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Soil temperature of vegetated landfill earthen covers varies with time during their service, due to heat released by the degradation of municipal solid waste. In this study, an experimental campaign to capture soil water-retention curve (SWRC) and hydraulic conductivity function (HCF) of unsaturated rooted soils was conducted at different temperatures (25, 45, and 60 [degrees]C). Simplified evaporation tests were conducted by subjecting soil specimens to a prolonged drying period at maintained temperature. Based on the responses of matric suction and water content, SWRC and HCF were determined by the instantaneous profile method. It was found that increasing temperature reduced water-retention capacity, due to root shrinkage, thermal expansion of liquid phase, and reduction in forces of capillarity and adsorption. Soil hydraulic conductivity was enhanced by the increase in soil temperature due to reduction of water viscosity and potential preferential flow at root channels induced by root shrinkage. Temperature effects on SWRC and HCF of rooted soils are suction-dependent. A new nonisothermal SWRC model was developed to capture the dual effects of roots and temperature. By using the same set of calibrated parameters, the model demonstrates its ability to predict SWRCs reasonably well within the range of temperature investigated. Key words: unsaturated soils, vegetation, temperature effects, soil water retention curve, hydraulic conductivity, 1. Introduction Landfilling is one of the most prevailing ways of waste treatment nowadays because of high feasibility, financially affordable cost, and relatively low environment risk. After waste layer being [...]

Context. Soil thermal properties influence soil health parameters and can help determine crop productivity with changing global atmospheric climate. Aim. This study investigated the influence of no-till (NT) and cover crop (CC) management on soil thermal properties. Methods. The study site was managed with NT. The CCs used included hairy vetch (Vicia villosa Roth.), crimson clover (Trifolium incarnatum L.), winter wheat (Triticum aestivum L.), winter peas (Lathyrus hirsutus L.), oats (Avena sativa), triticale (Triticale hexaploide Lart.), barley (Hordeum vulgare L.) and flax (Linum usitatissimum L.). Soil samples were collected at 010, 10-20, and 2030 cm depths just prior to CCs being planted and also collected just before CCs were terminated. Treatments included NT CC and NT no cover crop (NC). Soil thermal properties (thermal conductivity [A], volumetric heat capacity [[C.sub.V]], and thermal diffusivity [D]) were measured at 0, -33, and -100 kPa soil water pressures. Key Results. [C.sub.V] at saturation was 13% higher under CC management compared with NC management. Averaged over all depths just before CC termination, A and D at saturation were 21 and 35% higher, respectively, under NC management compared with CC management probably due to closer contact between soil particles. Conclusions. Results from this study suggest CCs with NT management may be able to resist extreme soil temperature changes which could improve soil health and crop productivity in these systems. Implications. NT and CC could improve crop productivity in the future but more in situ studies of soil thermal properties under these systems are needed. Keywords: bulk density, cover crops, no-till, soil organic carbon, thermal conductivity, thermal diffusivity, volumetric heat capacity, volumetric water content., Introduction Soil health and crop productivity are directly related to and influenced by various land management practices such as mechanical soil manipulation and crop rotation, among others. Tillage has been [...]

Commercial nitrification inhibitors (NIs), namely nitrapyrin, 3,4-dimethylpyrazol phosphate (DMPP) and dicyandiamide (DCD), are ineffective at high temperatures. Therefore, it is imperative to explore new compounds that can be commercialised as effective NIs for warm climatic conditions. The aim of the present study was to compare the potential of 4-amino-1,2,4-triazole (ATC) with the two commercial NIs DMPP and DCD to delay nitrification of [(N[H.sub.4]).sub.2]S[O.sub.4] in an alkaline calcareous soil incubated under aerobic conditions at warm temperatures (35 and 25[degrees]C). Inhibitors were incorporated in [(N[H.sub.4]).sub.2]S[O.sub.4] granules and nitrification inhibition was calculated on the basis of net N[H.sub.4.sup.+]-N disappearance and net N[O.sub.3.sup.-] -N accumulation. At 35[degrees]C, the inhibitory effect of DCD and DMPP persisted only for 1 week, whereas ATC was effective up to 4 weeks. At 25[degrees]C, the inhibitory effect of ATC, DMPP and DCD was comparable. In another set of experiments, different concentrations of ATC (0.25-6% of N) were tested at three different temperatures (35, 25 and 18[degrees]C). At 35[degrees]C, ATC applied at 2% of N caused 63% inhibition for 2 weeks, whereas at a rate of 4-6% of N the inhibitory effect of ATC persisted up to 4 weeks (63-84% inhibition). At 25[degrees]C, ATC application at a rate of 1% of N caused 64% inhibition for 2 weeks; increasing the application rate to 2-6% of N prolonged the inhibitory effect up to 4 weeks (55-94% inhibition). At 18[degrees]C, a much lower concentration of ATC (0.25-0.5% of N) was required to achieve [greater than or equal to] 50% inhibition for 2-4 weeks, whereas increasing the application rate to 2% of N caused 93% inhibition for 4 weeks. The results of the present study suggest that although commercially available NIs are ineffective at high summer temperatures, ATC may have the potential to be commercialised as an effective N1 for warm as well as moderate climatic conditions. Additional keywords: nitrogen fertilisers, subtropical soils., Introduction Among major nutrients required for crop production, fertiliser N has the most important role regarding economic benefits and environmental impacts. However, fertiliser N is not being used efficiently, because [...]

