呼伦贝尔草地植物群落与土壤化学计量学特征沿经度梯度变化

植物化学计量学特征在大尺度上主要受纬度和经度两个因素影响。纬度梯度上温度因子变化对植物化学计量特征的影响已有大量研究,但是关于经度梯度上降雨因子变化对植物化学计量特征影响的研究却较少。选取呼伦贝尔草原,研究经度梯度上植物化学计量特征和土壤养分指标的变化规律,从经度梯度和养分供给两方面分析植物群落化学计量特征的变化规律,研究结果如下:1)植物群落叶片C含量变化范围为440.76—452.72 mg/g,N含量变化范围为17.79—30.88 mg/g,P含量变化范围为1.31—1.71 mg/g;群落叶片C含量、C/N随经度升高显著增加;群落叶片N含量随经度升高显著下降;植物群落P含量也呈下降趋势,但是关系不显著;植物群落C、N和P元素总量随着经度升高而显著增加。2)0—10 cm土壤全碳、全氮、全磷、有机碳受降雨量变化和植物群落元素总量影响,随着经度梯度升高而增加;但土壤铵态氮、硝态氮在经度梯度上没有表现出规律性的变化趋势。3)土壤全碳、有机碳、全氮、全磷和速效磷与植物群落叶片C、N和P含量没有显著相关关系,但与植物群落C、N和P元素总量呈显著正相关关系。该区土壤有效磷含量(8.13 mg/kg)高于全球平均值(7.65 mg/kg),但植物群落叶片磷含量平均值(1.5 mg/g)低于全球平均值(1.77 mg/g)。通过研究结果推测:植物通过对气候条件的长期适应,群落水平C、N和P含量沿经度梯度形成一定的分布格局;降雨量影响植物群落元素积累的总量,从而与土壤养分含量呈显著正相关关系;植物叶片P含量低的原因并非是由于土壤中磷的供给不足所致,而是植物对环境长期适应形成的策略。     

贺兰山不同海拔植被下土壤微生物群落结构特征

为明确海拔变化对干旱区山地森林土壤微生物群落的影响,揭示环境因子改变后土壤微生物群落结构特征及影响因素。对贺兰山5个海拔梯度土壤理化性质进行测定,同时采用磷酸脂肪酸(PLFA)图谱法分析土壤微生物群落组成,通过主成分分析、冗余分析(RDA)探究土壤理化性质与土壤微生物群落相对丰度之间的相关关系。结果表明:土壤养分含量在不同海拔之间差异性显著(P<0.05),土壤有机碳和全氮含量随海拔的升高而升高,全磷含量随海拔升高先升高再降低再升高;土壤微生物量随海拔升高先升高后降低,土壤微生物的相对丰度在不同海拔之间存在差异(P<0.05);主成分分析表明,与第1主成分相关性较强的微生物类群为革兰氏阳性细菌(G~+)、革兰氏阴性细菌(G~-)和真菌;与第2主成分相关性较强的微生物类群为放线菌、原生动物和非特异性细菌。非特异性细菌和真菌与各土壤因子之间均有显著相关关系,而放线菌、G~+和G~-与各土壤因子相关性较弱,原生动物与土壤全磷含量的关系密切。海拔是影响特征微生物分布的重要因素,特征微生物的含量和相对丰度随海拔的升高先升高后降低,符合山地生态学中的"中部膨胀"理论。探明了贺兰山不同海...     

氮磷添加对内蒙古温带典型草原土壤微生物群落结构的影响

选取内蒙古温带典型草原,进行连续6a氮磷添加试验,采用土壤特征微生物PLFA生物标记技术,研究6个氮添加水平N0(0 kg N hm-2a-1)、N1(56 kg N hm-2a-1)、N2(112 kg N hm-2a-1)、N3(224 kg N hm-2a-1)、N4(392 kg N hm-2a-1)、N5(560 kg N hm-2a-1)和6个磷添加水平P0(0 kg P hm-2a-1)、P1(15.5 kg P hm-2a-1)、P2(31 kg P hm-2a-1)、P3(62 kg P hm-2a-1)、P4(93 kg P hm-2a-1)、P5(124 kg P hm-2a-1)对土壤特征微生物PLFA生物标记数量和土壤微生物群落结构的影响。结果表明:(1)随氮添加量增加,土壤微生物总磷脂脂肪酸(PLFA)含量和土壤细菌PLFA生物标记数量、放线菌PLFA生物标记数量呈上升趋势,土壤G+/G-呈增加趋势;各氮添加水平对土壤真菌PLFA生物标记数量无显著差异,随氮添加量增加,土壤真菌/细菌比降低。(2)随磷添加量增加,土壤总磷脂脂肪酸(PLFA)含量、土壤细菌PLFA生物标记数量、放线菌PLFA生物标记数量、真菌PLFA生物标记数量及真菌/细菌比值呈先上升后下降趋势,均以P3水平(62 kg P hm-2a-1)处理最高,说明适宜的磷添加对内蒙古温带典型草原土壤微生物繁殖和菌落结构有显著影响。     

