Complete stabilization of severely As-contaminated soil by a simple H2O2 pre-oxidation method combined with non-toxic TMT-15 and FeCl3·6H2O

The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15(Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6 H2O stabilization method. The results showed that the combination of the two stabilizers(i.e., TMT-15 and FeCl3·6 H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6 H2O stabilization approach not only converted the As(Ⅲ) to As(Ⅴ) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6 H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6 H2O could render the severely As-contaminated soil safe for disposal in a landfill.

Effects of recovery time after fire and fire severity on stand structure and soil of larch forest in the Kanas National Nature Reserve, Northwest China

Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.

Short-term effects of different fire severities on soil properties and Pinus halepensis regeneration

Considering that diverse fire severities can affect soil properties differently,the aim of this study was to examine to what extent changes in soil properties caused by fire could condition seedling establishment.This new approach is for identifying a new fire cause-effect chain to qualify the impacts of fire on soils with the purpose of using fire as a tool in forest management to favour Pinus halepensis Mill.regeneration.The study area was a reforested P.halepensis area which had been crossed by fire for78.8 ha,causing various degrees of damage.The forest was subdivided into three large areas according to the gravity of crown scorch,[low(LS),medium(MS)and high(HS)severity],on the basis of needle yellowing which usually occurs after exposure to direct flames.Results showed significant differences in soil properties with respect to fire severity.In the HS area,total nitrogen and carbon were considerably reduced while ash and phosphorus contents significantly increased.The changes in soil properties,in particular to nutrient levels,affected P.halepensis regeneration,mainly the first year after the fire.Greater regeneration occurred in areas affected by moderate fire severity in which the temperatures reached increased the mineralization of soil organic matter with the consequent release of nutrients available for seedling growth.Additionally,moderate fire severity suppressed the regeneration of grasses,reducing the interspecific competition.Heights of seedlings were inversely proportional to the density of grasses.Where the number was abundant(LS),the height was modest;conversely,where the number was low(HS),the greater hypsometric differentiation of pine seedlings was observed.These results suggest that moderate fire severity represents an environmental stress(hormesis)altering microscale conditions to increase pine germination and establishment.The exposure of P.halpensis to a moderate environmental factor that is damaging at higher intensities,induces an adaptive beneficial effect on seedling regeneration.This data can re-evaluate the assertion that coniferous burned areas,if left unmanaged,would remain unproductive for an indefinite period.

Effect of fire severity on physical and biochemical soil properties in Zagros oak(Quercus brantii Lindl.)forests in Iran

Fire affects the physical and chemical properties and soil biological activity of natural ecosystems. This study was conducted in the Miyan Tang region, Ilam Province in western Iran. The study site was 110 hectares,where we sampled soils in areas that were classified by fire severity: low(LS), high(HS) and medium severity(MS),and unburned(UB), which served as the control. In each severity class, 25 transect points were randomly selected for measurement. Around each transect plot center, 3 soil samples were selected randomly and soils collected from the 0 to 20 cm depth were combined into a composite sample that was used in laboratory analysis to represent conditions at that point. Plots in the UB and LS fire classes had similar soil conditions and had higher values of factors such as saturated moisture, organic carbon, carbon dioxide,and silt and clay content. In contrast, plots in the HS and MS fire severity classes were clustered in the positive direction along the first axis that represented gradients in soil acidity, electrical conductivity, cation exchangecapacity, accessible phosphorus, accessible potassium,bulk density, and sand. Soil attributes were similar in areas of HS and MS fire severity classes, whereas soil conditions in the LS class and UB controls were most similar. Fire in the LS areas either did not significantly alter the physical–chemical soil properties and microbial basal respiration, or soils were able to recover quickly after being burned.

