Surfactants and soil water evaporation and migration

1. Water evaporation from soil and sand columns is smaller when the surfactant is placed on the surface, and larger when it is located at the bottom. Water evaporation from soil and sand mixed with the surfactant is as high as without the surfactant. 2. The fact that water evaporation from soil and sand depends on the location of the surfactant in the column is accounted for by the dominant role of migration but not by the suppressive action of the surfactant film on water evaporation. 3. Water migration from sites with surfactant towards sites without surfactant is caused by two pressures: the capillary and the additional pressure arising from the spreading of the surfactant. 4. The importance of the additional pressure on water migration is shown by experiments which rule out the existence of a capillary pressure difference.     

Torfeigenschaften und ungesättigte hydraulische Leitfähigkeit von Moorböden

Peat properties and unsaturated hydraulic conductivity of peat soils . Drainage of organic soils is closely connected with water supply of plants by the capillary fringe of the groundwater. Unsaturated flow of water was measured by the double-membrane apparatus described by Vetterlein, which was modified for experiments with undisturbed peat samples. The influence of decomposition, nature of peat, ash content, bulk density (consolidation) and flux direction on unsaturated flow of water in peat soils was determined. The correlation to unsaturated water conductivity decreased in the sequence: decomposition, flux direction, ash content, bulk density. A dependence on bulk density exists only below pF 2.     

Numerical analysis of soil water dynamics in a soil column with an artificial capillary barrier growing leaf vegetables

An artificial capillary barrier (CB ), which consists of two layers of gravel and coarse sand, was used to improve the soil water retention capacity of the root zone of sandy soil for the cultivation of Japanese spinach (Brassica rapa var. perviridis ). The performance of a CB under specific conditions can be evaluated using numerical simulations. However, there have been relatively few numerical studies analyzing soil water dynamics in CB systems during crop growth. The objectives of this study were (i) to evaluate the performance of a CB during the cultivation of Japanese spinach irrigated at different rates and (ii) to investigate the effect of the irrigation schedule on root water uptake. Numerical analysis was performed using HYDRUS ‐1D after the soil hydraulic properties of the CB materials were determined. In most cases, the HYDRUS ‐1D results agreed well with the experimental soil water content data without any calibration when the dual‐porosity model describing soil hydraulic properties was used for gravel and coarse sand. We found that the dual‐porosity model was able to attenuate the unrealistically steep reduction in the unsaturated hydraulic conductivity predicted by the single‐porosity model. The numerical simulations also showed that the CB played an important role in maintaining plant‐available water in the root zone while maximizing the water use efficiency. The numerical simulations revealed that the irrigation frequency could be reduced by half during the early growth stage, and the water use efficiency could be greatly improved with the CB layer installed.     

Migration of Sr,Nd and Ce in Unsaturated Chinese Loess under Artificial Sprinkling Conditions: A Field Migration Test

Double concentration peak phenomenon has been observed in nuclide migration tests in unsaturated Chinese loess during the cooperative research between China Institute for Radiation Protection (CIRP) and Japan Energy Atomic Research Institute (JEARI), and was considered conflicting with traditional theory of solute migration. In order to confirm the existence of this phenomenon and better understand its formation mechanism, we conducted a nuclide migration test that lasted 470 days using Sr, Nd and Ce which are analogues of ⁹⁰Sr and actinides, with loess and fine arenaceous quartz, respectively, as tracer carriers. In addition, we examined the efficacy of capillary barrier which is constructed by placing fine-grained soil on a layer of course-grained material, according to its influence on nuclide migration. When using loess as tracer carrier, a fraction of Sr migrated downward from the source layer to form a migration peak, and the residual Sr formed another concentration peak which corresponds to the source layer; while Nd and Ce hardly migrated during the 470 day test with only one concentration peak in the source layer. When using fine arenaceous quartz as tracer carrier, double concentration peak phenomenon occurs for all the nuclides examined, with the peaks distributing, respectively, on the upper and lower sides of the source layer. This phenomenon was suggested to result from the very low water containment ability and nuclide retentivity of the source layer arenaceous quartz. Thus, the so called double concentration peak phenomenon is formed by the source and subsequent migration of part of the source. The obviously reduced migration of Sr when taking fine arenaceous quartz as tracer carrier demonstrated significant influence of the capillary barrier formed by the fine arenaceous quartz layer and overlying loess on nuclide migration. Considering that the fine arenaceous quartz layer is very small (7 mm) in thickness and horizontally placed and the small dimension of the test pit, capillary barrier could be an effective way to protect the underlying waste from leaching.     

