基于CT分析露天煤矿复垦年限对土壤有效孔隙数量和孔隙度的影响

露天煤矿排土场由于排土过程中大型机械压实等作用会对土壤的孔隙结构产生影响,重构适合于植被生长的土壤孔隙结构是排土场土地复垦的重要工作。为对排土场重构土壤孔隙结构进行定量分析,该文采用高精度无损计算机断层扫描技术（CT）对山西平朔矿区安太堡露天煤矿排土场平台全黄土母质覆盖的不同复垦年限（0、20、23 a）以及原地貌的土壤进行分层扫描成像,并利用Photoshop和Arcgis软件对扫描图像进行处理和统计分析,探讨了排土和复垦对土壤孔隙数量和孔隙度的影响,分析了排土场重构土壤大、中和小孔隙的变化。结果表明：原地貌土壤孔隙数量和孔隙度最大,其次是复垦23和20 a的土壤,排土后未复垦土壤孔隙数量和孔隙度最小。采矿和排土等活动由于大型机械压实作用降低了土壤孔隙数量和孔隙度,尤其是大孔隙数量和大孔隙度;土地复垦对增加土壤孔隙数量和孔隙度有一定的作用,但是过程比较缓慢。采矿和排土等活动对表层土壤孔隙数量和孔隙度的影响要高于底层土壤。该研究可为黄土区大型露天煤矿排土场重构土壤结构的优化与土地复垦措施选择提供依据。     

Microbial community structure and relationship with physicochemical properties of soil stockpiles in selected South African opencast coal mines

At present, there is no comprehensive soil quality assessment practice for soil stockpiles in the South African coal mining industry. Soil microorganisms and enzymes are suitable indicators for soil quality monitoring. Therefore, this study investigated the microbial community and enzyme (beta-glucosidase and urease) activities in soil stockpiles of opencast coal mines in the coal-rich region of South Africa. Soil stockpiles of three opencast coal mines were sampled at depths of 0–20 cm (‘topsoil’) and >20 cm (‘subsoil’) across three seasons. Beta-glucosidase and urease activities were mostly higher in soil stockpiles than in unmined soils and were significantly influenced (P < 0.05) by the interaction of site and seasonal factors. However, analyses of PCR-denaturing gradient gel electrophoresis (PCR-DGGE) profiles of partial 16S rRNA gene and internally transcribed spacer 2 (ITS2) sequences revealed higher microbial diversity in unmined (reference) soils compared to soil stockpiles across all seasons. Redundancy analysis further revealed that microbial communities of topsoil were not significantly (P > 0.05) influenced by soil properties, whereas microbial communities of subsoils were significantly (P < 0.05) influenced by pH, organic carbon, total nitrogen and phosphorus contents. Furthermore, operational taxonomic units (OTUs) belonging to genera of known phytobeneficial species such as Azomonas, Aureobasidium, Phialocephala, Phoma and Sordariomycetes were detected in these soils. Overall, results suggest that the microbial community structure and diversity observed in stockpiles is impaired (compared to the unmined site), although variations in the microbial community structure of soil stockpiles across seasons are site-specific. The impaired microbial community of stockpiles may have negative implications on soil biological processes driven by microbes; especially those that are critical for nutrient cycling and ecosystem sustainability. More importantly, such alteration in soil biodiversity may impair post-mining land use capability of stockpile soils.     

生物炭添加对矿区压实土壤水力特性的影响

中国黄土高原大型露天煤矿开采导致土壤质量下降,生物炭作为环境友好型土壤改良剂,在改善农田土壤质量中应用广泛,但在有关矿区压实土壤改良的研究中不够深入。为此,该研究通过室内试验分析不同粒径的生物炭在不同添加量下对矿区排土场压实土壤水力特性的影响。试验采用4种粒径（>1～2、>0.25～1、0.10～0.25、<0.10 mm）与4种添加量（0、4、8、16 g/kg）的生物炭,设计5种压实条件（容重分别为1.3、1.4、1.5、1.6、1.7 g/cm3）,并利用van Genuchten模型（VG模型）拟合土壤水分特征曲线。结果表明,添加生物炭后土壤水分特征曲线的相关系数均在0.960以上,标准差均小于0.015,说明VG模型适用于拟合添加生物炭后的土壤水分特征曲线。随着生物炭添加量的增加,土壤孔隙分布明显改变,形成了大量大孔隙和中孔隙,土壤的持水能力提高。在低容重（1.3、1.4 g/cm3）条件下,生物炭粒径越大（0.25～2 mm）添加量越高（8、16 g/kg）,土壤持水、保水效果越明显;在高容重（1.5、1.6、1.7 g/cm3）条件下,小粒径（<0.25 mm）和较低的生物炭添加量（4、8 g/kg）则表现出较好的持水能力。对于不同压实条件的排土场土壤,有针对性地施用生物炭,将有效提高土壤持水保水能力,提高土壤中植物的有效利用水分。     

