加而加剧,（2）土壤表层磁化率富集系数与坡度呈较强的对数关系（R＝－0．63）,表明土地退化随坡度的增加而加剧;（3）不同地貌部位以及不同的土地利用类型之间,其土壤部分理化指标,在不同的显性水平上,呈现一定的退化特征。     

芜湖燃煤电厂周边土壤中砷汞的分布特征研究

探讨了芜湖燃煤电厂周边随距电厂水平方向、垂直剖面土壤中砷汞总量及形态分布特征,并分析了土壤中砷汞与理化性质之间的相关性。结果表明:土壤中As、Hg的变幅分别为3.821～19.264mg/kg,0.025～1.696mg/kg,平均含量分别为6.671mg/kg和0.212mg/kg。As、Hg含量总体分布特征为:距电厂1km处最大,距电厂1km距离内次之,距电厂1km以外,随距离增大而减小,其中汞随距离衰减明显。土壤汞含量在东南-西北(SE-NW)主导风向上明显大于东北-西南(NE-SW)非主导风向,而As含量在不同风向上基本无差异;土壤汞含量随剖面深度的增加明显减少,而砷在剖面上的分布规律不明显。土壤中砷主要以硫化物态和残渣态存在,而汞以残渣态和腐殖酸结合态为主。表层土中As、Hg与理化性质之间存在不同程度的相关性。     

贵州水城煤矸石风化土壤-农作物系统中汞分布规律研究

通过冷原子荧光方法测定了贵州水城汪家寨煤矿和那罗煤矿不同年限的煤矸石风化土壤及农作物中总Hg含量和甲基汞含量,并采用BCR连续提取法分析了煤矸石风化土壤中汞的不同赋存形态,系统地对此矿区煤矸石风化土壤-农作物系统中汞的分布规律及其环境效应进行了研究。结果表明,煤矸石风化土壤样中汞含量范围在0.07～1.06 mg.kg-1之间,和pH值存在显著负相关关系（r=-0.68,P〈0.01）。风化年限较长的煤矸石土壤汞浓度接近对照点自然土壤汞含量,而在风化年限较短的煤矸石风化土壤中,大部分样品汞浓度超过了国家Ⅱ类土壤环境标准,不宜在上面种植食用的农作物。煤矸石风化土壤中甲基汞含量在0.52～2.68μg.kg-1之间,和总汞存在显著正相关关系（r=0.65,P〈0.05）。煤矸石风化土壤中汞主要以有机/硫化态和残渣态存在,风化年限较短的煤矸石山土壤中酸交换态汞浓度及比例都明显高于老煤矸石山。虽然汪家寨煤矿风化年限较短的煤矸石山土壤存在着较高的汞含量,但其上种植的马铃薯、玉米、菜豆的汞含量均没有超过国家标准食品中Hg限量值,然而高于风化年限较长的煤矸石山中同类植株的汞含量。     

钝化剂对污染土壤汞钝化效果及辣椒吸收汞的影响

  目的  探究三种钝化剂（碳酸钙、氧化钙和硅酸钙）对污染土壤汞（Hg）的钝化效果及辣椒吸收汞的影响。  方法  以贵州万山汞矿区汞污染耕地土壤为研究对象,以碳酸钙、氧化钙和硅酸钙为钝化材料,采用盆栽试验方法,研究三种钝化剂对土壤pH、汞化学形态和有效汞变化的影响,同时考查在外源钝化剂的驱动下,辣椒植株汞含量和汞转运系数的变化特征。  结果  碳酸钙、氧化钙和硅酸钙的施用分别使土壤pH提高0.74 ~ 2.28、2.11 ~ 5.24和1.79 ~ 2.62个单位,土壤活性态汞含量显著降低,残渣态汞含量显著升高,有效汞含量显著降低,且施加0.1%的氧化钙对土壤有效汞降低效果最佳。三种钝化剂均可使辣椒根、茎和果实汞含量降低,且随着钝化剂施加量的增加而降低,其中氧化钙对辣椒根部汞含量降低效果最好。三种钝化剂对辣椒植株各组织汞转运的影响存在差异,施用三种钝化剂均可促进辣椒根中汞向茎和叶中转运,但抑制辣椒根中汞向果实转运。  结论  三种钝化剂均可作为汞污染土壤的钝化修复材料,且均显著抑制辣椒吸收汞,其中,0.1%的氧化钙对土壤汞的钝化修复效果更好,值得推广应用。     

Phosphorus Uptake by Young Citrus Trees in Low-P Soil Depends on Rootstock Varieties and Nutrient Management