渭河咸阳段非饱和层状沉积物中水分分布特征

层状结构是河流相松散沉积物中最常见的沉积结构,通常表现出一些特有的水力学性质,对水分运动过程及沉积物的持水性能产生影响.本文通过对渭河陕西咸阳段河漫滩一个层状沉积物剖面的含水率分布特征进行原位观测,讨论层状沉积物中含水率的分布特征,及其与粒度和毛细壁垒效应的关系.结果表明:在以水平层理和交错层理为主的粗细相间的层状河流沉积物中,天然含水率也呈干润相间的层状分布特征,各层含水率的大小主要与粒度成负相关;沉积物粗细相间的层状分布为毛细壁垒的形成提供条件,在降雨入渗和土壤水蒸发过程中,毛细壁垒效应对水分运动的控制会导致细粒层中含水率高于粗粒层.层状松散沉积物中水分的这种分布规律,为理解土壤持水性能提供了新的思路,对研究土壤含水率与降雨入渗、蒸发等水文过程的关系具有重要意义.     

Zu Eigenschaften,Horizontaufbau und Gliederung der „Haftnässepseudogleye”︁

Properties, horizons and classification of the “Haftnässepseudogleye” (Stagnosols periodically waterlogged with capillary water) The term “Haftnässe” (soil wetness due to capillary moisture) can be used in describing soils with Sg-horizons in which long-term waterlogging and anaerobic conditions occur in the absence of gravitational water. “Haftnässe” is caused by water held in pores with an equivalent diameter of 0.2–50 μm by soil-water tension (pF) between 1.8 and 4.2, when the air capacity of the horizons is very low. “Haftnässe” moves primarily by capillary forces and is available to plants (available water). In some soils, the horizon below the Sg-horizon contains large pores, is well aerated and tends to impede the movement of capillary water. This type of horizon is often wetter than the overlying and underlying horizons, due to the presence of capillary water in the immediately overlying Sg-horizon. The symbol “So” is proposed for such horizons. In these soils, in the Sg-horizon reduced iron compounds are oxidized and precipitated, forming rusty mottles. The sequence of horizons developed in the “Haft(nässepseudo)-gleye” (Stagnosols periodically waterlogged with capillary water) typically affects the continuity of the pathways along which capillary water normally moves. The “Haft(nässepseudo)gleye” are divided into two subtypes on the basis of the sequence of horizons in the soil profile:

• Typical “Haft(nässepseudo)gley” (Shn) exhibits a sequence Ah/Sg/(II)So and shows transitions to Luvisol and Glossisol,
• Thick “Haft(nässepseudo)gley” (Shm) exhibits a sequence Ah/Sg and shows transitions to “Stau(wasserpseudo)gley” (Gleysol periodically waterlogged due to perched water), Gleysol, Fluvisol and tidal marsh soil.

     

再生水灌溉区农田包气带及地下水中硝酸盐分布特征及来源研究

本文通过对华北平原典型再生水灌溉区(河北省石家庄洨河流域)的包气带土壤、地表水和地下水进行采样分析,对硝酸盐在多种环境介质中的来源与环境行为进行了研究,识别了再生水灌溉区地下水硝酸盐污染来源,明确了不同灌溉条件对包气带土壤中硝酸盐迁移的影响。在受到城市再生水严重影响的洨河流域,地下水中的硝酸盐浓度分布范围在4.0 mg·L?1到156.6 mg·L?1之间,已经形成了距离河道2 km、深度70 m的硝酸盐高值区域,经过计算硝酸盐的垂向扩散速率为每年1～2 m。硝酸盐与氯离子的相关性表明,城市再生水是再生水灌溉区包气带、地表水和地下水中硝酸盐的主要来源。利用Geoprobe获取利用不同灌溉水农田土壤剖面样品,研究再生水对厚包气带NO3?-N垂向分布影响,再生水灌溉区和地下水灌溉区中包气带土壤的NO3?-N的平均含量为137.0 mg·kg-1和107.7 mg·kg-1,最高含量523.2 mg·L?1和725.9 mg·L?1,分别出现1.20 m和0.85 m深度,分布规律有着明显的差别。包气带土壤硝酸盐与氯离子的相关性分析表明,再生水灌溉区土壤硝酸盐主要来源于城市再生水,而地下水灌溉区可能来源于农田氮肥。地下水年龄和硝酸盐之间关系表明,地下水中1975年以前补给的硝酸盐浓度低于1975年以后补给,地下水硝酸盐污染与包气带氮入渗的历史过程密切相关。在华北平原特殊的地质水文背景下,农田面源污染对地下水的影响有限,但再生水灌溉区地下水硝酸盐污染的风险较高。     