Rain-harvesting planting can improve crop biomass and enhance precipitation use efficiency in rainfed semiarid areas. In this study, field trials were conducted during summer 2007-2010 to determine the impacts of different mulching patterns in rainfall harvesting planting on spring com growth and development in a typical semihumid dryland farming area of the Loess Plateau in China, which is characterised by spring droughts. Rain-harvesting ridges and planting furrows were mulched with 8% biodegradable film ([RC.sub.SB]), liquid film ([RC.sub.SL]), or not mulched ([RC.sub.SN]), and bare land drilling without mulching served as the control (CF). We found that the rain-harvesting effects of ridges and the evaporation-inhibiting and moisture-conserving effects of mulching materials during the spring com growing season significantly increased water storage in the 0-100 cm soil layer (P 0.05) of the treatments on water storage. During 2007-2010, the average plant height increased by 26.6%, 15.4%, and 11.1% under [RC.sub.SB], [RC.sub.SL], and [RC.sub.SN] relative to CF respectively, whereas the per plant biomass increased by 26.6%, 15.4%, and 11.1% under these treatments, and the grain yield increased by 32.3%, 17.5%, and 15.0%. Therefore, in the semihumid dryland fanning areas of the Loess Plateau, rain-harvesting planting greatly increased the growth, development, and dry matter accumulation by spring com, thereby enhancing its biomass yield, whereas the plastic-covered ridges and furrows mulched with biodegradable films substantially increased the yield-enhancing effects. Additional keywords: furrow mulching, Loess Plateau of China, rain-harvesting planting, soil temperature, soil water storage, yield., Introduction The semihumid dryland farming areas of China have a vitally important role in the development of arid agriculture (Yao and Yin 1999). In these areas, particularly in recent years, [...]

Numerous models have been developed to predict the thermal conductivity of soils at a range of different densities and moisture contents. This paper evaluates four thermal conductivity models, developed by various researchers, by comparing their performance against experimental results obtained on 27 different soils prepared at a range of saturation levels and densities. The results demonstrate that, in general, all four models show good agreement between experimental thermal conductivity and modelled thermal conductivity. The only significant shortfall is observed in low-saturated sands when using two of the models. A detailed analysis of the empirical soil parameters used in three of the recent models is presented. It shows that the accuracy of the three models can be improved by modifying the empirical soil parameters to fit the experimental data. Key words: soils, thermal conductivity, thermal conductivity models, heat transfer. De nombreux modeles ont ete developpes afin de pouvoir predire la conductivite thermique des sols de densites et teneurs en eau variees. Dans le present article, on evalue quatre modeles de conductivite thermique, elabores par differents chercheurs, en comparant leur performance d'apres les resultats obtenus avec 27 sols prepares presentant des niveaux de saturation et des densites differents. Les resultats montrent, en general, que dans les quatre modeles il y a une bonne concordance entre la conductivite thermique experimentale et la conductivite thermique modelisee. La seule lacune importante est observee dans le cas des sables faiblement satures lorsqu'on utilise deux de ces modeles. On presente ici une analyse approfondie des parametres du sol empiriques utilises dans trois des recents modeles. Celle-ci montre qu'il est possible d'ameliorer la precision des trois modeles en modifiant les parametres du sol empiriques afin qu'elles concordent avec les donnees experimentales. [Traduit par la Redaction] Mots-cles: sols, conductivite thermique, modeles de conductivite thermique, transfert de chaleur., Introduction Density, moisture content, mineralogy, texture, and temperature can all influence the thermal conductivity of a soil. Not surprisingly, with so many variables controlling the thermal conductivity, many theories and [...]