Impact of a Low Severity Fire on Soil Organic Carbon and Nitrogen Characteristics in Japanese Cedar Soil, Yamagata Prefecture, Japan

Slash and burn practices are widely used around the globe with different degrees of success which are mostly related to the impact of fire on soil properties. In Japan slash and burn practises, known as Yakihata, have a long history and are still used in Yamagata Prefecture today. The purpose of this study was to determine the impact of a low severity controlled fire underneath Japanese cedar (Cryptomeria japonica) on brown forest soil (Cambisol). Japanese Cedar is the dominant species among plantations in Japan. We measured organic carbon and nitrogen content as well as changes in carbon (δ13C) and nitrogen (δ15N) stable isotope composition in a steep west facing slope under heavy precipitation (~2600 mm/a) and heavy snowfall (~3 to 4 m/a). The accumulation of Ctotal and Ntotal at the bottom of the slopes was remarkably higher at the slash and burned site than in the control forest site. After slash and burn δ15N isotopes in the slope in general became significantly lighter than in the control forest while the δ13C did not show any significant difference between the two sites except at the bottom of the slopes where δ13C was heavier in the forest. The results show that Ctotal and Ntotal values as well as the isotopes ratios of C and N change with decreasing elevation in the forest as well as in the burned site being consistent with leaching and erosion. The changes in soil nitrogen and carbon isotopes at the bottom of the slope appear to be related to the transport of material with different isotopic composition from the upper slope. The effect of the low severity fire (as part of the slash and burn practice) on soil organic carbon and nitrogen movement was enhanced by the steepness of the slopes and the high precipitation of Shonai region.

中南半岛野火变化特征及其与土壤水分的相互作用

[目的]分析野火变化特征并探讨火点数与不同深度土壤水分的关联性,为评价生态文明建设和人类生产生活提供科学依据。[方法]基于SNPP/ⅦRS卫星火点监测、火烧迹地和SMAP土壤水分等数据,使用统计方法多角度对2016—2021年中南半岛野火变化特征进行分析,探讨不同干湿条件下火点数与0—5cm和0—100cm2个不同深度土壤水分的相互作用。[结果]①中南半岛火点数和火烧迹地年内主要出现在2—4月,二者在时空分布上具有较高的一致性,多集中在缅甸西部与印度接壤区域、缅甸中部以东和老挝北部。②2—4月火点主要出现在林地、灌木地和耕地,而易发生在归一化植被指数(NDVI)为如下3个等级的区域:0.2<NDVI≤0.4,0.4<NDVI≤0.6,0.6<NDVI≤0.8,但其所占比例随地表覆盖类型和月份的不同存在一定差异。③特旱和重旱条件下火点区明显较无火点区广,火点数集中程度更高;土壤水分随火点数的增加整体呈减少趋势,但极端干湿条件下,土壤水分随火点数变化存在由减转增的“拐点”,且“拐点”值随时间延后而减小。④滞后1~2个月的火点数与土壤水分相关程度最高;日时间尺度上土壤水分对火点数变化同期响应快,且土壤水分和NDVI高的区域关联性更强。[结论]土壤水分亏缺是中南半岛火点高发的重要驱动力。火点数与土壤水分之间相互作用,二者之间存在显著负向关联性。

土体工程地质层划分及其在城市地下空间开发中的应用

城市地下空间包括岩土体本身的密实部分以及天然或人工形成的无岩土体的空间部分,既是重要的自然资源,又是其它地下自然资源的载体。随着城市的不断发展,地下空间构建立体城市已成为必然选择。城市地下空间开发多在土体中进行,地下工程建设的成本、难度与土体质量息息相关。针对常州市土体工程地质层划分标准不统一的现状,基于城市地质调查项目获取的海量地质钻孔和土体物理力学指标测试结果,综合考虑沉积时代、物质成分、工程特性指标等因素,采用剖面绘制法对常州市100m以浅土体工程地质层进行划分,建立基本地层结构和层序编码,通过工程地质层物理力学参数离散性和三维模型平滑度验证划分结果合理可行。将土体工程地质层划分结果应用到桩基持力层选择、地下空间竖向分层规划、地下空间开发适宜性评价、多种地下资源协同利用等方面,可为城市地下空间规划、建设、管理提供基础数据和相关借鉴。

Spatial Estimation of Soil Erosion Risk Using RUSLE Approach, RS, and GIS Techniques: A Case Study of Kufranja Watershed, Northern Jordan

