煤矸石组分与表土质地对充填重构土壤导气率的影响

研究煤矸石组分及表土质地对煤矸石重构土壤导气率的影响,探讨重构土壤这种差异显著的非均质土壤导气内在机理,为进一步研究复杂的非均质土壤导气特性提供理论基础。通过在煤矸石中掺杂不同粒径碎石来改变其组分,并利用3种不同质地的土壤在土柱内进行土壤剖面重构,采用一维瞬态法测量其导气率。结果表明:(1)不同碎石粒径和质量分数对混合基质饱和含水量影响不同,掺杂2~5mm粒径碎石,随着质量分数的增加,饱和含水量逐渐增加,从7.29%增加到12.9%;掺杂5~10mm粒径碎石,饱和含水量随着质量分数的增加先增加后减少,分别为7.28%,8.5%,6.9%。(2)煤矸石的导气率远大于土壤,并且煤矸石的导气率对水分的敏感度随质量含水量的增加而增加,而土壤的导气率对水分变化的敏感度均随质量含水量的增加而降低。(3)碎石的存在为大孔隙的产生创造条件的同时也会减少了土壤通气断面,阻隔空气传输的通道。(4)重构土壤导气率受表土质地和底部填充介质的共同影响,覆土土壤导气率决定了重构土壤的导气率大小,而充填基质导气率决定了充填介质对重构土壤导气率影响的系数(Ska)。Ska与充填介质导气率呈显著相关,可以通过指数函数进行拟合(R2=0.93)。通过充填介质及覆土土壤的导气率可以对重构土壤导气率进行估算,简化了重构土壤导气率的测定过程。     

小碎石与细土混合介质的导水特性

含碎石土壤的导水性质研究有利于这种多孔介质水分运动的模拟。本文采用室内定水头法和离心机法分别测定两种质地土壤(壤土、黏壤土)和三种岩性小粒径(2~10 mm)碎石构成的土石混合介质的饱和导水率和水分特征曲线,采用van Genuchten-Mualem模型计算各土石介质的非饱和导水率,分析碎石对土壤导水能力的影响。试验结果显示,风化程度低的碎石对黏壤土具有明显的增大饱和导水率的作用,且碎石含量愈高,增加的效果愈明显;而风化程度高的碎石对土壤结构无明显的改善作用,且对黏壤土具有减小饱和导水率的作用。风化程度低碎石介质的非饱和导水率随土壤水吸力的增加呈现了先大于土壤和土石介质的后迅速减小到低于土壤和土石介质的变化过程。风化程度低的河卵石和风化程度高的粉泥页岩碎屑分别构成的土石介质的非饱和导水率较土壤的低,而风化程度中等的片麻状花岗岩碎块构成的土石介质的非饱和导水率较土壤的高。近饱和状态下,碎石含量高的土石介质的非饱和导水率也相应的高,而较大的土壤水吸力下,土石介质的非饱和导水率呈现随碎石含量的增大而减小变化趋势。试验结论可为含碎石土壤水分平衡研究提供参考。     

保水剂粒径与不同质地土壤吸、失水特性的相关关系

通过室内模拟试验,对2种保水剂4个粒径(0.25~0.5mm,0.5~1mm,1~2mm,2~3mm)的吸、失水特性进行测定分析,同时研究2种保水剂4个粒径分别与砂壤土、壤砂土、砂粘壤土混合后吸、失水的变化特性。结果表明:①2种保水剂的4个粒径段中1~2mm粒径的保水剂吸水量和累积蒸发量最大,不同粒径保水剂随着吸水次数的增多吸水量逐渐降低,且粒径越小下降幅度越大;②保水剂与土壤混合后吸水量减小,初次吸水时土壤含水量与保水剂粒径成反比,随着吸水次数的增多3种质地土壤在保水剂作用下土壤含水量大小顺序分别为壤砂土-砂粘壤土-砂壤土(1~2次)、砂粘壤土-壤砂土-砂壤土(3~5次)、砂粘壤土-砂壤土-壤砂土(6~8次);③2种不同粒径保水剂的施用增加了3种质地土壤的累积蒸发量,壤砂土、砂壤土中0.5~1mm粒径的保水剂累积蒸发量最大,砂粘壤土中1~2mm粒径的保水剂累积蒸发量最大,0.25~0.5mm粒径保水剂在3种土壤中累积蒸发量最小。     