滇中退化山地不同植被恢复下土壤碳氮磷储量与生态化学计量特征

植被恢复对土壤营养元素的存赋及其生态化学计量特征的影响广受关注,为了深入了解不同植被恢复类型下土壤碳、氮、磷储量与生态化学计量特征,选择滇中地区退化山地飒马场流域具有代表性的4种不同修复阶段的典型植被(荒坡灌草丛、云南松林、针阔混交林和次生常绿阔叶林)为研究对象,分析了不同植被类型下不同深度土壤中有机碳(SOC)、全氮(TN)、全磷(TP)储量和化学计量变化特征。结果表明,退化山地的植被恢复显著改变土壤碳氮磷储存能力和化学计量比,这种改变作用整体上随土壤深度增加而降低。其中,在0—60 cm土层上,SOC储量在次生常绿阔叶林最高,达123.41 t/hm~2,其次是针阔混交林(115.69 t/hm~2)和云南松林(93.08 t/hm~2),荒坡灌草丛(89.56 t/hm~2)最低;TN储量针阔混交林(4.91 t/hm~2)次生常绿阔叶林(4.58 t/hm~2)云南松林(4.43 t/hm~2)荒坡灌草丛(3.98 t/hm~2),4种植被类型间差异显著;TP储量云南松林最高(2.57 t/hm~2),次生常绿阔叶林(2.2 t/hm~2)最低;4种植被类型下土壤C/N介于15.77—30.18,C/P介于29.24—65.33,N/P介于1.28—2.68之间,在0—60 cm土层上均以次生常绿阔叶林最高。植被类型和土壤深度及其交互作用显著影响研究区的SOC、TN和TP储量和化学计量比。分析认为,退化山地不同植被类型对土壤碳氮磷储量和化学计量的影响过程复杂,修复演替进入到次生常绿阔叶林阶段土壤理化性质显著提升,该地区植被修复主要受到氮的限制。研究表征了滇中退化环境植被恢复过程中土壤主要元素变化特征,为揭示植被恢复与土壤生态功能演变关系提供数据支持。     

Ectomycorrhizas associated with a relict population of Dryas octopetala in the Burren, western Ireland. I. Distribution of ectomycorrhizas in relation to vegetation and soil characteristics

The distribution of ectomycorrhizas on Dryas octopetala L in grass heaths of the 450 km² karst region known as the Burren in Western Ireland was examined in relation to soil factors and vegetation type. Ectomycorrhizas were identified or characterised from 56 soil cores from 30 sites, and the occurrence of each ectomycorrhizal (EM) type was quantified by estimating the total length of mycorrhizal tips of each type. Soil organic matter, total nitrogen, extractable phosphorus, pH and depth were the soil factors determined. In total, 24 EM types were recorded. The EM community of Dryas roots was significantly more species-rich in one vegetation type—Hyperico-Dryadetum—than in others (Arctostaphylo-Dryadetum or Asperulo-Seslerietum). Multiple linear regression analyses indicated that soil organic matter and soil depth explained a significant portion of the variation in EM abundance, while soil organic matter and extractable phosphorus explained a significant portion of the variation in EM diversity. Canonical correspondence analysis showed that some individual EM types (e.g. Craterellus lutescens, Cenococcum geophilum, Tomentella sp., Boletus sp.) exhibited distinct soil preferences, most markedly in relation to soil organic matter, which, in this analysis, was the main significant soil variable distinguishing the three vegetation types.     