Wadi Kufranja catchment (126.3 km2), northern Jordan, was selected to estimate annual soil loss using the Revised Universal Soil Loss Equation (RUSLE), remote sensing (RS), and geographic information system (GIS). RUSLE factors (R, K, LS, C and P) were computed and presented by raster layers in a GIS environment, then multiplied together to predict soil erosion rates, and to generate soil erosion risk categories and soil erosion severity maps. The estimated potential average annual soil loss is 10 ton·ha-1·year-1 for the catchment, and the potential erosion rates from recognized erosion classes ranged from 0.0 to 1850 ton·ha-1·year-1. About 42.1% (5317.23 ha) of the catchment area was predicted to have moderate risk of erosion, with soil loss between 5 - 25 ton·ha-1·year-1. Risk of erosion is severe to extreme over 31.2% (3940.56 ha) of the catchment, where calculated soil loss is 25 - 50 and >50 ton·ha-1·year-1. Apart from the gentle slopes of the alluvial fan (Krayma town and surroundings), the lower and the middle reaches of the watershed suffer from severe to extreme erosion risk. High terrain, slope steepness, removal of vegetation, and poor conservation practices are the most prominent causes of soil erosion.

春小麦对骤旱的响应特征及其阈值分析

与缓慢发展的干旱过程不同,骤旱具有发生速度快,短期内可致害的特点。目前,关于作物骤旱致害的临界阈值及其调控机制尚不清楚。以春小麦为供试作物,通过桶栽试验,模拟研究骤旱过程中小麦受旱致害的过程特征及其控制因素。结果发现,发生骤旱时土壤含水量下降呈先快后慢的变化趋势,叶片水分和叶水势则呈先慢后快的指数变化趋势。叶片光合生理指标对土壤水分的下降存在明显的阈值响应,且不同生理指标的阈值并不完全相同,其中净光合速率与表征叶片光合能力的指标(最大羧化速率)对土壤有效含水量的响应阈值为0.4,气孔导度和蒸腾速率对土壤有效含水量的响应阈值分别为0.5和0.4。而小麦光合生理指标对叶片水分和叶水势的阈值响应并不明显。同时依据各生理指标相关和通径分析结果得出,骤旱发生时引起小麦叶片净光合速率快速降低的主导因子为非气孔因素,而并不是以往作物受旱研究中的气孔因素。本研究结果有望丰富干旱影响认知,并可为科学应对干旱提供依据。

兴安落叶松林火烧迹地土壤理化性质驱动因子

探索火烧迹地土壤理化性质的驱动因子是解释生态系统响应火干扰机制的重要组成部分。旨在分析兴安落叶松林火烧迹地土壤理化性质的决定因子,深入认识火干扰在北方森林生态系统所扮演的角色,为北方森林火烧迹地火后恢复、林业可持续发展提供科学支持和理论依据。以过火后1 a的兴安落叶松林火烧迹地为研究对象,设置了不同火烈度和立地条件的火烧迹地及对照研究样地共计35块。在每个研究样地记录了树种、胸径、存活状态等乔木数据,测量了坡向、坡位、坡度、海拔等地形数据,利用植被变化情况量化了火烈度。分别采集了0—5 cm和5—10 cm的土壤样品并测定其9种理化指标,对比了过火与未过火样地这些土壤理化指标的差异。然后,分析了各土壤理化指标与火烈度量化结果的关联趋势,比较了火烈度、地形和乔木因子对火烧迹地土壤理化性质的影响程度。与对照样地相比,火干扰提升了土壤理化指标观测值的离散程度,显著提高了0—5 cm土壤含水率(MC)(P<0.05)和5—10 cm土壤MC、总氮(TN)、总有机碳(TOC)含量(P<0.05)。土壤理化性质与火烈度有明显关联趋势的并不多,观察到0—5 cm土壤MC随火烈度指数的增加而减少,0—5 cm土壤无机氮与5—10 cm土层土壤pH、速效钾(AK)、铵态氮(NH_(4)^(+)-N)随火烈度指数的增大而增大。相关分析表明,地形因子与火烧迹地土壤理化性质关联程度较高,坡位、坡度、坡向与土壤吸湿含水率(HMC)、MC、硝态氮(NO_(3)^(-)-N)和5—10 cm土壤总氮(TN)、总有机碳(TOC)均呈显著负相关(P<0.05),而与土壤AK、pH、NH_(4)^(+)-N和有效磷(AP)则以正相关为主,其中坡度与0—5 cm土壤AK、pH、NH_(4)^(+)-N和AP均呈极显著的正相关(P<0.01)。方差分解分析结果表明,对照样地土壤理化指标的变异主要由乔木因子和地形因子共同解释,但在火烧迹地,乔木因子总解释比例降低了,而地形因子单独解释的比例增加了,两者对于土壤理化指标变异的共同解释比例大幅降低了。火干扰能够提升地形对土壤理化性质的影响程度。地形是火烧迹地土壤理化性质差异的主导因子,其影响较火烈度更为深刻,因此,当火烈度相同但地形不同时,火干扰引发的生态系统响应可能不同。所以,地形的主导作用可能是导致在不同区域研究火烈度与土壤理化性质的关系得出不同结果与结论的重要原因之一。

