Impact of sugar industry effluents on soil cellulase activity

An assessment on the impact of sugar industry wastes on soil physicochemical and cellulase activity in waste dump sites, carried out in urban Nandyal, Southern India. Some core samples were collected from the selected profile pits at different soil horizons of dump (test) and non-dump sites (control). The experimental results indicated that, most of the physicochemical properties such as silt, clay, electrical conductivity, water holding capacity, organic matter and total nitrogen contents, microbial population and cellulase activities were significantly higher in the test sample than in the control. Furthermore, though the application of effluents substantially increased the cellulase activity, but was declined at high effluent concentration. Nevertheless, enzyme activity was gradually dropped upon prolonged incubation period in all three samples, such as control, test and effluent amended samples.     

Physico-chemical properties and productivity of a Nigerian Typic-Haplustult amended with fresh and burnt rice-mill wastes

In order to arrest the declining productivity of the soils in the Abakaliki agro-ecological zone of S.E. Nigeria, four levels (12.5, 25.0, 37.5 and 50.0 Mg ha-1) of fresh (FW) and burnt (BW) rice-mill wastes abundant in the area, and a mixture of the waste + NPK and NPK alone were added to the soil (Typic-Haplustult) to evaluate their immediate and residual effects on the productivity of the soil using maize (Zea mays L.) as a test crop. Results showed a significant reduction in bulk density as well as improvements in total porosity and water stable aggregates (WSA > 0.5 mm) at levels > 12.5 Mg ha-1 of the FW amendments. Although both amendments failed to improve the soil pH, significant improvements in soil C, N and BS were obtained at 37.5 Mg ha-1 and above in both amendments. The highest relative increase (TF) of 135.1% and 102.8% in C and N in the first season and 94.4% and 99.3% in the second season were obtained in the FW at 50.0 Mg ha-1. The highest maize grain yields of 2.74 and 2.66 Mg ha-1 were obtained in the waste + NPK mixtures (FW/BW + NPK) in the first season. The residual yield was highest (1.45 Mg ha-1) in the FW amendment at 50.0 Mg ha-1. The results showed that regular and properly planned applications of these wastes can sustain the productivity of soils in this region.     

三峡山地不同类型植被和坡位对土壤水文功能的影响

土壤层下渗和贮蓄水分的水文功能是森林保持水土、涵养水源的基础。以三峡山地大老岭林区为研究区,采集常绿林、落叶林和草地覆盖下不同坡位的原状土样,测定其饱和导水率和水分特征曲线,分析植被类型和坡位对土壤水分参数和库容的影响。结果表明:常绿林地的入渗性能最好,饱和导水率为7.80—322.81 cm/d,大于落叶林地(0.33—137.03 cm/d)和草地(0.84—115.80 cm/d);坡位间差异表现为上坡高于下坡。不同样地的饱和含水量差异较小,但毛管持水量和田间持水量差异明显,草地最大,为20.77%—50.39%;不同坡位比较表现为下坡高于上坡。不同样地土壤水库容量差异较大,由田间持水量得到的库容量占总库容量的百分比以草地最大(63.25%),其次是落叶林地,常绿林地最小;坡位上表现为下坡的田间持水库容大于上坡。饱和导水率与土壤总孔隙度、有机质含量呈显著正相关,与容重呈显著负相关;饱和含水量、毛管持水量、田间持水量均与土壤总孔隙度、有机质含量和粉粒含量呈显著正相关,与容重、砂粒含量呈显著负相关。综合以上,草地持水性能最强,利于保蓄水分,常绿林地最弱,更利于水分入渗,补给地下水,下坡位的持水性能强于上坡位。     

五节芒对重金属污染土壤微生物生物量和呼吸的影响

选择3个五节芒在重金属污染地的定居点作为研究样地,其中两个为Pb/Zn矿尾矿砂堆积地（W：黄岩铅锌尾矿;Y：三门铅锌尾矿）,一个为冶炼厂附近污染农田（N）,分别测定其根围与根际土壤微生物基础呼吸、微生物量碳、微生物量氮、土壤理化特性和土壤重金属含量.结果表明：根际土壤微生物基础呼吸和微生物量氮均显著地高于根围土壤（P<0.05）,除了N样地外,微生物量碳在根围与根际之间差异不显著（P>0.05）.根际土壤有机碳、总氮（Y样地除外）和离子交换量（N样地除外）低于根围土壤.根际重金属（Pb、Zn、Cu、Cd）总量与DTPA（二乙三胺五乙酸）可提取量普遍低于根围土壤.冗余分析（RDA）表明,根围和根际土壤微生物与土壤理化特性呈不同程度的正相关,而与土壤重金属含量呈现不同程度的负相关.主分量及回归分析同样证明土壤微生物总体变化与土壤理化特性呈正相关（根围R²=0.653;根际R²=0.690）,而与重金属含量呈负相关（根围R²=0.610;根际R²=0.662）.     