Because low-phosphorus (P) availability limits citrus growth, rootstocks with a relatively high capacity for P uptake are desirable. An experiment was conducted with trees on Cleopatra mandarin (CM) and Rangpur lime (RL). Treatments consisted of P rates (20, 40, and 80 mg kg^?1 of soil) applied in soil layers of 0–0.30 m and/or 0.31–0.60 m, besides an unfertilized control. The P fertilization increased root and shoot growth, and P nutrition was improved as indicated by greater leaf P concentration, P uptake, and P root uptake efficiency (PUE). The P applied in both soil layers improved shoot growth, P uptake, and PUE. Trees on RL took up 23–126% more P and had root systems with greater growth and PUE compared to those on CM. Thus, P uptake by citrus trees in low-P soils can be improved by augmenting the depth of fertilizer application and the use of more adapted rootstocks.     

RELATIONSHIP BETWEEN SUGAR MAPLE DECLINE AND CORRESPONDING CHEMICAL CHANGES IN THE STEM TISSUE

Wood cores were taken at breast height of mature sugar maple (Acer Saccharum Marsh.) trees of approximately the same age from four sites in Ontario, Canada differing in soil characteristics and general tree health. The soils of two of the sites were acidic (podzols), while the soils of the other two sites were calcareous (brunisols). Selected elemental analyses using Neutron Activation Analysis were conducted on the soils and the xylem wood of the sugar maple trees, and the results were compared relative to tree health. Aluminum in stem xylem was found to be significantly higher in declining trees (mean 7.7 ppm) relative to the healthy trees (mean 4.0) from the acidic sites, where aluminum was freely available in the soil. Soil extractable aluminum was also significantly higher in the soil adjacent to the declining trees (mean 5.10) compared to the healthy trees (mean 3.20). These results show that xylem aluminum contents reflect the increased availability of aluminum in acidifying soils and provide additional evidence that dendrochemistry may be used as a proxy environmental monitoring tool.     

Soil Fertility,Mineral Nitrogen,and Microbial Biomass in Upland Soils of the Central Amazon under Different Plant Covers

Amazon is the largest state in Brazil and majority of the state is covered by the largest tropical rainforest of the world. Most soils of the Amazon region soils are acidic and infertile. When the Amazon forest land is cleared for agricultural use by burning the vegetation, the efficient nutrient recycling mechanisms are disrupted. However, nutrient contents in the deforested burn land increased temporarily. The objective of this study was to evaluate the soil fertility, mineral nitrogen (N), and microbial activity of carbon (C), N, and phosphorus (P) resulting from the replacement of the primary forest with pasture (Brachiaria brizantha) and commercial plantations of rubber (Hevea spp.), cupuaçu (Theobroma grandiflorum), and citrus trees (Citrus sinensis) cultivated in Xanthic Ferralsol and secondary forest under Acrisols Dystric Nitosols. The results showed that ammonium-N predominates in the 0- to 10-cm soil depth in both primary forest and areas with secondary forest, citrus plantation, and pasture. There was no increase in soil fertility with management of the cultivated areas under the secondary forest, but in the pasture there was a significant increase in the stock of organic C and total N and high C/N ratios, the inverse of what occurred with the C of the microbial biomass. The primary forest had the greatest values of C and P of the microbial biomass and the lowest metabolic quotient. Of the successions studied, the rubber trees were the plant cover with the smallest changes in terms of quality of the organic matter in the soil.     

Treated municipal wastewater for citrus irrigation 1

Treated, reclaimed municipal wastewater was evaluated on citrus trees in central Florida for over six years. The effects of irrigation with reclaimed wastewater on soil water content, soil chemical analysis, leaf mineral status, and fruit quality were compared with those of irrigation with well water. Irrigation with reclaimed water increased mineral residues in the soil profile, altered leaf mineral concentration and fruit quality, and promoted better tree performance and more weed growth relative to irrigation with well water. Higher accumulation of nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) in soils irrigated with reclaimed water were not significantly reflected in leaf mineral status. Although leaf sodium (Na), chloride (Cl), and boron (B) concentrations were noticeably higher in reclaimed water treatments than in those of well water, they are still far below the toxicity levels. This highly treated wastewater in central Florida has been found to be a very safe and good option for increasing water supplies, but not a significant source of plant nutrients to citrus trees.     