喀斯特地区不同层次土石混合介质对土壤水分入渗过程的影响

桂西北喀斯特地区土壤中常常含有土石隔层,分析其对土壤水分入渗过程的影响有助于深入研究该区水循环机理和促进植被恢复重建进程。通过室内模拟土柱试验,研究了不同土石隔层碎石粒径(5～20,20～40 mm)及土石隔层(土石质量比为1:1)位置(上层(0～20 cm),中层(10～30 cm),下层(20～40 cm))对土壤水分入渗过程的影响。结果表明,碎石粒径为5～20 mm时,土石隔层位于中层时土壤累积入渗量最大。碎石粒径为20～40 mm时,土石隔层位于下层时土壤累积入渗量最大。当土石隔层位置一定时,碎石粒径较小有利于土壤水分入渗;粒径为5～20 mm的土石隔层土壤稳定入渗速率最大,且达到稳定入渗的时间最短,但土层隔层位于下层时均质土壤及不同粒径土壤的稳定入渗速率无显著差异。土石隔层位置和隔层碎石粒径对初始入渗速率没有显著影响;土石隔层位于上层时,土石隔层的存在缩短了水分入渗运移过隔层的时间。土石隔层位于中层时,隔层碎石粒径为20～40 mm时水分入渗到达隔层及运移过隔层的时间最长。土石隔层位于下层时,隔层碎石的存在缩短了水分入渗到达隔层及运移过隔层的时间。Kostiakov入渗模型与Philip方程都可以较好地描述含土石隔层土壤的入渗过程,但Kostiakov入渗模型模拟效果更好。     

土石混合介质水分入渗特性试验研究

土壤中碎石的存在改变了土壤结构和土壤水分运动规律.为研究碎石含量和碎石粒径对土石混合介质水分入渗特性的影响.利用垂直一维积水入渗试验资料对其进行分析.结果表明:土石混合介质的累积入渗量和湿润锋推进速度均小于细土,碎石含量对累积入渗量和湿润锋的影响存在一个转折点.该转折点因粒级不同而不同;碎石含量对含水量剖面的影响表现为含水量随含石量增加而下降;碎石粒径只对混合介质本身的物理特性有影响,对水分入渗无明显影响.     

土壤特性对保水剂持水性能的影响

为研究土壤特性对保水剂持水性能的影响,测试了4种保水剂分别与砂壤土、壤砂土、砂粘壤土1和砂粘壤土2共4种土壤混合后的保水率,混合时土壤为风干土,保水剂与土壤混合的质量百分比为0.5%。结果表明:与单纯保水剂或者保水剂与砂子混合相比,保水剂与土壤混合后可明显降低保水剂的释水速度,提高保水剂的持水能力。土壤特性对保水剂释水速度有明显影响,土壤粘粒含量高,保水剂的释水速度慢,反之,则快。土壤粘粒含量高,土壤含水量高,保水剂表面水势梯度变低,使释水速度变慢;粘粒含量低,水势梯度变大,保水剂释水速率加快。经过7 h的恒温蒸发后,4种保水剂在粘粒含量较高的砂粘壤土(粘粒含量25%)中的保水率比在粘粒含量低的壤砂土(12.5%)中的保水率高43.7%~71.3%,且具有明显的差异。     