Effect of the application of town refuse compost on the soil-plant system: A review

This paper reviews the currently available information concerning the use of town refuse compost as a potential fertilizer. Many studies have generally shown that the application of this material has promoted a positive influence on a wide variety of craps. Nevertheless, contradictory results of crop yields have been obtained when the fertilizing capacity of compost has been contrasted with those of organic and mineral fertilizers. It has been demonstrated that the application of compost to soil improves some physical properties such as porosity, water-holding capacity and bulk density. It also promotes buffering capacity of soil and increases the percentage of organic matter and cation exchange capacity. Occasionally, negative aspects can emerge from compost incorporation, such as an increase in organic pollutants and electrical conductivity of soils. In general, compost application to soil has a positive effect on the microbial population and rhizosphere microorganisms and also contributes to the reduction of nemotode populations in plants. However, when big doses of compost are used, an inhibitory effect on seed germination may appear. The nitrogen availability of the municipal compost is closely related to the maturity of this material. A wide range of results has been obtained from different studies performed to evaluate the efficiency of compost as a source of phosphorus, sulphur, calcium and magnesium for plants. The incorporation of municipal compost constitutes a valuable resource for supplying potassium and some micronutrients (i.e. boron and zinc), but also presents potential pollution hazards associated with some heavy metals.     

Sedimentary Residual Soil as a Waste Containment Barrier Material

Compacted soil liners are widely used as a waste containment barrier to control or restrict the migration of contaminant/leachate from the landfill into the environment because of their low hydraulic conductivity, attenuation capacity, resistance to damage or puncture, and cost effectiveness. Compacted soil liners are usually composed of natural inorganic clays or clayey soils. If natural clayey soils are not available, kaolinite or commercially available high swelling clay (bentonite) can be mixed with local soils or sand. This study examines the potential of a sedimentary residual soil as a waste containment barrier in landfills. The laboratory experiments conducted were: grain size distribution, Atterberg limits, swelling tests, compaction, volumetric shrinkage strain, unconfined compression, hydraulic conductivity and cation exchange capacity. The experimental results were compared with those recommended by various researchers for evaluation of its suitability. Test results showed that the soil compacted with modified Proctor compaction effort possesses low hydraulic conductivity (≤1 × 10^?7 cm/s) and adequate strength. In addition, compacted sedimentary residual soil exhibited little volumetric shrinkage strain of below 4% at this compaction effort. Thus, the sedimentary residual soil could be effectively used for the construction of a waste containment barrier in landfills.     

Soil quality around a solid waste dumpsite in Port Harcourt, Nigeria

The levels of soil parameters and selected heavy metals around a solid waste dumpsite receiving untreated wastes from all sources and a control site within Port Harcourt, Nigeria have been examined. Top soil (0–15 cm) and sediment samples were collected and analysed for pH value, particle size, total nitrogen, potassium, available phosphorus, organic matter, effective cation exchange capacity, cadmium, nickel and lead using standard methods. The results showed that the waste dump contributed to the high levels of nutrients and heavy metals. The dry season mean concentrations were: organic matter (5.28 ± 1.34% or 132,422.4 kg ha^?1), K (1.60 ± 0.52 meq per 100 g), N (0.09 ± 0.06% or 2257.2 kg ha^?1), Av.P (15.11 ± 7.57 μg g^?1), Cd (1.34 ± 0.72 μg g^?1), Ni (4.10 ± 1.63 μg g^?1) and Pb (38.85 ± 22.18 μg g^?1) while the wet season mean concentrations were organic matter (5.46 ± 1.39% or 136,936.8 kg ha^?1), K (2.79 ± 0.81 meq per 100 g), N (0.10 ± 0.05% or 2508 kg ha^?1), Av.P (9.22 ± 2.69 μg g^?1), Cd (1.72 ± 1.22 μg g^?1), Ni (14.95 ± 14.94 μg g^?1) and Pb (53.50 ± 40.09 μg g^?1). There was efficient mineralization process in the area. The texture of soil on the main dumpsite was loamy sand, which suggests that the ground water in the area is susceptible to contamination by surface pollutants. The texture of soil at the control site is sandy loam while sediment has the textural class of sand. Decomposed organic materials and agricultural activities influenced the texture of soils. The soils from the main dump and sediment were slightly alkaline while the control soil was moderately acidic. In both seasons, a significant variation exists (P < 0.05) between the metal concentrations in soil at the main dump and those in the sediments with a positive correlation (r = 0.572149) in the wet season and (r = 0.956647) in the dry season. The presence of liming materials and activities of microorganisms on the waste dump increased the pH of the soils. The accumulation of nutrients results in the luxuriant growth of plants/crops on the waste dump.     