重庆柑橘园钙素营养研究

研究重庆柑橘园的钙素营养现状,为合理管理柑橘园钙素营养提供科学依据。通过对重庆市218个柑橘园土壤及叶片的采样分析和调查研究,结果表明,重庆市柑橘园土壤钙含量丰富,平均为3316.7 mg/kg,其中49.5%的土壤有效钙含量较高（＞3000 mg/kg）,缺钙的土壤（1000 mg/kg）仅占 17.9%;但是柑橘叶片钙含量不足或缺乏（30 g/kg）的柑橘园占38.3%,叶片钙含量过高(70 g/kg)的仅占0.3%;叶片钙含量不足的样本数明显高于缺钙土壤;土壤钙与柑橘叶片钙含量的关系因土壤钙含量的不同而存在差异,当土壤有效钙含量低 (1000 mg/kg)时,叶片钙含量也低(30 g/kg),叶片钙含量随土壤有效钙含量的增加而升高,二者呈极显著正相关 y=0.0151 x +16.459 (r =0.608**, n=39, r 0.01=0.408);当土壤有效钙含量呈高量或过量时,二者的相关关系不显著,叶片缺乏和过量现象并存。缺钙土壤和钙含量高的土壤上都可能出现叶片缺钙现象,在管理柑橘园钙素营养时,应综合分析影响钙素营养的各种因素,选择适宜的钙肥种类、施钙方式和时期,结合土壤的供钙能力、柑橘种类及砧木、营养元素之间的平衡等,制定出合理的管理模式。     

亚硝化球菌属(Nitrososphaera)可能是酸性土壤硝化作用的重要驱动者

选择初始pH相近的两个酸性土壤(JX-3和JX-7)样品进行培养试验,探讨了氨氧化古菌(ammonia-oxidizing archaea,AOA)和氨氧化细菌(ammonia-oxidizing bacteria,AOB)在酸性土壤硝化过程中所发挥的作用。结果显示,经过50 d的培养,JX-7样品硝化速率显著高于JX-3,且明显降低土壤pH。培养后,两个土壤样品AOB丰度均增加,但样品间没有显著差异;JX-7土壤AOA丰度显著增加,而JX-3无显著变化。两个土壤样品AOA群落组成本身存在分异,但对于同一样品培养前后均无显著分异;AOB群落组成在两土壤间没有分异,但培养前后分别有分异。培养后,JX-7样品中AOA优势属Nitrososphaera和某些未知微生物的个别OTUs绝对丰度显著增加,而两样品AOB中Nitrosospira属的一些OTUs的绝对丰度均显著增加。因此,所研究的酸性土壤样品中AOA是硝化作用的主要贡献者,而且AOA主要通过提高Nitrososphaera属中个别OTUs的丰度,而不是整个群落来调控硝化作用。     

八宝景天–柑橘间作降低柑橘根际土壤镉含量以减少对镉的吸收

  【目的】  超富集植物与经济作物间作是实现重金属污染农田边生产边修复的有效措施。为此，研究八宝景天 (Hylotelephium spectabile) 和柑橘间作对柑橘重金属吸收累积的影响，为柑橘生产提供安全、经济有效的栽培措施。  【方法】  以早熟和晚熟柑橘、八宝景天为试材进行盆栽试验，以全Cd含量为0.92 mg/kg的污染土壤和0.06 mg/kg的清洁土壤为供试土壤。分别设置早熟和晚熟柑橘单作、八宝景天单作、早熟和晚熟柑橘–八宝景天间作和柑橘–八宝景天限制性间作，共7个处理，限制性间作采用半透膜根际袋将八宝景天和柑橘根系分开。在植株生长74天 (7月) 和218天 (12月)时采样，调查植株生物量和Cd含量，分别测定根际土壤全Cd和有效态Cd含量。  【结果】  与柑橘单作相比，与八宝景天间作柑橘的叶片Cd含量降低了26.7%，与清洁土壤种植的柑橘叶片Cd含量 (0.011 mg/kg) 相近。间作条件下，柑橘根际土壤中全Cd含量由0.92 mg/kg降低至0.75 mg/kg，有效态Cd含量由单作处理的0.82 mg/kg降低至0.78 mg/kg，低于柑橘单作处理；柑橘–八宝景天间作柑橘根际土壤中全Cd的减少量是柑橘–八宝景天限制性间作柑橘根际土壤全Cd减少量 (6.52%) 的2.83倍。柑橘–八宝景天间作中八宝景天对土壤Cd的年提取量、年去除率分别达1.40 mg/pot、3.34%，与其单作 (1.50 mg/pot、3.73%) 相比，去除效率降低了10.6%，其主要原因是间作降低了八宝景天的生物量。  【结论】  尽管柑橘–八宝景天间作影响八宝景天对镉的去除效率，但显著降低了柑橘根际全Cd和有效态Cd含量，进而将柑橘叶片Cd含量降低到与清洁土壤下近似的水平，实现了边修复边安全生产的目标，因此，柑橘–八宝景天间作可作为中低度Cd污染农田土壤修复的重要生物措施。     