不同火烈度对四川泸山林场云南松林土壤有机碳组分的影响

林火通过改变土壤理化性质显著影响土壤固碳能力及土壤有机碳各组分含量。阐明不同火烈度对云南松林土壤有机碳的影响,对于云南松林火后生态系统恢复及土壤碳库管理具有重要意义。以火烧2年后四川泸山林场云南松林0—5、5—10、10—15、15—20cm层土壤为研究对象,根据不同火烈度(未过火、低烈度、中烈度、高烈度)设置3块20m×30m样地,共12块样地,野外采集土壤样品,室内测定土壤全氮、容重等理化性质和土壤有机碳(Soil organic carbon,SOC)、土壤活性有机碳(易氧化有机碳,Readily oxidizable carbon,ROC;颗粒有机碳,Particulate organic carbon,POC;微生物生物量碳,Microbial biomass carbon,MBC;水溶性有机碳,Water-soluble organic carbon,WSOC),采用方差分析研究不同火烈度下土壤有机碳各组分含量的差异性和变化趋势,并采用相关性分析和冗余分析从土壤理化性质角度探究林火对土壤有机碳的影响机制。研究结果表明:(1)不同火烈度显著影响土壤理化性质,其中土壤全氮、有效磷、阳离子交换量、毛管孔隙度、总孔隙度随火烈度增大而增加,而土壤pH、速效钾、碱解氮、容重随火烈度增大而减少。(2)SOC随火烈度增大而减少,其中5—10cm土层降幅最大为44.79%;4种土壤活性有机碳随火烈度增大而减小,其中0—5cm土层下降幅度最明显,各组分降幅大小依次为ROC(36.31%—61.31%)>POC(30.05%—53.61%)>MBC(20.60%—48.19%)>WSOC(13.47%—29.29%),不同组分对林火的不同响应显著影响了土壤ROC、POC、WSOC的占比。(3)土壤有机碳及其活性组分与阳离子交换量、毛管孔隙度、总孔隙度、有效磷、碱解氮呈显著正相关(P<0.05),与容重呈极显著负相关(P<0.01)。火烧后土壤有机碳的变化主要与阳离子交换量、容重、全氮、含水率有关,且阳离子交换量影响最大(解释率为61.7%)。

泡沫轻质土渗透及吸失水性能试验研究

通过对湿重度分别为5.5 k N/m^(3)、6 k N/m^(3)的泡沫轻质土进行渗透及吸失水试验,研究了泡沫轻质土的孔隙状态、渗透系数及吸失水性能。试验结果表明:气泡混合轻质土是一种高孔隙率材料,其孔隙占比在75%以上,渗透系数约为10^(-5)~10^(-6)数量级,介于粉质粘土与粘土的渗透系数之间;受水浸泡后,泡沫轻质土容重最大增加约25%,失水后容重仍然有约9.5%增加量,在工程设计中应根据不同置换路基施工环境对设计容重按照1.0~1.25之间进行修正。

退化红壤不同治理模式对土壤肥力的影响

采取4种不同治理模式对福建省长汀县花岗岩区红壤严重侵蚀地进行治理，1992年对各治理模式及相应对照的土壤化学性质、土壤微生物、土壤酶活性、土壤呼吸作用进行研究，结果表明，治理后土壤细菌、真菌、放线菌数量及微生物总数明显增加，土壤水解性酶和氧化还原酶活性及土壤呼吸作用强度得到显著的加强，土壤养分贮量和速效养分供应强度得到明显改善，土壤肥力得到不同程度的恢复。表明采用合适的生物措施，辅以必要的工程措施，是改善严重退化红壤肥力有效途径之一。