Modeling finger development and persistence in initially dry porous media

The mechanism for the growth and persistence of gravity-driven fingered flow of water in initially dry porous media is described. A Galerkin finite element solution of the two-dimensional Richards equation with the associated parameter equations for capillary hysteresis in the water retention function is presented. A scheme for upstream weighting of internodal unsaturated hydraulic conductivities is applied to limit smearing of steep wetting fronts. The growth and persistence of a single finger in an initially dry porous media is simulated using this numerical solution scheme. To adequately simulate fingered flow, it was found that the upstream weighting factor had to be negative, meaning that the internodal unsaturated hydraulic conductivities were weighted more by the downstream node. It is shown that the growth and persistence of a finger is sensitive to the character of the porous media water retention functions. For porous media where the water-entry capillary pressure on the main wetting function is less than the air-entry capillary pressure on the main drainage function, a small perturbation will grow into a finger, and during sequential drainage and wetting the finger will persist. In contrast, for porous media where the water-entry capillary pressure on the main wetting function is greater than the air-entry capillary pressure on the main drainage function, the same small perturbation will dissipate by capillary diffusion. The finger widths derived from the numerical simulation are similar to those predicted by analytical theory.     

A review on recent developments in soil water retention theory: interfacial tension and temperature effects

Study of soil physical processes such as water infiltration and redistribution, groundwater recharge, solute transport in the unsaturated zone, compaction and aeration in variably saturated soil hardly is possible without knowledge of the capillary pressure of the soil water as a function of the degree of saturation. Pore space topology, interfacial tension, and temperature probably are the most important physical factors affecting the capillary pressure at a given water content. Despite intensive research in the past decades on the water retention characteristics of soils, our knowledge of their response to varying ambient conditions is far from being complete. Current models of soil water retention as well as of hydraulic conductivity for unsaturated porous media often still use the simplified representation of the pore system as a bundle of cylindrical capillaries. Physical effects, like surface water film adsorption, capillary condensation and surface flow in liquid films, as well as volumetric changes of the pore space are often ignored. Consequently, physical properties of the solid phase surfaces, and their impact on water adsorption and flow, are often not considered. The objective of this contribution is to review various interfacial properties with possible application to the conventional water content — matric potential relation of soils. The ignoring of inter‐facial effects on the water retention of soils is widespread in the literature. The motivation of this paper is therefore to point out some of the more significant deficiencies of our current knowledge on the interaction of solid particle surfaces and the liquid phase in soil. We will first emphasize the impact of the wetting angle on the wetting of dry soil and to present the impact of interfacial tension of the liquid phase in the three‐phase system. At low water content, the transition from capillary‐bound water to adsorbed water and to wetting films is discussed separately, because of its impact on the rewetting process of dry soil. Finally, we discuss the impact of temperature on interfacial tension and water retention of soil as a second important interfacial process affecting directly the water retention of porous media.     

Implication of relationships among suspended sediment size, water discharge and suspended sediment concentration: the Yellow River basin, China

According to the yearly maximum suspended sediment concentrations (SSC) in the Yellow River and its tributaries, the rivers are divided into three types of more than 300, 20–300, and less than 20 kg/m³. The middle Yellow River basin is located in the transitional zone from subhumid to semiarid climates, and covered by a thick loess mantle. Neighboring on the desert areas to the northwest, the surface material of the Loess Plateau exhibits some marked areal differentiation in grain size and forms three zones covered by sandy loess, (typical) loess and clayey loess from northwest to southeast. Controlled by these physico-geographical conditions, the grain size of river-transported sediment shows some particular characteristics; at small water discharge or SSC, the grain size of suspended sediment abruptly decreases to a minimum with increasing water discharge or SSC. At water discharge of more than ca. 40 m³/s or at SSC of more than ca. 40 kg/m³, the grain size increases with water discharge or SSC.During the low-stage season, the relatively clear baseflow may scour the coarse bed materials, so the suspended sediment is relatively coarse. In the rainy season, rainstorm runoff washes out fine loess materials to the river, making suspended sediment fine. During relatively strong rainstorms, there often occur hyperconcentrated flows at SSC of more than 300 kg/m³. The relatively coarse grains could then remain suspended in the mixture of water and fine suspended sediment.     