土壤特性对保水剂吸水性能的影响

该文测试了保水剂与砂壤土、壤砂土、砂黏壤土1和砂黏壤土2四种土壤混合后的吸水倍率，研究了土壤特性对保水剂吸水性能的影响，混合时土壤为风干土，保水剂与土壤的混合比例为0.5%。结果表明：与对照相比，保水剂与土壤混合后明显降低了吸水倍率，且随着吸水时间加长，降低幅度增大。吸水10 min后，吸水倍率下降14.4%～58.0%，70 min后，下降41.8%～90.2%。研究认为：吸水初期，吸水倍率主要受土壤孔隙特性的影响，随着吸水时间的加长，土壤溶液中离子增多，对保水剂吸水倍率产生了影响。土壤溶液中离子量与黏粒含量有关，黏粒含量高，土壤溶液中离子量大，反之则小，保水剂在黏粒含量高的土壤中的吸水倍率较在黏粒含量低的土壤中低。与土壤混合还改变了保水剂的吸水规律，对照中，吸水倍率随着吸水时间加长而加大，达到最大后趋于稳定；而在土壤中，短时间内吸水倍率达到最大，随着吸水时间加长，吸水倍率逐渐下降。     

生物炭对粉黏壤土水力参数及胀缩性的影响

该文选取2种粒径（细炭0.013～0.048 mm、粗炭0.3～0.7 mm）的生物炭,以2种质量百分比（3%、6%）施入一种粉黏壤土,通过测定不同粒径生物炭及施加比例下土壤的水分特征曲线、饱和水力传导度、收缩性及饱和膨胀率,研究生物炭对粉黏壤土水力参数及胀缩性的影响。结果表明,2种粒径及添加比例的生物炭均降低了粉黏壤土的持水能力。但4种添加生物炭处理相互之间持水能力差异不显著。生物炭可降低粉黏壤土中极微孔隙和中大孔隙的比例,提高微孔隙和小孔隙所占的比例。生物炭的添加降低了该粉黏壤土的饱和含水率和凋萎系数。细炭对粉黏壤土的田间持水率没有显著影响,粗炭降低了粉黏壤土的田间持水率。两种粒径的生物炭均可提高粉黏壤土的有效含水率,并降低离心失水过程中土壤的收缩,在这2方面细炭的影响效果比粗炭显著;细炭的添加对粉黏壤土饱和膨胀率没有显著影响,粗炭则降低了粉黏壤土的饱和膨胀率。2种粒径生物炭的添加均降低了该粉黏壤土的饱和水力传导度。3%和6%的添加比例在大部分研究指标中未表现出明显差异。该研究可为生物炭在土壤环境修复应用方面提供一定的理论指导。     

不同砂土和黏土比例对豫中烤烟质量特色的影响

采用池栽方法,在河南宝丰研究了不同砂土、黏土比例对烤烟质量特色的影响。结果表明:烟草各部位干物质的积累量在不同质地土壤上表现为砂质壤土(中质地)黏壤土黏土砂质壤土(粗质地),2/3砂土+1/3黏土处理的烟草各部位的干物质积累量都最大,单叶重则表现为:2/3砂土+1/3黏土1/3砂土+2/3黏土100%黏土100%砂土;烟叶的外观质量、烟叶中化学成分的协调性、香气成分及感官品质及风格特征均以2/3砂土+1/3黏土处理最优。综合来说,2/3砂土+1/3黏土,土壤砂粒比例分别达到50%,粉粒比例达到30%,黏粒比例低于20%最适宜烤烟质量及品质特征的形成。     

不同碎石含量的土壤降雨入渗和产沙过程初步研究

碎石的存在改变了均质土壤的某些物理特性，降雨入渗和侵蚀产沙过程也因此受到影响，获取相关知识有助于模拟和预测土石混合介质中发生的水土过程。试验在模拟降雨条件下，对4种不同碎石含量(质量含量分别为0%，10%，20%和30%)的土壤入渗和产沙过程进行了室内研究。结果表明，碎石含量为10%时，土壤入渗率最大，当碎石含量超过10%时，入渗率反而降低；4种不同碎石含量的土壤侵蚀产沙高峰期均出现在降雨初期0～20 min，此后土壤侵蚀产沙相对稳定且在不同碎石含量的土壤间差别不大；降雨过程中，10%碎石含量的土壤侵蚀含沙率一直保持稳定较低水平，其他碎石含量的土壤侵蚀含沙率起初很高并在0～10 min内急剧下降，此后与10%碎石含量的土壤侵蚀含沙率接近。     