Soil macropore characteristics and aggregate stability with poly-γ-glutamic acid amendment under wetting–drying cycles

Soils are typically subjected to multiple wetting–drying (WD) cycles due to irrigation and seasonal climate cycles, which directly impact soil pore structure and soil aggregate stability. Poly-γ-glutamic acid (γ-PGA) is a polymer used to improve soil water holding capacity and plant growth. However, the impact of γ-PGA on soil pore structure requires further research, particularly under WD cycles. Therefore, we investigated the different amounts of γ-PGA on soil structure, including soil aggregate stability, macropore (>100 μm) structure characteristics and the relationship between macropore characteristics (equivalent pore diameter, pore shape factor, soil porosity, fractal dimension (FD), soil connectivity and the percentage of aggregate content with particle size larger than 0.25 mm) and soil aggregate stability by structural equation modelling (SEM) under WD cycles. A sandy soil and a loam soil were studied, and amended with γ-PGA at three different concentrations: 0 (P0), 0.4% (P4) and 0.8% (P8) (w/w, %). Results showed that γ-PGA amendment increased the mean weight diameter (MWD) and the percentage of aggregate content with particle size larger than 0.25 mm (R_0.25) under WD cycles in both sandy and loam soils, while the MWD between P4 and P8 did not differ significantly. As the number of WD cycles increased, soil porosity (TP) increased due to an increase in pores of 100–500 μm. With γ-PGA added to soil, large microporosity (>1000 μm) increased in sandy soil, but decreased in loam soil. In addition, 8WD cycles also increased the FD (2.6%–4.2%) and pore connectivity (Con) compared with 4WD. Structural equation modelling (SEM) revealed that soil pore characteristics accounted for 74% and 98% of the variation in sandy and loam soils, respectively. TP, FD, Con and R_0.25 directly contributed to MWD, according to the SEM. These findings improve our understanding of pore characteristics and aggregate stability, which are key factors influencing soil quality when amended with γ-PGA during the seasonal WD period.     

Water retention characteristics of soils with double porosity

A soil with double porosity is modelled as a collection of aggregated particles, in which a single aggregate is made up of discrete particles bonded together. Separate fractal distributions for pore sizes around and within aggregates are defined. The particle size distribution of the double porosity soil is also modelled using a fractal distribution, which may have a fractal dimension very different to those defining the pore sizes. The surface areas of the particles and the pores within the aggregates are assumed to be equal, enabling an expression linking two fractal dimensions to be defined. It is necessary to introduce ratios between maximum and minimum particle and pore sizes into the expression. A theoretical soil‐water characteristic curve is then derived for a double porosity soil. The curve, and the underlying assumptions regarding the distributions of pore and particle sizes, showed good agreement with experimental data for a range of soils having double porosity. A discontinuity is observed in the soil‐water characteristic curve at a second air entry value related to the maximum pore size within the aggregates, a feature also observed in experimentally obtained soil‐water characteristic curves for double porosity soils.     

利用计算机断层扫描技术研究土壤改良措施下土壤孔隙

为探明不同土壤结构改良措施（秸秆覆盖、免耕、有机肥、保水剂）对土壤孔隙特征及分布的影响,采用计算机断层（computed tomography,CT）扫描法定量分析了土壤孔隙的数目、孔隙度及孔隙在土壤剖面上的分布特征。结果表明：不同措施均提高了土壤总孔隙数、大孔隙数及0.13～1.0 mm孔隙数,且其孔隙度也相应提高。同时孔隙成圆率也得到了改善。各处理中以有机肥和免耕处理效果较佳,其次为保水剂和秸秆覆盖,对照最低。此外,不同措施显著提高了土壤的田间持水量和＞0.25 mm 水稳性团聚体含量,降低了土壤容重,且各处理中,仍以有机肥和免耕处理效果最佳,其田间持水量分别较对照提高了15.9%和16.4%,而土壤容重较对照降低了6.8%和8.8%。相关分析表明：田间持水量、容重和＞0.25 mm水稳性团聚体含量与土壤总孔隙度和大孔隙度呈显著或极显著正相关;而土壤容重对于总孔隙度和大孔隙度及孔隙成圆率呈显著负相关。     