地表水-地下水交互下傍河土壤硝酸盐氮迁移规律试验研究

为了研究地表水与地下水不同补给关系下硝酸盐氮在傍河农田的迁移规律,选取大沽河河床沙样作为沙槽试验介质,设计地表水与地下水相互补给装置,模拟无补给、地表水补给地下水和地下水补给地表水3种方式下硝酸盐氮在土壤中的迁移,通过测定各取样点硝酸盐氮含量和到达时间,分析了其迁移规律。结果表明:纯淋洗实验中,淋洗强度与沙样颗粒越小,硝酸盐氮在表层沙中的累积越明显,硝酸盐氮的迁移也越慢。地表水与地下水相互补给试验中,补给水位上升,硝酸盐氮的积累量增加、迁移到饱水带的时间缩短;补给水力坡度为0.5时,硝酸盐氮在细沙饱水带中迁移速度约为5.3 cm/min;水力坡度变为0.7时,迁移速度约为9.4 cm/min;补给水力坡度为0.5时,硝酸盐氮在中沙饱水带的迁移速度约为12.3 cm/min。硝酸盐氮在包气带中的积累量随着沙层深度的增加而减少;淋洗强度、水力坡度及沙样颗粒越大,硝酸盐氮在包气带和饱水带中的迁移速度越快;补给水位越高,硝酸盐氮迁移至饱水带的时间越短。     

Factors influencing adoption of soil and water conservation measures in southern Mali

A soil and water conservation (SWC) extension programme, promoting erosion control measures and soil fertility measures, has been going on in southern Mali since 1986. Five factors that influence farmer adoption of SWC measures were analysed: land pressure, cotton‐growing area, possession of ploughing equipment, possession of a donkey cart and farmer training in SWC. Interviews were carried out with 298 farmers and two to three fields per farmer were visited, in 30 representative villages and 30 villages with high SWC adoption. Correlation, regression and factor analysis led to the following conclusions:

• (1) Farmers in the high land‐pressure area adopt more soil fertility measures.
• (2) Farmers in the cotton‐growing area adopt less SWC measures.
• (3) Farmers with more ploughing equipment adopt more SWC measures.
• (4) Farmers with a donkey cart adopt more soil fertility measures.
• (5) Trained farmers adopt more erosion control measures.

There is a strong correlation between the adoption of erosion control measures and soil fertility measures that could not be explained by these five factors only. This suggests that there are additional factors that trigger the adoption of SWC measures. Copyright © 2003 John Wiley & Sons, Ltd.     

Water retention of light expanded clay amendment

Abstract

Shallow‐drained horticultural soils utilized in containers, sporting areas, and landscape sites tend to retain excess water and thereby be poorly aerated as a consequence of capillary retention following irrigation or precipitation. This problem is usually corrected by soil physical amendment with coarse‐textured particulates to add large pores which drain and provide adequate aeration. A variety of materials are used for soil physical amendment. This study examined the water retention of one of the newer amendments used for this purpose, light expanded clay amendment (LECA), relative to its use in shallow‐drained soils. Although LECA is a porous material, its contribution to soil physical properties when used as an amendment were found to be similar to non‐porous amendments such as river sand or gravel because the internal water is not readily available for plant use.     

Evaluation of pumice as a perlite substitute for container soil physical amendment

Abstract

Shallow‐drained horticultural soils utilized in containers, sporting areas, and landscape sites tend to retain excess water and be poorly aerated as a consequence of capillary retention following irrigation or precipitation. This problem is usually corrected by soil physical amendment with coarse‐textured particulates which add pores sufficiently large to drain and provide adequate aeration. A variety of materials are used for soil physical amendment. One of the most common and successful amendments is perlite. This study examined the feasibility of using pumice, a very similar mineral, as a substitute for perlite in soil amendment.

The physiochemical properties of pumice important to its use as a container soil amendment were found similar to those of perlite.     