European beech (Fagus sylvatica L.) is an economically and ecologically important forest tree species in Europe. Expected future temperature increases due to global climate change may significantly affect growth of beech trees and consequently influence carbon cycling in beech forests. We tested the hypothesis that soil temperature influences the growth of both belowground and aboveground parts of beech seedlings. One-year-old seedlings were transferred into rhizotrons and subjected to two different soil temperatures for 2 years while the soil moisture level was kept constant. The main effect of the soil temperature was a changed biomass of the woody part of the seedlings. Soil temperature significantly influenced the biomass of shoots and roots and diameter of the stem, which were the highest for the seedlings grown in conditions of soil temperatures maintained in the range of summer soil temperatures from the site of origin of the seedlings. Increased soil temperature also resulted in increased specific root length and specific root tip density. Root-to-shoot ratio and leaf parameters (leaf mass, number of leaves, and specific leaf area), except for leaf area ratio, were not influenced by soil temperature. Key words: Fagus sylvatica, biomass allocation, fine roots, rhizotrons, cooling of the root system, soil warming, specific root length. Le hetre commun (Fagus sylvatica L.) est une essence forestiere ecologiquement et economiquement importante en Europe. L'augmentation anticipee de la temperature due aux changements climatiques globaux peut avoir un effet nefaste significatif sur la croissance des hetres et par consequent sur le recyclage du carbone dans les hetraies. Nous avons teste l'hypothese voulant que la temperature du sol influence la croissance des parties souterraine et aerienne des semis de hetre. Des semis d'un an ont ete transferes dans des rhizotrons et soumis a deux temperatures du sol differentes pendant deux ans en gardant le meme degre d'humidite du sol. Le principal effet de la temperature du sol a ete le changement dans la biomasse des tissus ligneux des semis. La temperature du sol a eu une influence significative sur la biomasse des pousses et des racines et sur le diametre de la tige dont les valeurs etaient les plus elevees chez les semis cultives dans un sol dont la temperature etait maintenue dans la gamme de temperatures estivales observees dans le sol des sites d'oU provenaient les semis. L'augmentation de la temperature a aussi augmente la longueur racinaire specifique et le nombre d'apex racinaires par unite de poids. Le rapport racines-pousses et les parametres foliaires (masse foliaire, nombre de feuilles, et surface foliaire specifique) a l'exception de l'indice de surface foliaire, n'ont pas ete influences par la temperature du sol. [Traduit par la Redaction] Mots-cles : Fagus sylvatica, allocation de biomasse, racines fines, rhizotrons, refroidissement du systeme racinaire, rechauffement du sol, longueur racinaire specifique., Introduction Currently, European beech (Fagus sylvatica L.) is a widely spread tree species in central and western Europe. In the northern part of its range, it prefers low altitudes, whereas [...]

Large-scale evaporation experiments were conducted on bare sand using an environmental chamber. Four different atmospheric conditions and various drying durations were imposed on the soil sample. Atmospheric parameters (air flow rate, relative humidity, and temperature) and response of the soil (volumetric water content, temperature, and soil suction) were both monitored simultaneously. Notably, the temperature and matric suction at the soil surface were monitored using an infrared thermometer and high-capacity tensiometer, respectively. The results show that the air and soil temperatures depend on the evaporation process and atmospheric conditions. In addition, volumetric water content in the near-surface zone is strongly affected by the evaporation process and changes linearly over depth. The evaporation rate is strongly dependent on the air conditions. Key words: soil water evaporation, environmental chamber, Fontainebleau sand, soil surface suction. Des experiences d'evaporation a grande echelle ont ete realisees sur du sable nu a l'aide d'une chambre environnementale. Quatre conditions atmospheriques differentes et des durees de sechage variees ont ete imposees a l'echantillon de sol. Les parametres atmospheriques (debit d'air, humidite relative et temperature) et les reponses du sol (teneur en eau volumique, temperature et succion du sol) ont ete mesures simultanement. Par exemple, la temperature et la succion matricielle a la surface du sol ont ete mesurees respectivement a l'aide d'un thermometre a infrarouge et d'un tensiometre a haute capacite. Les resultats demontrent que les temperatures de l'air et du sol dependent du processus d'evaporation et des conditions atmospheriques. De plus, la teneur en eau volumique dans la zone pres de la surface est fortement affectee par le processus d'evaporation et varie lineairement en fonction de la profondeur. Le taux d'evaporation est tres dependant des conditions de l'air. [Traduit par la Redaction] Mots-cles: evaporation de l'eau du sol, chambre environnementale, sable de Fontainebleau, succion a la surface du sol., Introduction Soil water evaporation at the air-soil interface is an important water cycle and energy exchange process, which causes many problems in various fields: soil degradation in arid areas with [...]