Soil pore-water environment and CO2 emission in a Luvisol as influenced by contrasting tillage

Little is known how contrasting tillage (deep ploughing, top- and sub-soil loosening with straight or bent leg cultivator [BLC], direct drilling [DD]) affect important soil physical properties (total porosity [TP], pore size distribution [PSD], water release characteristics [WRC]) and CO₂ emissions from a Luvisol. The study was aimed to alleviate compaction on land that had been under reduced tillage for 4 successive years. Undisturbed core samples were collected from 5–10, 15–20 and 25–30 cm depths for soil WRCs, TP and pore-size distribution determination. A closed chamber method was used to quantify the CO₂ emissions from the soil. Soil loosening with straight or BLC produced the highest total soil porosity (on average 0.48 m³ m^?3) within 5–30 cm soil layer, while conventional tillage (CT) gave 6%, DD up to 25% reduction. Sub-surface loosening with a BLC was the most effective tool to increase the amount of macro- and mesopores in the top- and sub-soil layers. It produced 21% more macro- and mesopores within 25–30 cm soil layer as compared to the soil loosened with a straight leg cultivator. Plant available water content under CT and DD was lower as compared to that under deep loosening with straight or BLC (23% and 18%, respectively). DD produced 12% lower soil surface net carbon dioxide exchange rate than CT and by 25–28% lower than deep soil loosening with straight or BLC. The increase in micropores within 25–30 cm soil layer caused net carbon dioxide exchange rate reduction. The amount of mesopores within the whole 5–30 cm soil layer acted as a direct dominant factor influencing net CO₂ exchange rate (NCER) (Pxy = ?3.063; r = 0.86).     

氨化秸秆还田对土壤孔隙结构的影响

【目的】土壤孔隙性质是土壤结构性的反映,直接影响着土壤的肥力和水分有效性。定量研究氨化秸秆还田对土壤不同大小等级孔隙数量和孔隙分布的影响,可以为土壤培肥提供科学依据。【方法】采用室内试验方法,设置氨化秸秆加入量为土壤总质量的 0(CK)、 0.384%(S1)、 0.575%(S2)、 0.767%(S3)4个处理,室内培养。在培养0、60、120和180 d,取样测定土壤水分特征曲线(SWRC)数据,利用双指数土壤水分特征曲线模型(DE模型,Double-exponential water retention equation),分析氨化秸秆对土壤剩余孔隙、基质孔隙和结构孔隙的影响; 基于DE模型的微分函数,探究不同氨化秸秆处理对土壤孔隙分布的影响。【结果】不同处理的土壤水分特征曲线SWRC实测值和DE模型模拟值之间的均方根误差介于0.0036和0.0041 cm3/cm3之间,R2介于0.998和0.999之间,土壤含水量模拟值和实测值非常接近1 ∶1,表明DE模型可以准确反映添加氨化秸秆后土壤含水量随吸力的变化规律,较准确地估算土壤不同大小等级孔隙数量变化。培养120 d内,氨化秸秆对土壤剩余孔隙、基质孔隙和结构孔隙影响不显著; 培养180 d时,各处理土壤结构孔隙度表现出随着氨化秸秆添加量的增加而增加的趋势; 此时S3对土壤剩余孔隙影响不显著,显著减小了土壤的基质孔隙度(P0.05),极显著地增加了土壤的结构孔隙度(P 0.01)。在孔隙分布中,氨化秸秆促进了土壤已有孔隙向较大孔隙的发育,显著增加了土壤结构孔隙分布数量; 随着氨化秸秆添加量的增加,土壤结构孔隙的分布数量越大,且峰值出现的越早。氨化秸秆增加了土壤中有机质含量; 土壤结构孔隙和总孔隙均与有机质含量呈显著的正相关关系(P 0.05); 有机质可以黏结团聚土壤的矿物颗粒,有效地促进了土壤结构孔隙的发育; 氨化秸秆对土壤孔隙的影响随着时间的进行越来越明显。【结论】氨化秸秆增加了土壤中有机质含量,促进了土壤孔隙结构的发育,增加了土壤的结构孔隙度和总孔隙度,这对改良和培肥土壤、改善土壤耕性具有重要意义。     