秸秆还田对设施番茄产量和土壤磷素的影响

进行温室玉米秸秆还田对番茄的增产效果以及对设施土壤磷素的影响研究。通过单因素试验,检测秸秆还田对微生物量磷和磷素淋溶的影响。与对照相比,添加秸秆可以显著提高土壤中全磷和有效磷的含量,以能显著提高土壤的磷活化系数,以秸秆30 000 kg/hm²、磷肥（过磷酸钙,P）200 kg/hm²（S3P3）的处理最高,有效降低土壤中全磷和有效磷向下迁移的能力。秸秆还田还可以增加土壤中微生物量磷含量,秸秆还田量和微生物量磷之间存在中等程度相关,并改变土壤中有效磷的比例,进而对植物生长产生一定的影响。结果表明,秸秆还田能够改变磷元素在土壤耕作层中的分布,提高土壤中微生物量磷和有效磷的含量,增加原土壤的磷活化系数,并显著减少磷素的淋溶量,为降低农业面源污染提供了部分解决途径。     

Direct evidence on participation of root hairs in phosphorus (32P) uptake from soil

Root hairs substantially extend root surface for ion uptake. Although many reports suggest a relationship between root hairs and phosphorus (P) uptake of plants, the role of root hairs in phosphorus uptake from soils is still debated. We measured uptake of phosphorus from soil directly via root hairs. Root hairs only were allowed to penetrate through a tightly stretched nylon screen (53 µm) glued to the bottom of a PVC tube. The penetrating root hairs grew for 2 and 4 days in soil labelled with radioisotope phosphorus (P) tracer ³²P (185 kBq g^-1 dry soil) filled in another PVC tube. Transparent plastic rings of thickness ranging from 0.25 mm to 2.0 mm were inserted between the two PVC tubes. This provided slit width for microscopic observations in situ, which confirmed that only root hairs were growing into the ³²P labelled soil. In some cases no rings were inserted (slit width = 0) where both root hairs and root surface were in contact with the labelled soil (total ³²P uptake). The uptake of³² P from soil via the root hairs only was quantified by measuring activity of ³²P in the plant shoot (³²P uptake only via root hairs).The results showed that when 70 percent of the root hairs grew into the labelled soil, they contributed to 63 percent of the total P uptake. With decreasing number of root hairs growing into the ³²P labelled soil, the quantity of ³²P in the plant shoot decreased. In this study, P uptake via root hairs was measured in a soil-based system, where root hairs were the only pathway of ³²P from soil to the plant shoot. Therefore, this study provides a strong evidence on the substantial participation of root hairs in uptake of phosphorus from soil.     

模拟氮沉降对荆条灌木“肥岛”土壤养分的影响

氮沉降的增加,可能会对土壤养分造成更为显著的影响,目前关于大气氮沉降对植物"肥岛"效应中土壤养分的影响鲜有报道。于河南省太行山南麓地区,以NH_4NO_3为供施氮源,按土层深度采集土样,以模拟氮沉降方法(3个水平,无氮CK、低氮2g N m~(-2)a~(-1)处理、中氮12g N m~(-2)a~(-1)处理和高氮24g N m~(-2)a~(-1)处理),分析了氮沉降对太行山荆条灌木(Vitex negundo L.var.)"肥岛"土壤中有机质、全氮和速效磷含量的影响。结果表明:灌木"肥岛"中全氮和速效磷含量,总体表现出随氮沉降量增长而增加的趋势;氮沉降显著增加了土壤表层有机质、氮、磷的含量;高氮沉降与CK相比引起的各土层间养分差异更显著;随着氮沉降水平的增加,冠幅内外和土层间养分差异增大,土壤养分的增长率随之加大;氮沉降在一定程度内加剧了"肥岛"的富集效应,且氮沉降量越大,这种富集效应越显著。这些研究结果可为研究灌木"肥岛"对外源氮的响应机制及保育作用提供参考。     

陕西榆林春玉米高产田土壤理化性状及根系分布

调查分析了陕西榆林2块19500 kg·hm^-2以上超高产春玉米田的产量构成、干物质分配和0～100 cm土层根系分布及土壤理化性状指标.结果表明：其种植密度为105000～123000株·hm^-2、成穗率97.7%～102.2%、千粒重320 g以上,果穗干物质积累量占整株干物质积累量的60.2%～65.5%.0～100 cm土壤平均容重为1.28～1.33 g·cm^-3,层间（每层20 cm）土壤容重、孔隙度和田间持水量均呈“M”型变化.玉米根系主要分布在0～60 cm,0～20 cm土层根系量占根系总量的64.8%～72.1%,20～60 cm土层根系量占根系总量的23.30%～28.17%.根系分布与土壤理化性状关系密切,0～20 cm土层玉米的根系量与土壤有机质、全氮和全磷含量呈显著正相关,20～60 cm土层根系量与土壤容重和田间持水量显著相关.因此,选择通透性和保水保肥能力良好的土壤,实行宽窄行双株密植栽培是获得玉米高产的关键.     