火烧对胡桃楸人工林土壤化学性质的影响

对胡桃楸人工林进行控制火烧,利用摄像机记录火烧情况,对火烧前后土壤pH值、全氮、速效氮、速效磷、钾、钙、镁等化学性质的变化及其与林火能量释放指标的相关性进行了分析。结果表明,火烧使胡桃楸人工林土壤肥力总体增加。火烧后土壤pH值、速效磷、钾、钙、全氮、速效氮增加,镁变化不显著。火烧对土壤各主要化学性质影响的程度与点烧时的能量释放有关,其中全氮、速效氮、速效磷的绝对变化值与样地总能量释放呈负相关,镁的绝对变化值和钙的相对变化值与单位面积能量释放呈正相关,而pH值和钾与这两个能量释放指标都不相关。上述所有化学性质的变化与林火强度都不存在线性相关关系,以林火强度为依据划分的轻度地表火和低度地表火对土壤各化学性质变化程度没有影响。同时对林火烈度与林火能量释放诸指标的关系进行了讨论。

有机酸对污染土壤重金属的淋洗效果研究

以湖南水口山某铅锌选矿厂附近受Zn、Pb、Cu、Cd严重污染土壤为对象,采用振荡淋洗技术,研究了有机酸在不同浓度、时间和液固比条件下对重金属的去除效果。实验结果表明,柠檬酸和酒石酸对重金属具有很好的去除效果,而草酸的去除能力很低;柠檬酸和酒石酸对Cd的去除效果最好,分别为61.5%和55.25%。随着时间的增加,有机酸对重金属的去除效率逐步提高,8h效果最好。柠檬酸和酒石酸对重金属的去除能力均依次为Cd>Zn>Pb>Cu,柠檬酸对重金属的去除率分别为59.5%、49.33%、43.48%、26.25%,酒石酸对重金属去除率分别为58.75%、46.4%、35.86%、34.4%。实验还发现固液比对重金属的淋洗效果影响很小。

县域土壤侵蚀严重性评价方法初探——土壤侵蚀严重指数的定义与应用

为评价县级行政单位土壤侵蚀的严重性,提出了“土壤侵蚀严重性指数”及计算方法,并在计算我国各县级行政单位土壤严重指数数值的基础上,讨论了土壤侵蚀严重指数的分级。土壤侵蚀严重指数不仅全面反映了县域的土壤侵蚀面积,而且区别反映了各级土壤侵蚀强度。土壤侵蚀严重县的分布及其侵蚀面积占全国土壤侵蚀总面积的比重,表明了土壤侵蚀严重指数不仅可以用来比较县与县之间土壤侵蚀严重程度的差异,而且可以评价土壤侵蚀在分布上的集中性。

帕默尔旱度模式的进一步修正

为了正确评估干旱 ,根据帕默尔旱度模式的思路和 1 986年安顺清等人修正的帕默尔旱度模式 ,我们以济南、郑州和太原 3站逐年逐月气温和降水等作为基本资料 ( 1 961～ 2 0 0 0年 ) ,以哈尔滨、佳木斯、呼和浩特、沈阳、北京、固原、西安、汉中、青岛、德州、运城、长沙、武汉、南昌、杭州、福州、广州、昆明、南宁、成都和贵阳 2 1个站的有关资料 ( 1 961～ 2 0 0 0年 )为权重因子修正资料 ,并且在计算可能蒸散时选用了FAO推荐的彭曼 蒙蒂斯公式。另外 0～2 0cm和 2 0～ 1 0 0cm土层的土壤田间有效持水量根据我国测定的资料和土壤特性确定 ,对帕默尔旱度模式进行了进一步修正。利用此模式计算了我国北方地区 1 39个站点 ( 1 961年1月～ 2 0 0 0年 1 2月 )的帕默尔指数值。将计算的帕默尔指数值与一些文献记载的实际旱涝灾情相对照进行验证 ,表明进一步修正的帕默尔旱度模式能较为准确地评估旱涝情况 。