Long-term consequences of topsoil mining on select biological and physical characteristics of two New Zealand loessial soils under grazed pasture

Soil chemical, biochemical, biological and structural properties were measured in two New Zealand loessial soils that were topsoil-mined 10 and 25 years ago respectively. Measurements at the 10-year site were compared to some earlier measurements made at this site and the data combined in a chronological sequence for analysis. Topsoil mining had a large, detrimental impact on the soil microbial biomass, the earthworm populations, easily mineralizable N and soil enzyme activities. However, most of these properties substantially recovered, to 80-90 per cent of the levels in unmined soils, within 10-25 years of restoration under pasture. In contrast, while total soil C and N were less affected by topsoil mining, their recovery was much slower. Stabilities of macro-aggregates of soil had fully recovered within 10-25 years after topsoil mining. The apparent changes in all the measured properties between 10 and 25 years of restoration were small in comparison with changes between 0-10 years of restoration after topsoil mining. The total C content of both soils under pasture appeared unlikely to attain the levels present in unmined soils. In soils undergoing restoration, the ratio of microbial C/total soil C may be a useful index of soil ‘biological stability’. Sulphatase activity may reflect the recovery of pasture production.     

Land restoration management after topsoil mining and implications for restoration policy guidelines in New Zealand

A three-year field trial on an upland loessial soil (Belmont silt loam) in New Zealand investigated the effects of ripping, application of fertilizer N and grazing management on the recovery of some physical, chemical and biochemical properties of soil and pasture productivity following removal (mining) of topsoil. Removing the top 31 cm of soil by mining (all of the A horizon and part of the AB horizon) also removed most of the soil's labile organic matter fractions, and to a lesser extent its total organic matter. After three years, the microbial C and mineralizable N in the 0–10 cm depth of mined soil had reached 65 and 62 per cent of the corresponding levels in unmined soil. Ripping to a depth of 30 cm, application of fertilizer N and lenient grazing of the pasture failed to enhance the recovery of soil fertility. A soil sampling depth of 20 cm provided a reasonable basis to assess the microbial biomass and potential fertility. Pasture productivity was, on average, 30 per cent lower on mined land than on unmined land over the first three years after mining. Application of N proved uneconomic in terms of farm production, although a good pasture response to N fertilizer was obtained. The results from this and related trials are summarized as a series of recommendations for the monitoring and regulation of topsoil mining. An incentive regime is also recommended to encourage land owners and/or topsoil miners to use successful restoration techniques on topsoil-mined land. Copyright © 1999 John Wiley & Sons, Ltd.     

西南喀斯特区砾石对石灰土土壤孔隙及水分入渗的影响

[目的] 砾石是影响土壤孔隙和水分入渗的重要因素,明确砾石通过改变哪些土壤孔隙特征进而影响水分入渗具有重要意义。[方法] 以西南喀斯特地区砾石含量高的石灰土为研究对象,采用CT扫描和室内一维土柱入渗试验,对比分析2种砾石粒径(2.0~5.0,5.0~12.5 mm)和5种砾石含量(0,10％,20％,30％,40％)条件下的土壤孔隙特征及水分入渗特性,并使用结构方程模型探究土壤孔隙特征与入渗特性之间的耦合关系。[结果] (1)含砾石土壤的大孔隙度、孔隙连通率、孔隙形状因子、孔隙表面积和孔隙体积均高于无砾石土壤;且当砾石含量为20%和30%时,孔隙连通率与孔隙形状因子和无砾石土壤之间存在显著性差异(p<0.05);(2)砾石改善土壤入渗性能,粒径为2.0~5.0 mm时,砾石含量从10%到40%的稳定入渗率分别是无砾石土壤的4.02,5.00,2.88,5.14倍,累积入渗量分别是1.67,1.76,2.49,2.39倍;粒径为5.0~12.5 mm时,土壤稳定入渗率分别是无砾石的2.20,2.67,4.78,2.78倍,累积入渗量分别是1.42,1.75,2.46,2.02倍。(3)在结构方程模型中砾石含量与孔隙连通率、孔隙等效直径呈正相关关系,孔隙连通率对稳定入渗率的影响最大,孔隙等效直径对累积入渗量的影响最大。[结论] 砾石含量主要通过增加土壤孔隙连通率和孔隙等效直径促进水分入渗,研究结果可为深入认识西南喀斯特地区含砾石土壤的水文过程提供科学依据与理论参考。     