Influences of composted hazelnut husk on some physical properties of soils

Some physical properties of clay loam and sandy loam soils amended with hazelnut husk (HH) were investigated. HH collected from hazelnut trees were dried, ground and composted for four months. Before use the composted material obtained was separated to three different aggregate sizes, smaller than 0.84 mm, 0.84-2.38 mm and bigger than 2.38 mm. Then these fractions were mixed with soil samples, at 0%, 1%, 2%, 4% and 8% by weight.Huzelnut husk compost-soil mixtures were placed to plastic pots and kept in an incubator at 25+/-5 degrees C for 45 and 90 days. At the end of incubation periods, water stable aggregate (WSA), hydraulic conductivity, total porosity, aeration porosity and macro- and micro-pore percentages of the mixtures were determined. Results obtained showed that composted HH increased the WSA, hydraulic conductivity, total porosity and macro-pore percentage in both clay loam and sandy loam soils depending on the incubation time and aggregate sizes.     

DGGE fingerprinting of bacteria in soils from eight ecologically different sites around Casey Station,Antarctica

Bacterial community structures in soils collected from eight sites around Casey Station, Antarctica, were investigated using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA gene fragments. Higher bacterial diversity was found in soils from protected or relatively low human-impacted sites in comparison to highly impacted sites. However, the highest diversity was detected in samples from Wilkes Tip, a former waste disposal site that has been undisturbed for the last 50 years. Comparison of community structure based on non-metric multidimensional scaling plots revealed that all sites, except the hydrocarbon-contaminated (oil spill) site, were clustered with a 45% similarity. A total of 23 partial 16S rRNA gene sequences were obtained from the excised DGGE bands, with the majority of the sequences closely related to those of the Cytophaga–Flexibacter–Bacteroides group. No significant correlation was established between environmental variables, including soil pH, electrical conductivity, carbon, nitrogen, water content and heavy metals, with bacterial diversity across the eight study sites.     

Soil hydraulic properties as ecological indicators in forested watersheds impacted by mechanized military training

Soil hydraulic properties were characterized on a ridgetop training site and other sites not impacted by training at Fort Benning, a military installation in southwestern, GA to: (1) examine the influence of mechanized training on soil hydraulic properties and (2) evaluate the utility of soil hydraulic properties as disturbance-level indicators related to ecosystem integrity. Ridgetop surface soils impacted by mechanized military training exhibited a reduction in the mean pore size, as indicated by smaller scaling factors, an increase in the soil bulk density and a decrease in saturated hydraulic conductivity for training locations versus non-training locations. Soil bulk density, saturated hydraulic conductivity and scaling factors exhibited lower population variance in the training sites, indicating repetitive training cycles that progressively mix and homogenize the soil. Surface soils (0–3 cm below ground surface) at all sites were predominantly loamy sands. The observed differences in measured soil properties at training and non-training sites characterize the endpoints of an ecosystem disturbance gradient where relatively un-impacted forest transitions to barren, churned sand. They also help explain the visual evidence of increased overland flow and significant soil erosion in the training areas. While results from this research showed a marked difference in measured soil properties between the two extreme types of land management, more work is needed to establish threshold levels for soil properties related to mechanized vehicle training cycles and training intensity and corresponding ecosystem degradation/integrity. It is noted that for assessment of immediate erosion potential and ecosystem integrity, remote sensing techniques paired with watershed-scale numerical modeling may be more valuable and that greater research emphasis be given to characterizing the indirect, yet more widespread, down-slope impacts of mechanized training activities localized on the ridgetops.     