微地形对大西沟新疆野杏萌发层土壤因子的影响

野杏是新疆野果林的主要建群种和种质资源树种。野杏在种子萌发成苗期,幼苗的根系主要分布在0—15 cm土层中。为了阐明坡向、坡位、坡度和坡形等微地形因子对野杏种子萌发层土壤特征和养分分布的影响,在新疆伊犁州霍城县大西沟的封育野果林内(44°26′01.09″—44°26′17.12″N,80°46′27.49″—80°47′03.26″E)设置样地,测定0—15 cm土层的土壤砾石、酸碱值、有机质和全氮、全磷、全钾、水解性氮、有效磷和速效钾含量,分析各土壤因子和地形因子的关系。结果表明:(1)东北坡土壤养分含量较高,其土壤砾石含量、酸碱值、有机质、全磷、水解性氮和速效钾含量与东南坡、南坡皆存在显著差异(P0.05),阴坡的土壤有机质、全氮、有效磷和速效钾含量都高于阳坡,不同坡向的土壤特征和养分分布存在显著差异(P0.05);(2)不同坡位的土壤有机质、全氮、全磷和有效磷含量均表现为中坡位下坡位上坡位,土壤砾石、全钾和速效钾含量均呈现上坡位中坡位下坡位,全钾、全磷和有效磷含量在同坡位分布较均匀,不同坡位的土壤特征和土壤养分分布无显著差异(P0.05);(3)不同坡度下的土壤水解性氮和有效磷含量是缓坡中坡缓中坡陡坡,土壤砾石、酸碱值、全氮、水解性氮、有效磷和速效钾含量有显著差异(P0.05),陡坡土壤有机质、全氮、水解性氮和有效磷含量均低于其他坡度,而土壤砾石、土壤酸碱值和全钾在陡坡土层中含量最高,缓坡与缓中坡的土壤养分含量丰富,陡坡较为贫瘠,坡度对土壤特征和土壤养分分布有显著影响(P0.05);(4)不同坡形下的土壤砾石、全钾、水解性氮、有效磷和速效钾含量是凸形坡凹形坡直线坡,不同坡形下的土壤特征和土壤养分(除全钾和速效钾)均存在显著差异性(P0.05)。野果林地形因子对野杏萌发层土壤特征和土壤养分分布有显著影响,东北坡、中坡位、缓坡和凸形坡土壤养分含量较为丰富,是适宜野杏萌发的地形。研究结果可为探究影响野杏种子萌发和生长的气候与土壤水热等因子奠定良好基础。     

Active Iron in Plant Leaves

Tomato plants were grown with limited or luxury water supplyand given nitrogen either as the ammonium ion or the nitrateion. The ‘active’ iron fractions of the leaves asextracted by etherized tenth molar hydrochloric acid showedno relationship with the total iron but a very significant linearrelationship was found between the active iron fraction andthe ratio of total phosphorus to total iron. Recalculation of results presented by other investigators formaize plants grown in soil with various levels of moisture,phosphorus and iron also showed a highly significant linearrelationship between the active iron fraction and the ratioof total phosphorus to total iron. Lycopersicon esculentum L., tomato, ‘active iron’, phosphorus, Zea mays     

贡湖湾退圩还湖区水位高程下植被分布格局与土壤特征

为揭示水陆交错带水位高程下植被分布格局、多样性指数和土壤特征的变化,于2015年10月对贡湖湾湿地北部生态修复区不同水位高程下植物群落组成和土壤特征进行调查,结果表明:整个研究区有165种植物,隶属65科、142属,多为多年生植物且受人为影响严重;随水位高程增加,植物群落R、H、D、J呈现逐渐递增趋势,具体表现为常年水淹区G1季节性水淹区G2水淹区G3;土壤容重及机械组成中粉、黏粒含量随水位高程升高而增加;随土壤营养物渐增其植物群落多样性增加,多样性和优势度指数与土壤全氮(TN和有机质(OM)负相关。OM含量呈"V"型先减后增分布;TN呈逐渐增多的趋势;速效钾(EP)含量无明显波动,约为13.50 mg/kg;有效磷(AP)含量先减少后基本不变;4个多样性指数间正相关;TN与OM显著正相关(R~2=0.533);OM与EP负相关(R~2=-0.144;TN与丰富度、多样性、优势度正相关;AP与4个多样性指数均正相关;pH值与4个多样性指数负相关;回归分析可见,TN和OM是影响植物群落多样性的关键因子。科学的植被管理、全面调控土壤营养盐含量有助于水陆交错带植被恢复。     