A comparison of the texture of grassland and eroded sandy soils from Shropshire, UK

In previous studies, periodic sampling of topsoils on runoff plots on sandy soils at the Hilton experimental site, Shropshire, UK, suggested erosion decreased the topsoil clay content and increased the coarse fraction. However, a comparison of soil and sediment properties suggested erosion selectively removed sand. Therefore, to cross-check the effects of erosion on soil properties, topsoil samples were collected from bare, eroded runoff plots and compared with samples from adjacent non-eroded grassland. Bare, eroded soil was stonier and particularly deficient in sand compared with grassed soil. Textural differences were very marked in the medium and coarse sands, especially the 0.5–1.0 mm fraction. On the basis of mean properties, the grassed soil was a very slightly stony loamy sand and the bare soil a slightly stony sandy loam. Soil organic matter was significantly less in the bare soils than the grassed soils and thus may have contributed to the higher erodibility of sands in bare soils.     

沂蒙山区不同母岩发育土壤物理性质

以沂蒙山区小圣堂小流域为研究区,对比分析了酸性岩石和钙质岩石发育土壤的物理性质及其影响因素。结果表明:(1)酸性岩石发育土壤石砾及砂粒含量较高,土壤质地由砂壤质到壤砂质,且随土层深度增加,石砾含量增加。钙质岩石发育土壤粉粒及黏粒含量较高,上下两层的土壤颗粒组成相差不大。受成土母岩影响两种土壤分形维数都很低,且酸性岩石发育土壤的分形维数更低。两种土壤石砾含量均大于10%,为粗骨土。(2)酸性岩石发育土壤的容重较大,总孔隙度和毛管孔隙度较小。两种土壤的容重和毛管孔隙度随土层深度的增加而变大,总孔隙度和非毛管孔隙度则反之。毛管孔隙度大小主要受土壤分形维数的影响。(3)酸性岩石发育土壤的饱和导水率大于钙质岩石发育土壤,酸性岩石发育土壤10—20cm土层的饱和导水率较0—10cm土层大,而钙质岩石发育土壤饱和导水率在不同土层深度呈现不规律的变化。土壤质地是影响沂蒙山区土壤饱和导水率的主导因素,其中,砂粒和粉粒含量的影响尤为明显。     

Straw incorporation and soil organic matter in macro-aggregates and particle size separates

Two field experiments in which straw has been removed or incorporated for 17 yr (loamy sand) and 10 yr (sandy clay loam) were sampled to examine the effect of straw on the C and N contents in whole soil samples, macro-aggregate fractions and primary particle-size separates. The particle size composition of the aggregate fractions was determined. Aggregates were isolated by dry sieving. Straw incorporation increased the number of 1–20 mm aggregates in the loamy sand but no effect was noted in the sandy clay loam. Straw had no effect on the particle size composition of the various aggregate fractions. After correction for loose sand that accumulated in the aggregate fractions during dry sieving, macro-aggregates appeared to be enriched in clay and silt compared with whole soil samples. Because of the possible detachment of sand particles from the exterior surface of aggregates during sieving operations, it was inferred that the particle size composition of macro-aggregates is similar to that of the bulk soil. The organic matter contents of the aggregate fractions were closely correlated with their clay + silt contents. Differences in the organic matter content of clay isolated from whole soil samples and aggregate fractions were generally small. This was also true for the silt-size separates. In both soils, straw incorporation increased the organic matter content of nearly all clay and silt separates; for silt this was generally twice that observed for clay. The amounts of soil C, derived from straw, left in the loamy sand and sandy clay loam at the time of sampling were 4.4 and 4.5 t ha^?1, corresponding to 12 and 21% of the straw C added. The C/N ratios of the straw-derived soil organic matter were 11 and 12 for the loamy sand and sandy clay loam, respectively.     