The temperate rainforest on the Olympic Peninsula represents a biome that is characterized by unusually high epiphyte biomass and accompanying canopy soils. These canopy communities form thick mats that play important ecological roles: increasing ecosystem nutrient capital, fostering abundant invertebrates, and enhancing moisture retention. Little is known about the physical properties and microenvironmental conditions of these mats. We investigated seasonal patterns in temperature and moisture of canopy soils and compared them to O- and A-horizon terrestrial soils. Temperature tended to fluctuate more in canopy soils than in terrestrial soils. During the 4 months of highest precipitation, canopy soils also showed higher maximum saturation levels than terrestrial soils. Both soil types displayed sharp 'dry-downs' during the summer dry season, which contrasts with results from similar research in a tropical cloud forest, where only canopy soils dried significantly during the dry season. In the late summer in the Olympic Rainforest, canopy soils remained dry until the first rainfall, whereas terrestrial soils began to rehydrate a month earlier, possibly through hydraulic redistribution. Regional climate models predict increased winter precipitation but drier summers for this area. Our results suggest that extended summer droughts may increase canopy drying, which may have negative impacts on epiphyte communities. Key words: temperate rainforest, arboreal soil, epiphyte mats, canopy. Resume : La foret temperee ombrophile de la Peninsule Olympic represente un biome caracterise par une biomasse epiphyte particulierement abondante, accompagnee de sols de canopee. Ces communautes de la canopee forment des coussins epais jouant des roles ecologiques importants : augmentation de la reserve en nutriments de l'ecosysteme, encouragement d'une abondante proliferation d'invertebres, augmentation de la retention de l'humidite. On connait peu de chose au sujet des proprietes physiques et des conditions micro environnementales de ces coussins. Les auteurs ont examine les patrons saisonniers de la temperature et de l'humidite des sols de canopee avec celles des horizons O et A des sols terrestres. La temperature a tendance a fluctuer plus fortement dans les sols de canopee que dans les sols terrestres. Au cours des 4 mois les plus pluvieux, les sols de canopee montrent egalement un maximum de saturation plus eleve que les sols terrestres. Les deux types de sol montrent une nette dessiccation au cours de la saison seche estivale, ce qui contraste avec les resultats de recherches similaires conduites dans la foret tropicale ombrophile, ou seuls les sols de canopee sechent significativement au cours de la saison seche. A la fin de l'ete, dans la Peninsule Olympic, les sols de canopee demeurent secs jusqu'a la premiere pluie, alors que les sols terrestres commencent a se rehydrater un mois plus tot, possiblement par redistribution hydraulique. Les modeles climatiques regionaux predisent une augmentation des precipitations hivernales, mais des etes plus secs pour cette region. Les resultats suggerent que la prolongation de la duree des secheresses estivales pourrait augmenter la dessiccation de la canopee, ce qui pourrait avoir des impacts negatifs sur la communaute epiphyte. [Traduit par la Redaction] Mots-cles: foret ombrophile temperee, sol arboricole, coussins d'epiphytes, canopee., Introduction Old-growth temperate forests of the western slopes of the Olympic Mountains host extremely high epiphyte biomass and diversity (Franklin and Dyrness 1988; Kirk and Franklin 1992), supporting communities that [...]

A model has been developed for the daily variation in soil temperature at 5 cm depth, for use where both the minimum and maximum temperatures are known or can be estimated. The model is based on data from three Australian sites with minute-by-minute data over 3-7 years. The model uses two sine curves; one for the increase from minimum to maximum and another for the relatively rapid decrease in temperature immediately after the maximum. An exponential decay function is used for the slower decrease in temperature until the minimum is reached. The time of the minimum soil temperature is primarily determined by the time of sunrise and therefore varies depending on the day of the year, whereas the time of the maximum temperature is influenced primarily by the time of the middle of the day (midpoint between sunrise and sunset). The time of the transition point between the maximum and the next minimum is related to the time of sunset. Therefore, the model uses latitude, longitude, and the day of the year to determine the time of sunrise and sunset to adjust the shape of the temperature profile throughout the day. The model has been validated using 3-hourly soil temperature data for 35 other sites in Australia, with a correlation of 0.993 between actual 3-hourly temperatures and those predicted. Its use for degree-day calculations has been validated using hourly data from a site in Victoria, where the model's estimates of degree-days differ Additional keywords: daily temperature profile, air temperature., Introduction The development of plants (He et al. 2010), insects (Dallwitz 1984), and soil microbes (Uchida et al. 2010) is temperature-dependent and is often calculated using degree-days or similar units [...]