Agricultural non-point source pollution in the Yongding River Basin

More and more nitrogen and phosphorus chemical fertilizers are applied in the upstream of the Yongding River Basin. With the aid of convertibility between emergy and value, the calculated ESI (Environmental Sustainability Index) of basin agricultural production is 0.1056, indicating that local agriculture is seriously unsustainable. According to the different combining types of nitrate and ammonium salts with soil particles, soil nitrogen losses under the influence of rainfall-runoff are quantitatively evaluated from the perspective of the nitrogen cycle. By virtue of the content of dissolved and particulate phosphorus in soil, the calculation process for soil phosphorus loss is modeled according to the field runoff volume. The total nitrogen and total phosphorus losses from soil are 96 kg hm⁻² and 9 kg hm⁻², respectively. The calculation result of nitrogen and phosphorus losses in the basin is certainly reasonable. Finally, the research emphasis of calculation method for reducing basin agricultural non-point source pollution is represented from management level.     

The formation,morphology and anatomy of cluster root of Lupinus albus L. as dependent on soil type and phosphorus supply

The effect of phosphorus supply on the formation, morphology and anatomy of cluster roots of Lupinus albus L. cv Ultra grown in a loam and two sandy soils was examined relative to its effect on total root length, shoot weight and the phosphorus concentration of the shoots. The loam soil was most conducive to the formation of cluster roots. Cluster roots growing in the sandy soils developed to a lesser extent on plants of an equivalent phosphorus status, suggesting that some biotic or abiotic factors independent of phosphorus supply were also operating. The presence of mature cluster rootlets on a length of lateral root increased the root surface area by 14–22 times of an equal length of lateral roots not bearing cluster rootlets. The application of phosphorus decreased cluster-root length, whereas total root length showed a steady increase. There was an inverse relationship between cluster-root production and phosphorus concentration in shoots ranging from 2 to 8.5 mg g^–1 with the critical phosphorus level for maximum shoot growth being around 2.5 mg g^–1. Cluster roots formed in solution culture were not well developed in comparison with those grown in the loam soil or nutrient solution with added loam soil. The organisation of the cluster rootlet was similar to that of the lateral roots. Mature rootlets lacked an apical meristem and a vascular cambium with a reduced root cap and cortical tissue.     

川西亚高山三种森林恢复途径对土壤生物有效磷的影响

土壤生物有效磷在提高森林生产力和生物地球化学循环中起着至关重要的作用,研究不同森林恢复途径对土壤生物有效磷的影响对于退化森林的适应性恢复和可持续经营具有重要意义。选取川西亚高山不同恢复途径下形成的3种森林类型,即粗枝云杉人工林（人工种植,PF）、岷江冷杉-红桦天然次生林（自然更新,NF）和粗枝云杉阔叶混交林（人工种植后自然更新,MF）,采用基于生物有效性的土壤磷分级方法测定土壤生物有效磷（CaCl₂-P、Citrate-P、Enzyme-P和HCl-P）,探究不同森林恢复途径对土壤生物有效磷的影响。结果表明：不同森林恢复途径对土壤生物有效磷影响显著（P<0.05）,NF和MF的土壤Citrate-P和Enzyme-P显著高于PF（P<0.05）,而PF的土壤HCl-P显著高于NF（P<0.05）。自然更新是3种森林恢复途径中最能提高土壤生物有效磷的方式。3种森林恢复途径下的土壤生物有效磷组分与速效磷均呈现显著的正相关关系,且NF的土壤速效磷与生物有效磷的相关性更强（CaCl₂-P除外）。显著影响NF土壤生物有效磷的土壤理化性质有全钾、铵态氮含量和pH值,且全钾对NF的土壤生物有效磷变异的解释程度最高（r²=0.63,P=0.001）。土壤pH值、钙和可溶性有机碳含量是显著影响MF土壤生物有效磷的主要土壤理化性质（P<0.05）。对PF的土壤生物有效磷具有显著影响的土壤理化性质是土壤有机碳、铁和可溶性有机碳含量。土壤理化性质对3种恢复途径下森林土壤生物有效磷的解释率均超过了80%,森林恢复途径对土壤生物有效磷的影响与土壤理化性质有关。     