不同土质工程堆积体径流产沙差异

依据野外调查结果概化堆积体下垫面,采用室内人工模拟降雨方法,研究不同雨强(1.0、1.5、2.0、2.5 mm/min)条件下4种砾石质量分数(0、10%、20%、30%)的壤土、黏土及砂土工程堆积体径流产沙特征差异。结果表明:1)砂土堆积体坡面产流开始所需时间较壤土及黏土堆积体长。3种土壤质地工程堆积体含砾石的平均流速较纯土体(砾石质量分数为0)小,大小表现为黏土壤土砂土。砂土堆积体平均径流率较壤土和黏土分别减少20.7%和18.8%;2)砂土堆积体平均侵蚀速率分别是壤土和黏土的3.0和2.3倍。3种土壤质地工程堆积体的平均侵蚀速率随雨强增大递增,但随砾石质量分数递增呈显著线性递减(P0.05);3)砂土堆积体平均侵蚀量分别是壤土和黏土的4.5和3.4倍。3种土壤质地工程堆积体的侵蚀量与径流量和雨强均显著相关。研究成果可为建立生产建设项目工程堆积体水土流失量测算模型提供数据基础和理论依据。     

Nitrogen availability to grain sorghum from organic and inorganic sources on sandy and clayey soil surfaces in a greenhouse pot study

In a greenhouse pot study, we examined the availability of N to grain sorghum from organic and inorganic N sources. The treatments were¹⁵N-labeled clover residues, wheat residues, and fertilizer placed on a sandy clay loam and loamy sand soil surface for an 8-week period. Soil aggregates formed under each soil texture were measured after 8 weeks for each treatment. Significantly greater ¹⁵N was taken up and recovered by grain sorghum in sandy clay loam pots compared with loamy sand pots. Greater ¹⁵N recovery was consistently observed with the inorganic source than the organic sources regardless of soil texture or time. Microbial biomass C and N were significantly greater for sandy clay loam soil compared with the loamy sand. Microbial biomass ¹⁵N was also significantly greater in the sandy clay loam treatment compared to the loamy sand. The fertilizer treatment initially had the greatest pool of microbial biomass ¹⁵N but decreased with time. The crop residue treatments generally had less microbial biomass ¹⁵N with time. The crop residues and soil texture had a significant effect on the water-stable aggregates formed after 8 weeks of treatments. Significantly greater water-stable aggregates were formed in the sandy clay loam than the loamy sand. Approximately 20% greater water-stable aggregates were formed under the crop residue treatments compared to the fertilizer only treatment. Soil texture seemed to be one of the most important factors affecting the availability of N from organic or inorganic N sources in these soils.Contribution from the MissouriAgricultural Experiment Station, Journal Series No.12131     

容重对土壤水分入渗能力影响模拟试验

通过人工改变土壤颗粒级配,配制典型砂壤、中壤、黏壤,并设置不同容重水平,用土柱积水入渗模拟了土壤容重对其入渗能力的影响,为土壤改良和促进天然降水转化利用提供理论依据。结果表明,容重对土壤入渗能力有较大影响。试验土壤入渗能力随容重增大递减,3种典型土壤稳定入渗速率与容重均呈对数负相关,砂壤120 min累积入渗量与容重呈幂函数负相关,中壤、黏壤则呈线性负相关。考斯加科夫入渗模型中,表征初始入渗速率的参数随容重增大递减,表征入渗能力衰减速度的参数则随容重增大递增,说明土壤初始入渗能力随容重增大递减,入渗能力衰减速度随容重增大递增。     

Survival of Pseudomonas solanacearum biovars 2 and 3 in soil: Effect of moisture and soil type