哀牢山常绿阔叶林水源涵养功能及其在应对西南干旱中的作用

为了解云南哀牢山中山湿性常绿阔叶林在2010年初西南地区特大干旱中是否遭遇水分胁迫,及其水源涵养功能在应对干旱中的作用,测定了该森林土壤和主要树种在2010年旱季的水分状况,并对比研究了原生林和森林经砍伐烧垦后形成的毛蕨菜-玉山竹群丛的土壤持水、凋落物持水、水面蒸发和土壤水分季节动态。结果表明:常绿阔叶林主要树种在2010年初西南特大干旱中并未遭受水分胁迫(最旱月叶片凌晨水势高于-0.4 MPa)。虽然常绿阔叶林土壤含水量和地下水位在最旱月都达到了有观测以来的最低点,但主要根系分布区的土壤水势仍不低于-0.5 MPa,并高于毛蕨菜-玉山竹群丛。森林较好的水分状况和原生常绿阔叶林较好的水源涵养功能有关。常绿阔叶林的土壤总持水量尤其是非毛管持水量要显著大于毛蕨菜-玉山竹群丛,同时也大于云南地区的一些次生林和人工林。常绿阔叶林地表丰富的凋落物通过持水和抑制土壤蒸发也对水源涵养有一定作用。哀牢山常绿阔叶林良好的水源涵养功能,充足的土壤地下水储存弥补了旱季和特大干旱中降水的不足。结果指示原生林在水源涵养中不可替代的作用,以及加强原生林保护在提高区域抗干旱能力中的重要意义。

增施磷肥对重度盐碱地食葵生长及土壤微生物区系的影响

采用大田筒栽试验,设置4个施磷(P2O5)水平:CK(不施磷)、P4(60 kg·hm^(-2))、P8(120 kg·hm^(-2))、P12(180 kg·hm^(-2)),研究了重度盐碱地施磷对食葵叶片保护酶活性、植株干物质积累、磷吸收以及施磷后土壤微生物区系变化特征的影响。结果表明:增施磷显著提高了食葵叶片保护酶活性,食葵叶片超氧化物歧化酶(SOD)与过氧化氢酶(CAT)活性在施磷达到P4水平即显著提高,且达到P12水平又出现显著增加;而过氧化物酶(POD)活性在施磷量达到P12水平才显著增加。叶片丙二醛(MDA)含量与SOD活性保持相对同步,在施磷量P4、P8水平并没有显著降低,直至达P12水平才显著下降,比CK降低31.40%。食葵叶片、籽粒、根干重及根冠比在施磷量达到P12水平时也显著高于其他处理。食葵籽粒、根系磷积累量均随着施磷量增加显著提高,且各施磷处理食葵地上部、根系含磷量也均显著高于CK,但P12与P8处理差异不显著,另外施磷有利于食葵吸收的磷素由根系向地上部转移运输。增施磷通过调控根系生长以及改善微环境显著增加了土壤细菌、放线菌、真菌等可培养微生物数量,且以P12处理增加最多。食葵盛花期和成熟期也均以P12处理优势菌群种类最丰富,其中盛花期P12处理有数量较多的节杆菌属(Arthrobacter),在食葵收获后则含有考克氏菌属(Kocuria)、葡萄球菌属(Staphylococcus)和噬几丁质菌属(Chitinophaga)。综合比较来看,河套灌区重度盐碱地施磷180 kg·hm^(-2)可以显著增加食葵叶片保护酶活性,促进食葵生长及磷吸收积累,提高食葵抗性,同时有利于土壤微生物多样性增加。

重度盐碱地营造杨树人工林土壤改良效果

为探讨重度盐碱地营造杨树人工林对土壤的改良效果,本实验以黑龙江省肇东市重度盐碱地作为研究对象,采用小穴改良"一字沟"觅食丘式原位修复、小穴改良"十字沟"觅食台式原位修复和小穴改良"井字沟"觅食坛式原位修复的方法对重度盐碱地进行改良。研究结果表明:实施不同改良措施后土壤特性发生了显著变化,土壤pH值、电导率含量显著下降;土壤碳酸根含量显著下降,交换性钙、镁含量显著提高;土壤胡敏酸和壳聚糖含量明显提高,土壤肥力增加。因此,本研究所采用的三种不同的改良措施具有良好的改良效果。