Effects of trench planting and soil chiselling on soil properties and citrus production in hilly ultisols of China

Trench planting and soil chiselling are special techniques of soil utilization and reclamation for citrus production in the hilly red soil region of China. Serious erosion, acidity, compactness, low fertility, and seasonal drought are major problems in this region. These problems in the red soil (i.e., ultisol in US taxonomy system) limit plant production, especially that of deeply rooting plants. Trench planting was aimed at improving the entire rooting space for the citrus tree growth before the citrus saplings are transplanted to the red soil. Several years later, in order to provide more rooting space for the mature citrus trees, another soil chiselling trench was made beside the planting trench. Materials, including lime, fertilizer and organic manure, were mixed in both planting and chiselling trenches, rapidly increasing soil nutrients in the entire rooting depth and improving soil structure and other soil physical conditions. The yield observations showed that the citrus trees bore fruit one year earlier in the trench planted orchard than in the conventional orchard, and that the citrus yield increased more than three times in eight years after the citrus saplings were transplanted.     

Dolomite Phosphate Rock–Based Slow-Release Fertilizer for Agriculture and Landscapes

Most soils in Florida are very sandy, and water-soluble fertilizers (WSF) are subjected to leaching loss. Alternate fertilization is a promising practice to reduce such loss. Dolomite phosphate rock (DPR), which contains calcium, magnesium, and phosphorus, is potentially useful for agricultural production and landscaping plants. In this study, DPR fertilizers were developed from mixing of DPR material and N-viro soil. A typical agricultural soil (Alfisol) in Florida was used for greenhouse studies, and ryegrass and citrus seedlings were tested. The DPR fertilizers appeared superior to WSF for the growth of ryegrass based on dry-matter yield and nutrient concentrations in plant; however, it was not evident in citrus seedlings. DPR fertilizers were effective in raising pH (by 3 units) and electrical conductivity of acidic sandy soils and increasing soil organic matter, total nutrients, and available nutrients. The concentrations of copper, lead, and zinc in the plant tissues were less than toxicity limits.     

柑橘生长与土壤养分及微生物群落的关系研究

  目的  探讨影响柑橘生长的相关因子,为柑橘生长的科学管理提供依据。  方法  在相同管理措施条件且树木无病害的情况下,采集四种长势（长势良好为Ⅰ等级,长势一般为Ⅱ等级,长势较差为Ⅲ等级,矮小无产为Ⅳ等级）的柑橘根区土壤,分析其土壤养分有效性、酶活性以及细菌群落结构。  结果  Ⅳ等级柑橘根区土壤中全氮和速效钾含量显著低于其他等级的柑橘根区土壤（P < 0.05）,Ⅰ等级柑橘根区土壤中有效钙、镁、硼含量均显著高于其他三个等级柑橘根区土壤（P < 0.05）, Ⅳ等级柑橘根区土壤中的铜含量显著低于其他等级柑橘根区土壤（P < 0.05）。Ⅰ等级柑橘根区土壤中β-葡萄糖苷酶和纤维二糖水解酶活性显著低于其他等级的橘树根区土壤。Ⅰ等级柑橘根区土壤中绿弯菌门（Chloroflexi）和假单胞菌属（Pseudomonas）相对丰度显著高于Ⅳ等级柑橘根区土壤。冗余分析结果表明,Ⅳ等级柑橘树根区土壤细菌群落明显区别于Ⅰ ~ Ⅲ等级柑橘树,速效钾与有效钙是影响细菌群落的重要因子。  结论  不同长势柑橘树土壤中有效钾、全氮、有效钙、镁、硼等养分含量具有显著差异,从而导致柑橘树生长状况出现差异。其次中微量元素的缺乏也提醒农户在果园日常施肥中,除注意大量元素的施用之外,还应重视中微量元素的肥料施用。本研究尚未发现土壤酶活性与柑橘长势情况显著相关,但发现微生物群落对柑橘长势产生影响,各级柑橘根区土壤微生物群落之间差异较大、优势菌为芽孢杆菌属（Bacillus）、假单胞菌属（Pseudomonas）,由此推测土壤微生物群落与土壤养分联系紧密,进而影响柑橘的生长发育。