The survival of Pseudomonas solanacearum biovars 2 and 3 in three soils, a Nambour clay loam, a Beerwah sandy loam and a Redland Bay clay, was compared at pressure potentials of ?0.003, ?0.05 and ?0.15 kPa. The soils were inoculated with mutants of P. solanacearum biovars 2 and 3, resistant to 2000 μg streptomycin sulphate ml^?1 and their survival measured every 6 weeks for 86 weeks in the clay loam and clay and for 52 weeks in the sandy loam. Soil populations declined with the initial drying necessary to bring the soil moisture to the specific pressure potentials; the initial counts for biovar 2 varied between 0.20 and 2.00 × 10⁹ cfu g^?1 soil and for biovar 3 between 0.17 and 1.29 × 10⁹ cfu g^?1 soil.The population decline in soil maintained at a constant pressure potential was expressed as the rate of population decline. Biovar 2 declined more rapidly than biovar 3. The rate of population decline of each biovar at ?0.003 and ?0.05 kPa was greater in clay loam than in sandy loam and at all pressure potentials it was greater in clay loam and sandy loam than in clay. There was also a tendency for the rate of population decline of both biovars to decrease in the drier soil treatments.     

不同质地耕层土壤有效态微量元素含量特征

[目的]研究不同土壤质地下耕层土壤有效态微量元素含量特征,为合理制定农田土壤施肥方案和提高土壤养分资源利用率提供依据。[方法]以库车县不同质地耕层土壤(0—20cm)为调查对象,采用统计方法对土壤微量元素有效态含量特征进行分析。[结果](1)土壤有效态微量元素在壤土、砂壤土、黏土、黏壤土及砂土中含量差异显著(p0.05),且壤土和砂壤土的有效态微量元素含量相对较高;(2)土壤微量元素有效性综合指数排列顺序依次为:砂壤土(1.51)砂土(1.44)黏土(1.42)壤土(1.41)黏壤土(1.27);(3)土壤有机质与土壤有效态微量元素均具有极其显著的相关性(p0.01),pH值则与有效铜和有效锰相关显著(p0.05)。[结论]在不同土壤质地下,微量元素铁和锌含量较为缺乏,锰和铜含量则相对较为丰富,故应依据这一特性进行土地科学管理和施肥。     

土壤原始颗粒对不同破碎机制下团聚体稳定性的影响

土壤团聚体是土壤结构的基本单元,其稳定性是描述土壤抵抗外力破坏作用的重要指标。目前常用的团聚体测定方法很少考虑到土壤原始颗粒对其不同破碎机制下稳定性的影响。以两种不同质地团聚体特征差异明显的壤质砂土和砂质黏壤土为研究对象,对土壤全样进行快速湿润(FW)、预湿润后震荡(WS)以及慢速湿润(SW)三种处理方式预处理以研究团聚体不同破碎机制,同时考虑将各粒级团聚体中的土壤原始颗粒剥离出来,消除土壤原始颗粒对各粒级团聚体含量结果的影响,研究土壤原始颗粒对不同破碎机制下团聚体稳定性的影响。结果表明:两种土壤在不同处理方式下,各粒级土壤含量存在较大差异,砂质黏壤土在三种处理模式下平均质量直径(MWD)均显著大于壤质砂土,两种土壤MWD均呈现MWD_(fw)MWD_(ws)MWD_(sw)的大小顺序,两种土壤团聚体破坏均是团聚体快速湿润时孔隙内部封闭的空气压力作用为主,其次是机械扰动作用,黏粒膨胀作用影响最小。土壤原始颗粒对各粒级团聚体的影响程度受到土壤类型和破碎机制影响,土壤原始颗粒对壤质砂土影响较大,对砂质黏壤土的影响相对较小。分散前的团聚体(0.05 mm)占总土壤的百分比(AR)值难以正确反映土壤团聚体稳定性,消除土壤原始颗粒影响后,AR能够较好体现土壤团聚体稳定性。消除土壤原始颗粒影响前后的AR比值表明土壤原始颗粒对壤质砂土的影响远远大于对砂质黏壤土的影响。