Land surface and subsurface variables, such as soil moisture-suction and temperature, are among the most important components to study the behaviour of expansive soil, geothermal energy, and climate change. A more accurate and long-term series of soil moisture and temperature prediction, due to ground-atmosphere interaction, is very important for real-time drought monitoring for understanding and improving the behaviour of soil, buried structures, and climate prediction. In this study, ground-atmosphere interaction is numerically modelled using Vadose/W software for two instrumented sites in Melbourne, Australia. Soil moisture and temperature down to 2 m depth were monitored over 2 years at discrete locations and the meteorological variables including air temperature, air humidity, wind speed, precipitation, and solar radiation were measured from a weather station installed at the sites. Further, laboratory and field tests were performed to establish initial conditions and soil characteristics such as the soil-water characteristic curve (SWCC), hydraulic conductivity, and thermal conductivity functions. The numerical model results were calibrated with the field data, indicating good agreement between numerical and field results. The calibrated numerical model was used to compute the long-term moisture and temperature variations into the immediate future using the past 20 years of weather data in Melbourne. Key words: climate model, expansive soil, soil moisture content, soil temperature, meteorological conditions. Les variables de la surface du sol et celles sous la surface, telles que la succion, la teneur en eau et la temperature du sol, font partie des composantes les plus importantes dans l'etude du comportement expansif d'un sol, de l'energie geothermique et des changements climatiques. Une serie de donnees plus precise et plus longue sur la prediction de la teneur en eau d'un sol et de la temperature, basee sur l'interaction sol-atmosphere, est tres importante pour le suivi en temps reel de secheresses, et pour la comprehension et l'amelioration du comportement du sol, des structures enfouies et la prediction du climat. Dans cette etude, l'interaction sol-atmosphere est modelisee numeriquement avec le logiciel Vadose/W a partir de deux sites instrumentes a Melbourne, Australie. La teneur en eau et la temperature du sol a ete suivie pendant plus de 2 ans sur des positions ponctuelles jusqu'a 2 m de profondeur, et les variables meteorologiques incluant la temperature de l'air, l'humidite de l'air, la vitesse des vents, les precipitations et la radiation solaire ont ete mesurees a l'aide d'une station meteo installee sur les sites. De plus, des essais de laboratoire et de terrain ont ete realises afin d'etablir les conditions initiales et les caracteristiques du sol comme la courbe de retention d'eau (CRE), la conductivite hydraulique et les fonctions de conductivite thermique. Les resultats du modele numerique ont ete calibres avec les resultats de terrain, ce qui a demontre une bonne correlation entre les resultats numeriques et de terrain. Le modele numerique calibre a ete utilise pour calculer les variations a long terme de la teneur en eau et les variations dans un futur immediat de la temperature a partir des donnees meteorologiques des derniers 20 ans a Melbourne. Mots-cles : modele climatique, sol expansif, teneur en eau du sol, temperature du sol, conditions meteorologiques. [Traduit par la Redaction], Introduction The behaviour of expansive soil is primarily related to soil moisture-suction variation within the soil profile due to ground-atmosphere interaction. In general, soils close to the ground surface are [...]

Relations between snow cover, active-layer thickness, and near-surface ground temperatures were determined in 2005-2009 for a diverse range of alluvial and upland settings in the outer Mackenzie Delta. Here, the snow cover developed primarily by wind redistribution, with its spatial variation controlled by topography in uplands and vegetation height in alluvial lowlands. Snow cover was the primary influence on freeze-back duration and the mean annual temperature at the top of permafrost (TTOP), with the difference in median TTOP between alluvial (-3.7°C) and upland (-6.1°C) settings related to the greater snow depth and soil moisture in the alluvial plain. The active layer was generally deeper in the wet alluvial lowlands, where the average duration of active-layer freeze back (101 days) was nearly double the time taken in the well-drained uplands (55 days). The surface offset ([increment of [T.sub.S]]; up to 11°C) dominated the difference between annual mean air temperature (AMAT) and TTOP ([increment of T]). In alluvial terrain, [increment of [T.sub.S]] varied with snow depth, but in the uplands, [increment of [T.sub.S]] was more consistent from site to site. The small thermal offset ( Les relations entre la couverture de neige, l'epaisseur de la couche active et les temperatures du sol pres de la surface ont ete determinees entre 2005 et 2009 pour divers environnements alluviaux et de hautes terres des abords du delta du Mackenzie. La, la couverture de neige se developpe principalement par redistribution par le vent, la variation spatiale etant controlee par la topographie des hautes terres et la hauteur de la vegetation dans les basses terres alluviales. La couverture de neige influait le plus la duree du regel et la temperature moyenne annuelle au sommet du pergelisol; la difference de la mediane de la temperature au sommet du pergelisol entre les environnements alluviaux (-3,7°C) et ceux des hautes terres (-6,1°C) etait reliee a la plus grande profondeur de neige et l'humidite du sol dans la plaine alluviale. La couche active etait generalement plus profonde dans les basses terres alluviales humides, ou la duree moyenne du regel de la couche active (101 jours) etait pres du double de celle dans les hautes terres bien drainees (55 jours). Le decalage a la surface ([increment of [T.sub.S]]; pouvant atteindre 11°C) dominait la difference entre la temperature moyenne de l'air et celle au sommet du pergelisol ([increment of [T.sub.S]]). Dans les terrains alluviaux, [increment of [T.sub.S]] variait selon la profondeur de la neige mais, dans les hautes terres, la valeur de [increment of [T.sub.S]] demeurait plus constante entre les sites. Le petit decalage thermique ( [Traduit par la Redaction], Introduction Variations in surficial geology and geomorphology between alluvial and glacigenic deposits in the outer Mackenzie Delta give rise to a suite of distinct biophysical environments (Mackay 1963; Burn and [...]