使用自由软件和便携式光学显微镜研究土壤孔隙特征

Total porosity (TP), determined by image analysis, pore type and pore size distribution were evaluated on impregnated soil blocks from an undisturbed Brazilian sandy loam soil using a digital portable optical microscope. The free software Image J (version 1.40g) was used for image analysis. Procedures for soil image collection and analysis were presented. The image analysis allowed the evaluation of pore sizes with diameters ranging from 20 to >1 000 μm. The following types of pores were also obtained: rounded, elongated and intermediate. The results allowed the characterization of the soil as moderately porous (TP=21.6%). Rounded, intermediate and elongated pores were responsible for 11.6%, 31.7% and 56.7% of TP. In relation to pore size 51.1% of TP was in the 100-500 μm size class and a third of TP came from the pores larger than 500 μm.     

Soil organic carbon stock for reclaimed minesoils in northeastern Ohio

Reclamation of disturbed soils is done with the primary objective of restoring the land for agronomic or forestry land use. Reclamation followed by sustainable management can restore the depleted soil organic carbon (SOC) stock over time. This study was designed to assess SOC stocks of reclaimed and undisturbed minesoils under different cropping systems in Dover Township, Tuscarawas County, Ohio (40°32·33′ N and 81°33·86′ W). Prior to reclamation, the soil was classified as Bethesda Soil Series (loamy‐skeletal, mixed, acid, mesic Typic Udorthent). The reclaimed and unmined sites were located side by side and were under forage (fescue—Festuca arundinacea Schreb. and alfa grass—Stipa tenacissima L.), and corn (Zea mays L.)—soybean (Glycine max (L.) Merr.) rotation. All fields were chisel plowed annually except unmined forage, and fertilized only when planted to corn. The manure was mostly applied on unmined fields planted to corn, and reclaimed fields planted to forage and corn. The variability in soil properties (i.e., soil bulk density, pH and soil organic carbon stock) ranged from moderate to low across all land uses in both reclaimed and unmined fields for 0–10 and 10–20 cm depths. The soil nitrogen stock ranged from low to moderate for unmined fields and moderate to high in some reclaimed fields. Soil pH was always less than 6·7 in both reclaimed and unmined fields. The mean soil bulk density was consistently lower in unmined (1·27 mg m⁻³ and 1·22 mg m⁻³) than reclaimed fields (1·39 mg m⁻³ and 1·34 mg m⁻³) planted to forage and corn, respectively. The SOC and total nitrogen (TN) concentrations were higher for reclaimed forage (33·30 g kg⁻¹; 3·23 g kg⁻¹) and cornfields (21·22 g kg⁻¹; 3·66 g kg⁻¹) than unmined forage (17·47 g kg⁻¹; 1·98 g kg⁻¹) and cornfield (17·70 g kg⁻¹; 2·76 g kg⁻¹). The SOC stocks in unmined soils did not differ among forage, corn or soybean fields but did so in reclaimed soils for 0–10 cm depth. The SOC stock for reclaimed forage (39·6 mg ha⁻¹ for 0–10 cm and 28·6 mg ha⁻¹ for 10–20 cm depths) and cornfields (28·3 mg ha⁻¹; 32·2 mg ha⁻¹) were higher than that for the unmined forage (22·7 mg ha⁻¹; 17·6 mg ha⁻¹) and corn (21·5 mg ha⁻¹; 26·8 mg ha⁻¹) fields for both depths. These results showed that the manure application increased SOC stocks in soil. Overall this study showed that if the reclamation is done properly, there is a large potential for SOC sequestration in reclaimed soils. Copyright © 2005 John Wiley & Sons, Ltd.     