Development of an apparatus for measuring one‐dimensional steady‐state heat flux of soil under reduced air pressure

One of the best ways to evaluate the coupled heat and mass transfer in soil is to measure the heat flux and water distribution simultaneously. For this purpose, we developed an apparatus for measuring the one‐dimensional steady‐state heat flux and water distribution in unsaturated soil under reduced air pressure. The system was tested using four samples with known thermal conductivity (0.6–8.0 W m^?1 K^?1). We confirmed that the system could measure the one‐dimensional steady‐state heat flux under a fixed temperature difference between ends of the samples over a wide range of thermal conductivity values. Time domain reflectometry was used to measure the water distribution with a repeatability of less than ± 1.0%. We used the apparatus to measure the soil heat flux and distribution of water content and temperature under steady‐state conditions with reduced air pressure. The initial volumetric water content, θ_ini, of the soil samples was set at 0.20 and 0.40 m³m^?3. For a θ_ini of 0.20, the heat flux was not significantly affected by air pressure, and the water content on the hot side decreased whilst that on the cold side increased, i.e. a pronounced water content gradient was formed. For a θ_ini of 0.40, the heat flux increased sharply with reduced air pressure, and the water content did not change, i.e. a homogeneous water distribution was observed. The increase in the heat flux with air pressure reduction is caused by the vapour transfer in soil pores. We found that a large vapour transfer took place in the soil with the homogeneous water distribution, and that the vapour transfer was less in the soil with the pronounced water content gradient. These experimental facts were entirely different from the traditional knowledge of vapour transfer in soil under temperature gradients. A lack of data on heat flux must have resulted in the previously incorrect conclusions. The new apparatus will serve to clarify the intricate phenomena of thermally induced vapour transfer in unsaturated soil in further experiments.     

恒温下相对湿度对果蔬热风干燥特性和品质的影响及调控

相对湿度作为干燥介质的重要参数，对干燥热质传质过程和干燥品质具有显著影响。但由于相对湿度对干燥过程的影响机理及优化调控机制尚不明确，导致相对湿度的调控方式多依靠经验，造成干燥效率低、品质差、能耗高等问题。对于传质过程，降低相对湿度能够增大对流传质系数，加快物料表面水分蒸发；而对于传热过程，升高相对湿度能够增大对流传热系数，加快物料升温速率。相对湿度较高时，物料升温速率快，内部水分迁移量增大，但表面水分蒸发量较小；而当相对湿度较低时，物料升温速率较慢，内部水分迁移量较小，但表面水分蒸发量较大。相对传热和传质过程的影响此消彼长，互相耦合。高相对湿度主要体现为对传热过程的影响，低相对湿度主要体现为对传质过程的影响。高相对湿度能够抑制物料表面的结壳，并能够提高复水性，降低收缩率。阶段降湿及多阶段降湿干燥方式下物料表面形成和保持了蜂窝状多孔结构，能够提高干燥效率和品质。基于监测物料温度的相对湿度调控方式被验证为较忧的相对湿度控制方式。阶段降湿干燥方式适用性的实质为：干燥过程中所体现出的对流传热热阻和内部导热热阻的相对大小，及对流传质阻力和内部传质阻力的相对大小，不同干燥条件和物料种类、厚度会影响以上传热传质阻力的大小，从而呈现出不同适应性的结果。当阶段降湿干燥过程中传热毕渥数>1且传热毕渥数>0.1时，说明阶段降湿干燥过程适用于此物料的干燥。该文综合论述了相对湿度对果蔬热风干燥过程中热质传递及干燥品质的影响，优化调控策略及适用性范围4个方面内容，明确了果蔬热风干燥过程中相对湿度的影响机理，为相对湿度的优化调控提供理论依据和技术支持。     

Water repellency of volcanic ash soils from Ecuadorian páramo: effect of water content and characteristics of hydrophobic organic matter

Water repellency of volcanic ash soils from the Ecuadorian páramo was studied by a combination of extraction and analysis of water‐repellent products, Molarity Ethanol Droplet values, water contact‐angle measurements by capillary rise, and N₂ adsorption isotherms. The undried samples studied are hydrophilic, but exhibit water repellency after moderate drying (48 hours at 30°C). The advancing water contact‐angle measured by capillary rise varies from 78° to 89°. These water contact‐angles decrease strongly after extraction of organic materials by an isopropanol–water mixture. Elemental analysis, infrared spectra and gas chromatography‐mass spectrometry analyses were used to characterize the extracts. The results show that long‐chain fatty acids and more complex non‐polar alkyl components (waxes) are the main water‐repellent materials. The deposition of such extracted materials onto hydrophilic sand leads to the rapid increase of water contact‐angle until values close to those measured on the soil samples are achieved. Assuming a coating of the mineral surface by organic hydrophobic products and using Cassie's law, the water contact‐angle of extracted materials was computed. The values ranged from 100° to 157°. Nitrogen specific surface areas of the soils studied were very small, indicating a low adsorbent–adsorbate interaction on hydrophobic surfaces. These results partially validate the hypothesis of water‐repellent materials that occur as coatings at least after a drying process.     