煤矿复垦区土壤水动力学特性对下渗过程的影响

煤矿复垦区土壤水对植物生长、溶质运移以及土壤环境的变化起着至关重要的作用。定量揭示煤矿复垦区土壤水下渗过程是亟待诠释的关键科学问题。本研究通过测定典型矿区不同深度土壤非饱和导水率、容重、总孔隙度和粒径等水动力学参数,结合染色示踪试验,刻画矿区非饱和带土壤水运移过程。染色示踪结果显示30、60 L和90 L这3种实验下渗水量条件下,水流沿X方向侧向扩散的最大距离分别为10、30 cm和35 cm,沿Y方向侧向扩散的最大距离分别为10、25 cm和30 cm。互相关函数显示随着下渗水量增大,水流扩散作用也在加强,但过多水量并没有明显增加下渗深度和扩散距离。吸力大于300 hpa时,0.01—0.05 mm土壤粒径含量和非饱和导水率呈负相关关系;吸力和非饱和导水率采用指数函数拟合效果较好(r~20.9),对拟合参数a、b和土壤容重(x)进行回归分析:a=0.0015x~2-0.00499x+0.0004,b=0.0583x~2+0.1234x-0.072。同一吸力下土壤容重大的土样非饱和导水率较小;吸力值为300 hpa是非饱和导水率的转折点;非饱和导水率和土壤容重呈现负相关关系,和总孔隙度呈现正相关关系,且二者的相关性随吸力的增加而降低。     

子午岭植被恢复对土壤饱和导水率的影响

通过对子午岭林区不同植被的土壤性质进行实验室测定和野外调查,对饱和土壤水分运动的重要参数之一土壤饱和导水率(Ks)及其相关因子进行了多元分析和通径分析,揭示了植被恢复提高土壤水分传输性能的机理,主要结论如下:土壤有机质是子午岭林区九种植被下土壤饱和导水率提高的主要驱动因子.不同植被下的土壤饱和导水率均随深度的增加而迅速降低,尽管草地和先锋草地在5～10cm深度有一强透水层.土壤饱和导水率在剖面上的平均值,从辽东栎、早期森林、灌丛、先锋草地、弃耕地到草地依次降低.灌丛与草地、弃耕地的差异达到显著水平,辽东栎顶级群落的饱和导水率最高,植被的恢复明显提高了土壤饱和导水率.土壤容重、毛管孔隙度、>0.25mm团聚体含量及粘粒含量直接影响土壤饱和导水率.土壤有机质含量的提高能够改善容重、毛管孔隙度、团聚体含量等物理性质.     

Soil physical properties and carbon/nitrogen relationships in stable aggregates under legume and grass fallow

Short-season fallow with legumes and/or grasses can restore the soil organic C and nitrogen (N) and improve soil structure. In this study, we accessed the effects of 2-season legume and grass fallow on structural properties and C/N relationships in aggregates of a sandy loam soil. Two legumes (Calopogonium mucunoides and Centrosema pubescens), and two grasses (Guinea grass (Panicum maximum) and goose grass (Eleusine indica) were used. Results showed that Calopogonium and Centrosema increased soil total porosity and reduced soil bulk densities, while goose grass increased bulk density and reduced total porosity of the soils at 0–15 and 15–30?cm depths. Guinea grass significantly increased the saturated hydraulic conductivity (50.4?cm?h^?1) and water holding capacity of the soils. Aggregates, 4.75 to 0.5?mm were greater in Guinea grass and least in goose grass fallowed soils. Calopogonium increased macro-aggregates at 0–15?cm soils by 48%, and mean weight diameter (MWD) by 44%. Organic carbon in 0.5–0.25?mm and <0.25?mm aggregate sizes was higher in Guinea grass soils. Generally, grasses had 4-fold increases of C:N contents in dry aggregates. In conclusion, short-season fallow with Guinea grass, Calopogonium and Centrosema, increased soil C and N and protected them from losses in stable aggregates.     