Soil development on restored opencast coal sites with particular reference to organic matter and aggregate stability

Abstract. Organic indices and aggregate stability were measured in soils of similar texture on two restored opencast coal sites and on adjacent, undisturbed land in South Wales, UK. The aim was to assess rates of soil change over time, to relate these changes to conditions in undisturbed land and to evaluate organic-aggregation relationships across these range of soils. Several management factors were included in the comparisons.
Organic matter accumulated at the surface (0–7.5 cm) of restored soils, contents being greater than undisturbed soils after 21 years. However, this increase in total organic matter did not result in proportionate increases in carbohydrates and microbial biomass, nor did aggregate stability increase to the degree expected. Between 7.5 and 15 cm depth, rates of change were slower. Microbial metabolic quotient and respiration relative to total soil C were highest in recently (9 years) restored soils, intermediate in 21 year old restored soils and least for undisturbed soils.
Sewage (100t/ha) applied at reinstatement improved clay stability but had little effect on other parameters when measured 9 years later. Drainage of soils restored in 1972 reduced total organic content but its influence on other organic indices was more complex. Carbohydrate contents had the closest association with aggregate stability and microbial biomass.
Although the productivity of restored land may recover more quickly, findings suggest that rehabilitation of normal soil processes following surface mining may take much longer than the normal five year aftercare period.     

黄河三角洲不同土地利用类型土壤微观结构特征

黄河三角洲不同土地利用类型盐碱土微观结构的研究,对认识该地区盐碱土的工程性质和对滨海盐碱地治理具有重要意义。该研究结合粒度分析(particle size distribution,PSD)、X射线衍射(X-ray diffraction,XRD)、压汞(mercury intrusion porosimetry,MIP)和扫描电镜(scanning electron microscopy,SEM)方法,对3种不同土地利用类型盐碱土的微观结构进行定量分析,旨在揭示其微观特性,为黄河三角洲盐碱地治理提供微观理论依据。结果表明:不同土地利用类型下的土壤黏粒含量表现大小依次为农田、滩地、草地,而土壤孔隙度大小依次为草地、滩地、农田;农田、草地与滩地盐碱土矿物成分中,石英、方解石和钠长石等原生矿物占绝对优势,仅含少量黏土矿物,且农田黏土矿物含量远大于草地与滩地;草地与滩地盐碱土孔隙特征类似,两者在0.1≤孔隙直径<10μm范围内小孔隙与微孔隙占有绝对优势,而农田盐碱土以孔隙直径在<2μm范围内的微孔隙与超微孔隙为主。农田盐碱土由致密片状、扁平状结构与微裂隙构成,骨架颗粒间由黏土矿物胶结;草地盐碱土由紧密镶嵌的块状颗粒和架空孔隙构成,骨架颗粒间无胶结;滩地盐碱土由紧密堆积的粒状颗粒和粒间孔隙构成,骨架颗粒间无胶结。研究成果可提高对黄河三角洲不同土地利用类型盐碱土微观结构的认识,为滨海盐碱地的治理、利用和开发提供了微观尺度上的依据。     

保水剂对土壤孔隙影响的定量分析

为探明保水剂不同用量对施入土层土壤孔隙特征及其分布的影响,采用CT扫描法研究盆栽试验条件下小麦收获时的土壤孔隙特征。结果表明:1)施用保水剂均提高了土壤剖面不同土层的土壤孔隙数目、孔隙度和孔隙成圆率。2)随保水剂用量的增加,各土层平均总孔隙数、总孔隙度及成圆率提高;但保水剂用量过高,其总孔隙数增加不明显,总孔隙度和孔隙成圆率降低,但仍高于对照(CK)。3)最终的小麦生物量和籽粒产量表现为54 mg/kg>81 mg/kg>27 mg/kg>CK。因此,施用保水剂改善了土壤孔隙特征,促进了小麦的生长和产量的提高。各处理中以54 mg/kg保水剂用量对于小麦生物量及产量的提高最为显著,分别较对照提高13.1%和22.2%。     

Soil physical properties of afforested and arable land

Abstract. The effects of tree crops on the soil physical properties of former agricultural land were compared with those of ley in a rotation with cereals on adjacent sites. Five sites in southern Sweden were investigated focussing on soil water retention characteristics, dry bulk density, macroporosity and saturated hydraulic conductivity. Three of the sites were on light textured soils and two on clay soils. The tree crops were 30 to 35-year-old hybrid aspen, Populus deltoides , and silver birch, Betula pendula , and the ley crops were one to five years old.
The light-textured soils under tree crops showed bimodal pore size distributions in the macropore region, whereas under ley crops they showed unimodal distributions. Dry bulk densities were generally smaller and the macroporosities larger under tree crops compared with leyicereal crops. Saturated hydraulic conductivities tended to be larger under tree crops. Slopes of the linear regression lines between saturated hydraulic conductivity and each of the parameters dry bulk density, porosity and macroporosity were steeper in the soil under agricultural crops than under tree crops.
Observed differences in physical properties were considered to be an effect of land use, which had brought about changes in aggregate stability, pore size distribution and pore continuity.     