固体废物处理厂地下水污染预测及控制模拟

[目的]以江苏省镇江市新区大港片区某固体废物处理厂为研究对象,对地下水污染情况进行模拟研究,为同类建设项目及企业的地下水污染预测和防治提供参考。[方法]通过系统分析该固体废物处理厂野外水位和水质观测数据以及水文地质条件等资料,利用Visual Modflow软件构建了地下水水流和溶质运移模型。[结果]对厂区污水处理站防渗破损后特征污染物CODMn和氨氮运移情况以及地表硬化污染控制措施对污染物的阻隔效果进行预测评价,数值模拟预测污染物的影响范围、超标范围和最大运移距离。预测时间20a后,污染物影响范围最大,运移距离最远,且CODMn影响范围较氨氮大,运移距离较远;地表硬化后,20a后污染羽未超出评价范围。[结论]污染物主要沿水流方向迁移,对水环境的影响随时间逐渐增大,污染物浓度随着迁移距离的增加而减小,不同污染物在地下水含水层中的溶质运移范围和迁移距离不同。地表硬化措施能有效控制污染物扩散。     

The effect of micro-heterogeneity and capillary number on capillary pressure and relative permeability curves of soils

The determination of the two-phase flow coefficients (such as the capillary pressure, P_c, and relative permeabilities, k_rw, k_ro) is of a key importance to model the two-phase flow processes taking place during contaminant transport in subsurface. In the present work, transient immiscible displacement experiments are performed at various flow rates on long disturbed soil columns. The capillary pressure-saturation-relative permeability relationships of soils characterized by narrow and broad grain size distributions are estimated with inverse modeling from rate-controlled displacement experiments and are correlated with the grain size variability and ratio of viscous to capillary forces (capillary number). A soil core holder assembled with electrodes is constructed to monitor the axial distribution of water saturation. A new technique is developed to determine the water saturation averaged over successive segments of the soil column by measuring the transient responses of the electrical resistance between vertical ring electrodes. The transient responses of the average oil (water) saturation in five segments along with the total pressure drop across the soil column are introduced into an inverse modeling numerical solver of the macroscopic two-phase flow equations to estimate simultaneously the capillary pressure and relative permeability curves under dynamic conditions. The water and oil relative permeabilities increase drastically with the capillary number, while the capillary pressure curve of soils with broad grain (pore) size distribution is wider than that of soils with narrow grain (pore) size distribution. For soils with high variability of grain sizes, the irreducible wetting phase saturation is higher, the relative permeability curves are sharper and the end oil relative permeability is higher compared to soils with low variability of grain sizes.     

Water retention characteristics of coarse porous materials to construct purpose-designed plant growing media

ABSTRACT

Among potential components to construct Technosols for urban greening purposes, the commercially available geogenic coarse porous materials (CPMs) are mainly used in practice because of their high porosity. However, the knowledge of the hydraulic behavior of CPMs as well as of their mixtures with other substrates is limited, provoking their suboptimal usage. Therefore, we determined the water retention characteristics, including the available water capacity (AWC) of six geogenic CPMs: porlith, expanded shale, expanded clay, tuff, pumice, and lava. In order to obtain the water retention characteristics of the CPMs as well as of their mixture with sand (1:4 per volume), the following methods adapted from soil physics were applied over a wide range of pressure heads: Equi-pF apparatus, ceramic tension plates, pressure plate extractors, WP4C apparatus, and water vapor adsorption. The results were used to parametrize the modified Kosugi model (using SHYPFIT 2.0). Porlith and tuff have the highest AWC (0.37 m³ m^?3 and 0.17 m³ m^?3, respectively) and are the only ones which can be recommended as effective water-retaining materials. Further materials exhibit an AWC less than 0.10 m³ m^?3. The CPMs exhibit a bimodal pore size distribution, which can be well described by the applied model, except for pumice and expanded shale. The mixtures present overall low AWCs up to 0.07 m³ m^?3, with the pure sand having less than 0.03 m³ m^?3. For practical application a quite high ratio of CPM is needed, and the mixing material must be adapted to the hydraulic properties of the CPMs. The water inside the CPMs may be easily available for plant roots able to penetrate in the CPMs’ coarse pores.