The variability in total and extractable soil phosphorus under a grazed pasture

A comparison of the total soil phosphorus (P) and extractable soil P between 224 samples of topsoil from an area of ~27 m² within a grazed, established grass/clover sward has been made. The values of total soil P displayed an approximately normal distribution around a mean concentration of 1264 mg P kg-1 and were positively correlated to acetic-acid-extractable P which accounted for <2% of the total soil P. The amount of total water-extractable P was much smaller (~0.4% of total soil P) and was not significantly correlated with either the concentration of total soil P or acetic-acid-extractable P. A variable proportion (from less than 5 to 60%) of the total water-extractable P was present in a non-molybdate-reactive form, and there was no apparent relationship between these molybdate-reactive and molybdate-unreactive forms. All variograms showed a positive intercept on the ordinate. For acetic-acid-extractable P, the greatest proportion of variance was attributable to the molybdate-reactive P fraction, while it was equally proportioned between molybdate-reactive and -unreactive P forms in water extracts. The greatest variance usually occurred at the maximum sampling distance (18 m). However, even at the smallest distance (11 cm) the variability in total acetic-extractable P was 2.35 mg P kg-1 and water-extractable P was 0.45 mg P kg-1. Therefore the roots of individual plants within the studied pasture may encounter considerable variability in the concentration of available phosphorus. The potential variability of phosphorus found between rooting zones of different individual plants was greater than that likely to be encountered within the area exploited by any one individual root system.     

定位施肥对紫色菜园土磷素状况的影响

基于紫色菜园土壤莴笋-白菜轮作3a的12季连续定位施肥试验,研究施肥对土壤磷素状况的影响。结果表明,在紫色土上以化肥为基础增施有机肥(泥炭或菜籽粕)既提高土壤磷含量,又增加无机磷组分中有效磷源和缓效磷源的比例,且不会增加磷素淋失的风险,是所有处理中最优者;增磷、增钾处理虽然提高了土壤磷含量,但未能提高速效磷源与缓效磷源的比例;增氮、增硼及常规施肥降低土壤磷含量和提高无效磷源的比例;无肥处理磷含量最低,无效磷源比例最高。紫色菜园土无机磷约为有机磷的4—6倍,无机磷各组分以钙磷为主,占I-P总量的60.89%—67.92%,显示紫色土风化程度较低。各形态磷素呈Ca10-P>Ca8-P>Fe-P≈Al-P≈OC-P>Ca2-P序列变化,其中Ca2-P和Al-P总共仅占无机磷总量的11.47%—19.43%,表明紫色土中对植物最有效的磷源不足;而Ca10-P和OC-P共占无机磷总量的42.48%—59.55%,意味着紫色土无机磷有一半左右是以作物不可利用的形态存在的。紫色土全磷与无机磷、有机磷、Ca2-P、Ca8-P、Al-P、Fe-P、OC-P及Ca10-P呈显著正相关;无机磷与多种形态磷呈显著正相关(除有机磷、Ca2-P、有效磷外);有机磷与全磷、Ca2-P显著正相关;有效磷与全磷、Ca2-P、Al-P、Fe-P显著正相关;无机磷组分间也都存在显著正相关关系(OC-P与Ca10-P间有极显著正相关,但它们与其它无机磷组分无相关性)。表明在土壤磷的整个循环系统中,不同组分无机磷与有机磷之间处于一个动态平衡中,它们之间存在着相互影响和制约。土壤pH与各形态磷关系密切。对土壤有效磷与无机磷组分间的关系进行系统分析,简单相关分析结果土壤有效磷与Ca2-P、Fe-P呈极显著正相关,与Al-P呈显著正相关,与Ca8-P、OC-P、Ca10-P正相关但不显著;通径分析结果对土壤有效磷直接影响较大的无机磷组分是Al-P、Ca8-P与Ca2-P,其中Ca8-P的直接影响为负效应;逐步回归分析结果与通径分析一致。综合分析得出,Ca2-P、Al-P是最有效的磷源,Fe-P、Ca8-P次之,Ca10-P与OC-P是非有效磷源。莴笋和白菜产量与紫色土壤Ca2-P、Ca8-P、Al-P、Fe-P呈显著正相关,与OC-P、Ca10-P无相关性。紫色土各形态无机磷与两种蔬菜产量的相关系数r大小依次为Ca2-P>Fe-P>AL-P>Ca8-P>Ca10-P>OC-P,这与各形态无机磷与有效磷简单相关分析的结果一致。     