Two types of freezing tests have been conducted on Xuzhou silty clay. The intermittent freezing test results show that the frost heave increases step by step after the initial freezing stage, and its total amount is only 48.8% that resulting from the continuous freezing test. A model describing the growth process of the active ice lens in saturated, rigid soils has been established, and the importance of the frozen fringe is investigated in the model. The growth processes of the final ice lenses in the two freezing tests have been used for laboratory validation of the model, and the calculated results are in general agreement with the experimental data. The mechanism of using an intermittent freezing mode to reduce frost heave has been revealed by analyzing the growth process of the final ice lens. We indicate that, during the noncooling stage, the backward movement of the freezing front, which causes the disappearance of the frozen fringe, stops the growth of the final ice lens. This effect results in a step-type frost heave curve in the intermittent freezing test and reduces the heave amount effectively. Finally, problems concerning the practical application of the intermittent freezing mode are discussed in a preliminary manner. Key words: frost heave, artificial ground freezing technique, final ice lens, intermittent freezing mode, mathematical model. Deux types d'essais de gel ont ete realises sur de l'argile silteuse de Xuzhou. Les resultats demontrent que le soulevement par le gel lors d'un essai de gel intermittent augmente etape par etape apres le gel initial, et que le total est seulement 48,8 % du soulevement obtenu lors d'un essai de gel continu. Un modele decrivant le processus de croissance de la lentille de glace active dans les sols satures et rigides a ete etabli, et l'importance de la frange gelee du sol est evaluee a l' aide de ce modele. Le processus de croissance de la lentille de glace finale des deux essais de gel a ete utilise pour la validation au laboratoire du modele. Les resultats calcules correspondent generalement bien avec les donnees experimentales. Le mecanisme qui permet de reduire le soulevement par le gel par l'utilisation du mode de gel intermittent a ete revele par l'analyse du processus de croissance de la lentille de glace finale. Il a ete demontre que durant l'etape sans refroidissement, le mouvement de recul du front de gel, qui entraine la disparition de la frange gelee, arrete la croissance de la lentille de glace finale. Cet effet produit une courbe de soulevement par le gel de type par etapes lors d'essais de gel intermittent et reduit effectivement le soulevement. Finalement, des problemes concernant l'application pratique du mode de gel intermittent sont discutes de facon preliminaire. Mots-cles : soulevement par le gel, technique de gel artificiel du sol, lentille de glace finale, mode de gel intermittent, modele mathematique. [Traduit par la Redaction], Introduction Geotechnical engineering projects comprising shafts, tunnels, subways, and deep foundations often encounter great difficulties from aquiferous, weak, and low-strength strata. Several decades of experience indicates that the artificial ground [...]

Precipitation is the major factor limiting crop growth in the semi-arid Loess Plateau region of China. Ridgeand-furrow rainfall harvesting systems (RFRHS) with mulches are used to increase water availability to crops, thereby improving and stabilising agricultural production in the semi-arid region of China. We conducted a field experiment from 2007 to 2010 in the Weibei Highlands of China, to determine the influence of RFRHS with different mulching patterns on soil water content, temperature, water-use efficiency, and maize yield (Zea mays L.). Ridges were covered with standard plastic film in all RFRHS treatments, while different furrow treatments were mulched with standard plastic film (PP), biodegradable film (PB), maize straw (PS), or liquid film (PL), or left uncovered (P). A conventional flat treatment without mulching was used as the control. In the early stage of maize growth, the topsoil temperature (5-20 cm) under PP and PB was significantly (P Additional keywords: mulch, ridge and furrow rainwater harvesting, spring maize, soil temperature, soil water, yield., Introduction The Weibei Highlands, in the southern Loess Plateau of China, is a semi-humid agricultural area that is liable to drought. Precipitation is the major water resource used for agricultural [...]