Estimating hydraulic conductivity of a sandy soil under different plant covers using minidisk infiltrometer and a dye tracer experiment

The objective of this study was to estimate the hydraulic conductivity of sandy soil under different plant cover at the locality Mláky II at Sekule (southwest Slovakia). Two sites were demarcated at the locality, with mainly moss species at glade site, and pine forest at forest site. The estimation of unsaturated hydraulic conductivity was conducted by (a) minidisk infiltrometer and (b) the analysis of a dye tracer total resident concentration. The latter approach assumed the applicability of the stochastic—convective flow theory in the sandy soil. In the dye tracer experiment, two plots (1 × 1 m each) were established in both sites, and 100 mm of dye tracer (Brilliant Blue FCF) solution was applied on the soil surface. Similar results were obtained in both plots, with more than 70 % area of horizons stained in the depth of 30–50 cm. In some cases, the predicted and measured hydraulic conductivity were found within an order of magnitude, thus revealing similar impact of different plant cover on hydraulic properties of sandy soil studied. In contrast to sandy soils used for agriculture, the influence of the plant/surface humus and topsoil interface extended in the form of a highly heterogeneous matrix flow to the depth of 50–60 cm, where it was dampened by horizontal layering.     

Potential mechanisms for achieving agricultural benefits from biochar application to temperate soils: a review

Natural organic biomass burning creates black carbon which forms a considerable proportion of the soil’s organic carbon. Due to black carbon’s aromatic structure it is recalcitrant and has the potential for long-term carbon sequestration in soil. Soils within the Amazon-basin contain numerous sites where the ‘dark earth of the Indians’ (Terra preta de Indio, or Amazonian Dark Earths (ADE)) exist and are composed of variable quantities of highly stable organic black carbon waste (‘biochar’). The apparent high agronomic fertility of these sites, relative to tropical soils in general, has attracted interest. Biochars can be produced by ‘baking’ organic matter under low oxygen (‘pyrolysis’). The quantities of key mineral elements within these biochars can be directly related to the levels of these components in the feedstock prior to burning. Their incorporation in soils influences soil structure, texture, porosity, particle size distribution and density. The molecular structure of biochars shows a high degree of chemical and microbial stability. A key physical feature of most biochars is their highly porous structure and large surface area. This structure can provide refugia for beneficial soil micro-organisms such as mycorrhizae and bacteria, and influences the binding of important nutritive cations and anions. This binding can enhance the availability of macro-nutrients such as N and P. Other biochar soil changes include alkalisation of soil pH and increases in electrical conductivity (EC) and cation exchange capacity (CEC). Ammonium leaching has been shown to be reduced, along with N₂O soil emissions. There may also be reductions in soil mechanical impedance. Terra preta soils contain a higher number of ‘operational taxonomic units’ and have highly distinctive microbial communities relative to neighbouring soils. The potential importance of biochar soil incorporation on mycorrhizal fungi has also been noted with biochar providing a physical niche devoid of fungal grazers. Improvements in soil field capacity have been recorded upon biochar additions. Evidence shows that bioavailability and plant uptake of key nutrients increases in response to biochar application, particularly when in the presence of added nutrients. Depending on the quantity of biochar added to soil significant improvements in plant productivity have been achieved, but these reports derive predominantly from studies in the tropics. As yet there is limited critical analysis of possible agricultural impacts of biochar application in temperate regions, nor on the likelihood of utilising such soils as long-term sites for carbon sequestration. This review aims to determine the extent to which inferences of experience mostly from tropical regions could be extrapolated to temperate soils and to suggest areas requiring study.     

典型新建绿地上海辰山植物园土壤水库特征及其影响因子

研究不同植被类型、压实方式和土壤基本理化性质对典型新建绿地上海辰山植物园土壤水库的影响.结果表明:相对自然林地,植物园土壤总库容、滞洪库容、有效库容均较低,但死库容较大,占总库容的60.6%,这导致绿地蓄洪排涝能力减弱.植物园不同植被类型土壤总库容和滞洪库容大小依次为灌木地﹥乔木地﹥草地﹥竹林地﹥裸地,有效库容以灌木和乔木较高,而裸地和竹林地相对较低,裸地和竹林地死库容占总库容的比例最大,分别为65.5%和67.6%.灌木地总库容、滞洪库容和有效库容与裸地差异显著,植被能显著提高土壤的蓄水持水能力,但机械压实和人为践踏显著降低土壤总库容、滞洪库容和有效库容.土壤容重、饱和导水率、毛管孔隙度、非毛管孔隙度、总孔隙度、黏粒和有机质含量显著影响土壤水库,改善土壤理化性质能显著提高城市绿地土壤水库库容.     