甘肃中东部地区9种薹草属植物分布区群落特征和土壤养分状况

为探究薹草属(Carex L.)植物在不同植被类型中的分布状况,该研究对甘肃中东部地区9种薹草属(Carex L.)植物分布区的群落特征进行调查,并对土壤养分状况进行比较分析,以揭示野生薹草群落物种多样性和分布特征与土壤环境因子间的关系。结果表明：(1) 9种薹草群落物种多样性差异性较大,Shannon-Wiener多样性指数(H)、Simpson优势度指数(D_si)均以青绿薹草群落最高,亚柄薹草最低;Patrick丰富度指数(R)以异穗薹草群落最高,细叶薹草群落最低;Pielou均匀度指数(J_sw)以凹脉薹草群落最高,亚柄薹草最低。(2) 9种野生薹草属植物适宜生长的土壤pH呈中性或弱碱性,且有机质、氮素、钾素含量较丰富,磷含量偏低;土壤有机质、pH、全氮、全磷、全钾、碱解氮、速效磷、速效钾含量的平均值分别为41.07 g·kg^-1、8.35、1.16 g·kg^-1、0.65 g·kg^-1、5.60 g·kg^-1、47.94 mg·kg^-1、5.82 mg·kg^-1和100.60 mg·kg^-1。(3) 9种薹草属植物群落物种多样性与全氮、全磷、全钾、碱解氮、有机质、降雨量和海拔呈正相关关系,而与土壤pH、速效磷、速效钾呈负相关关系,且降雨量、土壤pH、速效磷和有机质对9种野生薹草属植物群落物种多样性影响较大。     

赤红壤植蔗坡地坡面径流及溶解态氮磷流失特征

为探究南方高强度、高频次降雨下赤红壤区坡耕地土壤侵蚀及氮磷养分流失的特征,基于野外径流小区原位观测试验,通过测定自然降雨下赤红壤植蔗坡地坡面径流和溶解态氮磷流失量,探讨自然降雨下甘蔗种植对赤红壤坡面径流及溶解态氮磷流失的影响。结果表明：(1)2019年和2020年,径流量分别为1111.3 m~3/hm~2和3269.4 m~3/hm~2,硝态氮(NO~-₃-N)流失量分别为1.39 kg/hm~2和15.60 kg/hm~2,铵态氮(NH~+₄-N)流失量分别为0.37 kg/hm~2和1.02 kg/hm~2,可溶性磷流失量分别为0.20 kg/hm~2和0.27 kg/hm~2。2019年和2020年植蔗坡地径流及溶解态氮磷流失量均集中在6月份,占流失总量的45%以上,硝态氮(NO~-₃-N)是径流氮素流失的主要形式,占79%以上。此外,2019年和2020年5月至8月,侵蚀性降雨场次分别为18次和23次,侵蚀性降雨量分别为407.8 mm和668.0 mm。(2)不同侵蚀性降雨条件下,植蔗坡地溶解态氮磷流失量及其...     

土壤磷含量与有效性对N2O排放量的影响元分析

土壤氧化亚氮(N₂O)主要产生于土壤微生物参与的氮循环过程,其排放量受磷含量及有效性影响。添加磷肥有助于缓解陆地生态系统磷限制,提升土壤有效磷含量,进一步影响土壤微生物对氮的利用,同时控制N₂O排放。然而不同独立实验中N₂O对外源磷添加的响应差异较大。研究从发表的中、英文文献中收集了54份关于施用磷肥与N₂O排放量的观测结果,采用元分析方法确定添加外源磷后N₂O排放量的响应差异及潜在影响因素。结果表明：(1)外源磷添加对土壤N₂O排放量影响不显著;但在磷肥施用量> 50 kg P/hm²的室外实验中土壤N₂O排放量显著降低了32.5%;施用NaH₂PO₄的室内实验中N₂O排放量显著降低了18.4%。(2)土壤N₂O对外源磷添加响应的高变异性是磷肥施用量和土壤含水量、土壤pH、土地利用类型、磷肥种类、纬度和实验时间多种影响...