Temperatures were measured along instrumented geogrids to determine thermal strains and their changes with seasonal temperatures. It was observed that the application of temperature correction to the measured strain values by electrical wire resistance (EWR) strain gauges to compensate for temperature-induced strains is not correct. Because of the effects of soil confinement, the geogrids confined with soil do not undergo thermal expansion or contraction from temperature change if slippage between the soil and geogrid cannot occur. Instead of thermal strains, thermal stress or thermal force will be developed in the geogrids with the magnitude depending on the elastic properties, temperature change, and linear coefficient of thermal expansion. Key words: geogrid, strain gauge, temperature, thermocouple, thermal strain, thermal stress. Les temperatures ont ete mesurees le long de geogrilles instrumentees afin de determiner les deformations thermiques et leurs variations selon les variations saisonnieres des temperatures. Il a ete observe que l'application de la correction pour compenser les deformations induites par la temperature sur les mesures de deformations realisees avec des jauges de deformations par resistance du fil electrique (RFE) n'est pas correcte. En raison des effets de confinement du sol, les geogrilles confinees a l'interieur du sol ne subissent pas d'effets d'expansion ou de contraction thermique lorsque la temperature change s'il n'y a pas de glissement entre le sol et la geogrille. Plutot que des deformations thermiques, des contraintes ou forces thermiques seront developpees dans la geogrille, a des magnitudes dependant des proprietes elastiques, des variations de temperature et du coefficient lineaire d' expansion thermique. Mots-cles : geogrille, jauge de deformation, temperature, thermocouple, deformation thermique, contrainte thermique. [Traduit par la Redaction], Introduction The first author performed a research graduate thesis in 2003 on the long-term performance of a geogrid-reinforced test embankment constructed in 1986. Vertical and horizontal inclinometers and extensometers, settlement [...]

Incubation experiments were conducted to assess the effectiveness of N-(n-butyl) thiophosphoric triamide (NBPT) for inhibiting hydrolysis of urea in three wheat-growing soils and one pasture soil in south-eastern Australia, under a range of temperatures (5, 15, 25°C). The effectiveness of NBPT decreased with increasing temperature and with increasing ureasc activity. In the acidic pasture soil with high urease activity (186 µg N/g soil.h) and high organic carbon content (11%), NBPT (0.1% w/w urea) had little impact on urea hydrolysis rates over all temperatures, with 55% urea remaining). At 25°C in the wheat soils, NBPT slowed the rate of urea hydrolysis, but by Days 14 and 15, Additional keywords: incubation studies, NBPT, urease activity., Introduction Nitrogen (N) fertiliser use in Australia has increased from 35 Gg N in 1961 (FAO 2006) to 848 Gg N in 2007-08 (IFA 2009). Urea is currently the main [...]

Soil temperatures are related to air temperature and rainfall on the current day and preceding days, and this can be expressed in a non-linear relationship to provide a weighted value for the effect of air temperature or rainfall based on days lag and soil depth. The weighted minimum and maximum air temperatures and weighted rainfall can then be combined with latitude and a seasonal function to estimate soil temperature at any depth in the range 5-100 cm. The model had a root mean square deviation of 1.21-1.85°C for minimum, average, and maximum soil temperature for all weather stations in Australia (mainland and Tasmania), except for maximum soil temperature at 5 and 10 cm, where the model was less precise (3.39° and 2.52°, respectively). Data for this analysis were obtained from 3240 Bureau of Meteorology weather stations throughout Australia and the proposed model was validated using 5-fold cross-validation., Introduction Soil temperature influences the rate of activity of biological processes, including plant growth (Hanson and Baker 1993), development of insects in the soil (Dallwitz and Wardhaugh 1984), microbial activity [...]

We studied the soil temperature regimes of the volcanic island of Tenerife (Canary Islands, Spain), which is situated in the Atlantic Ocean between 27 and 28[degrees] N. The island is 2034 [km.sup.2] in size and its highest point is 3718 m above sea level. Direct temperature measurements were taken during a 4-yr period at 103 sites, at a depth of 50 cm, in altitudinal sequences from the north and south slopes of the island. In contrast to continental situations, soil temperature regimes from all latitudes are found within a small area of the island. Seven of the nine regimes considered by Soil Taxonomy have been identified--hyperthermic, thermic, mesic, isohyperthermic, isothermic, isomesic, and cryic--and are widely distributed according to elevation and orientation. In the mid-altitude zone on the north face, which is influenced by the trade winds, regimes typical of tropical regions were found, while above 3000-m elevation, a high-latitude regime was also described. The wide diversity of soil temperatures in such a small area is explained by the variability of a range of factors, including elevation, the orientation of the mountain systems, and the influence of the trade winds. In addition to recording the presence of temperature regimes from different latitudes in a subtropical island, we documented a cryic regime at this latitude for the first time. doi: 10.2136/sssaj2009.0436