Assessing the impact of agro-industrial olive wastes in soil water retention: Implications for remediation of degraded soils and water availability for plant growth

Olive solid waste (OSW) is a toxic by-product of olive oil production. Disposal of OSW is a major problem in many Mediterranean countries leading to increased interest in its potential as an organic fertiliser. Relatively little is known regarding the impact of augmentation with OSW and olive solid waste compost (OSWC) on soil hydraulic properties. The effect of OSW and OSWC on the hydraulic characteristics of common agricultural soils with high sand but very different silt and clay contents was analysed. Increased organic inputs induced reductions in soil bulk density and increases in air capacity, hydraulic conductivity and the water content available for plant growth (AWC) in the Sandy Clay Loam (SCL) soil. Similar patterns were observed in Loamy Sand (LS) soil augmented with OSW, but OSWC caused reductions in hydraulic conductivity, air capacity and AWC. Nonetheless, over longer timescales OSWC may benefit the hydraulic properties of loamy sand soils as the compost becomes fully incorporated within the soil structure. Augmentation with organic olive waste induced the hydraulic parameters of the sandy clay loam soil to become identical to those loamy sand (LS) with a higher available water capacity; suggesting that soil augmentation with OSW and OSWC may be an effective tool in remediating and improving degraded or organic poor soils. In terms of the improvement of hydraulic parameters, application rates of 6–8% OSW/OSWC were most beneficial for both soil types.     

花岗岩崩岗不同部位土壤饱和导水率特征及其影响因素

崩岗是我国南方花岗岩丘陵区普遍存在的水力-重力复合土壤侵蚀现象。为探究崩岗的土壤水力学性质与侵蚀机理的内在联系及其与影响因素之间的关系,选择桂东南活动型、半稳定型和稳定型3种花岗岩崩岗为对象,研究不同部位土壤饱和导水率的空间变化及其影响因素。结果表明:1)崩岗土壤饱和导水率在不同部位呈波动分异,其中崩壁中部为最小值,崩积堆上部为最大值,其次为洪积扇顶端。2)选取Cosby、Compbell、Julià、Hypre 4种土壤饱和导水率传递函数对该区土壤饱和导水率进行拟合,结果预测值与实测值均存在偏差。3)相关性分析表明,土壤饱和导水率与毛管孔隙度、黏粒含量呈极显著负相关关系,与非毛管孔隙和砂粒含量呈极显著正相关关系。4)通径分析表明,砂粒含量为崩岗土壤饱和导水率的主要影响因素,其次为非毛管孔隙度和土壤容重,其中砂粒含量与非毛管孔隙度对土壤饱和导水率呈正效应,容重呈负效应。研究结果可为揭示崩岗侵蚀机理和防治提供理论依据。     

油页岩废渣场植物修复的生态效应

对广东茂名页岩油工业固体废物裸露灰渣地植林18a(南排)和3-5a(北排)后的植物生长、凋落物、土壤容重、有机质、pH和植物多样性进行了对比调查和分析。结果表明,南排和北排已形成了森林环境。土壤基质已得到了改善,南排的凋落物现存量增加了1.39倍,土壤有机质增加了52.39%(0-20cm)、50%(20-40cm),土壤pH值提高了0.28个单位。南、北排林地土壤pH值分别比植林前裸地提高了0.99个单位和0.71个单位。这说明植树造林对增加土壤有机质效果明显,对提高土壤pH值则相对较慢。南排自堆放油页岩灰渣后,45a来入侵定居的野生植物有48科118属138种,其中草本植物占总种数的54%,乔木15种;北排堆放28a来,有24科63属66种植物入侵定居,其中草本种类占67%。     

湖南双季稻种植区不同生产力水稻土的物理性质

在湖南省东部、中部和西北部8个水稻主产县采集了24个不同生产力水稻土样品,测定了土壤物理性质和黏土矿物组成参数,包括土壤容重、土粒密度、孔隙度、田间持水量、水稳性团聚体、平均质量直径、标准化质量直径、团聚体破坏率、田间持水量、有机碳、有机胶结物质、无机胶结物质和黏土矿物等指标,以研究湖南省双季稻种植区不同生产力水稻土物理性质的差异.结果表明：高产水稻土（>14000 kg·hm^-2）的容重小于1.2 g·cm^-3,总孔隙度大于50%,通气孔隙度多数大于4%,0.5～5mm水稳性团聚体含量多数在20%以上.高产水稻土与中产水稻土(10000～13500 kg·hm^-2)之间的多数物理性质无显著差异,但与低产水稻土(<10000 kg·hm^-2)的差异显著,说明中产水稻土只要在良好的管理条件下可以转变为高产水稻土;而低产水稻土的物理性质较差,应重视这类水稻土的改良.