2种典型耕作方式影响下的蔗田土壤孔隙结构及其水分运动特性

为了明确农业生产过程中耕作方式对田间土壤孔隙结构及土壤水分运动特性的影响,以广西农地蔗田为研究对象,基于土壤切片技术分析研究免耕和垄耕2种典型耕作方式蔗田的田间土壤孔隙结构特征,并结合土柱模拟入渗试验,探究土壤孔隙结构对土壤水分运动的影响,进一步揭示孔隙结构与土壤水分运动特性之间的相互作用关系。结果表明：随着土层深度的增加,免耕蔗田孔隙形态以聚集的团块状分布为主,垄耕蔗田孔隙形态以条状分布为主。与免耕蔗田相比,垄耕蔗田的土壤总孔隙度和>2.5 mm孔径的孔隙度分别增加32.5%和21.9%。垄耕蔗田在局部土层深度范围内显著增加上下土层孔隙的变异度(p<0.05),显著降低土壤孔隙的连通性(平均邻近指数为0.448)(p<0.05),土壤孔隙形态相对规则(平均成圆率为0.335)。对于土壤水分运动特性,免耕蔗田总体的土壤饱和导水率和质量流率显著高于垄耕蔗田(p<0.05),初始含水率显著低于垄耕蔗田(p<0.05),质量流率随时间变化强度相对较大,提高水流入渗能力。垄耕降低土壤孔隙结构连通性,使水分蓄存在表层土壤中,一定程度上可降低土壤水分的入渗现象,改变蔗...     

长期施肥对华北农田褐土团聚体微结构与稳定性的影响

为定量分析不同施肥措施对华北农田褐土微观结构及稳定性的影响,该研究依托长期定位施肥试验,集成同步辐射显微CT（SR-μCT）与图像处理技术对不施肥（CK）、氮磷钾肥（NPK）和有机、无机配施（OF）三种处理土壤团聚体微结构及其稳定性进行定量分析,结果表明：经过26 a不同施肥处理,研究区土壤孔隙微结构与稳定性产生了实质性变化,其中长期OF处理土壤孔隙度、大孔隙率、狭长孔隙率、平均孔隙直径、平均弯曲度、孔喉平均表面积及平均质量直径等指标较CK处理分别提升了23.84%、145.71%、21.43%、37.16%、21.3%、51.12%和59.26%,表明长期OF处理显著改善了研究区土壤微结构,提升了团聚体稳定性。长期NPK处理与CK处理土壤团聚体在微结构特征与稳定性方面相似,但大孔隙（等效直径≥500 μm）率均显著低于OF处理（P<0.05）。研究结果可为农业土壤质量评价与保护提供支撑。     

黄土区大型露天煤矿复垦排土场植被恢复立地类型划分——以安太堡露天煤矿为例

露天开采对土地破坏严重,立地条件复杂。只有综合环境因素与植被生态习性,针对不同的立地类型进行植被配置与管护才能达到对矿区生态修复的目的。为此以安太堡露天煤矿西排土场为研究对象,选定58个样点,在样点10 m×10 m范围内对海拔、坡向、坡位、坡度、坡型、覆土基质、覆土厚度、土壤容重、土壤含水量、有机质含量、全氮含量、植被类型组合、归一化植被指数（NDVI）、地面非均匀沉降、河流动能指数、地形起伏度,共18个立地因子进行调查。分析排土场立地条件及特征,运用SPSS聚类分析法对样点进行立地类型划分。最终划分为平台、边坡2个立地小区;平台小区化分为9个立地类型组、13个立地类型,边坡小区化分为9个立地类型组、20个立地类型。研究结果可以为排土场立地改良、植被恢复与维护及生态系统恢复提供依据。