Loss of N from fertilized agricultural soils is a serious problem that can negatively affect environmental quality. Nitrogen loss can be moderated by using slow-release fertilizer (SRF) products (e.g., those created through condensation of urea and formaldehyde) in place of 100% water-soluble N. Release of N from SRFs is affected by the soil environment. To evaluate soil effects on N release, we conducted an incubation study in which temperature and soil type were varied. Four SRFs were studied: liquid Nitamin 30L (L30), liquid Nitamin RUAG 521G30 (G30), granular Nitamin 42G (N42) (all from Georgia Pacific Chemicals, Decatur, GA), and granular Nitroform (NF) (Agrium Advanced Technologies, Loveland, CO). The fertilizers were incubated for 78 d at 20, 25, and 30[degrees]C in a sandy soil and at 25[degrees]C in a loamy soil. Differential N release kinetics of the N sources were determined by measuring N[H.sub.4]-N and N[O.sub.3]-N concentrations throughout the incubation. Net N released as a percentage of total N in the fertilizer was significantly affected by N source, temperature, time, and soil type. Increasing temperature increased net N release. The N release rate decreased in the order N42 > G30 > L30 > NF in the sandy soil and G30 > N42 > L30 > NF in the loamy soil. Overall, the release rates of these fertilizers were greater in the loamy soil. The N release characteristics determined in this study can help in the selection of the appropriate SRF source for crops grown under different soil and climatic conditions to improve N use efficiency and minimize N loss to the environment. doi: 10.2136/sssaj2008.0363

The dual-probe heat-pulse (DPHP) method is useful for measuring soil thermal properties; however, the probes of a DPHP sensor can deflect when inserted into the soil. Theoretical analysis has shown that measurements of thermal conductivity (h) should be unaffected by deflection-induced changes in probe spacing. To verify this result, the conductivities of water, dry sand, and saturated sand were measured using DPHP sensors with probes subject to inward deflection, no deflection, and outward deflection. No error in X was detected when probes were deflected inward by an amount that caused a 14% reduction in probe spacing. Outward deflection (15% increase in spacing) caused error in X estimates, but the errors were small ([less than or equal to] 0.04 W [m.sup.-1][ K.sup.-1]) and likely to be of little consequence in most applications. We conclude that estimates of X obtained with the DPHP method are largely unaffected by changes in probe spacing caused by deflection. doi: 10.2136/sssaj2010.0016N

The theory of conductive heat transfer cannot explain different attenuations of the daily amplitude of peat temperatures (Ts) in hummocks (detectable below the 20-cm depth) and hollows (disappearing above the 10+ cm depth). Large readily drained macropores in the upper fibric peat determine a large air permeability and hence may enhance heat transfer by air convection in porous media, driven by temperature gradients between hummock sides and interiors. In this study, the ecosys model was used to simulate a peat thermal regime at Mer Bleue peatland, Ontario, Canada. It was hypothesized that adding the air-convective heat transfer to conductive plus water-convective heat transfers would improve simulations of [T.sub.S]. The results for [T.sub.S], ground heat fluxes, G, and sensible heat fluxes, H, modeled with and without air-convective heat transfer were tested with continuous hourly measurements from 2000 to 2004 using thermocouples, heat flux plates, and eddy covariance. Simulated air-convective heat transfer caused an average increase in 6' and a corresponding decrease in H of ~20 W [m.sup.-2] from the simulated conductive plus water-convective heat transfer. Hastened soil warming in hummocks resulted in better agreement between measured and simulated hummock [T.sub.S] values with (RMSD of 2.23[degrees]C) than without air-convective heat (RMSD of 2.54[degrees]C). Enhanced hummock [T.sub.S] caused an indirect increase in hollow Ts in the model with (RMSD of 1.68[degrees]C) compared to without airoconvective heat (RMSD of 1.82[degrees]C). Our results suggest that air convection is probably an important mechanism of heat transfer in peat hummocks and should be included in peatland biogeochemical models. doi: 10.2136/sssaj2009.0288

Many important hominid-bearing fossil localities in East Africa are in regions that are extremely hot and dry. Although humans are well adapted to such conditions, it has been inferred that East African environments were cooler or more wooded during the Pliocene and Pleistocene when this region was a central stage of human evolution. Here we show that the Turkana Basin, Kenya-today one of the hottest places on Earth--has been continually hot during the past 4 million years. The distribution of [sup.13]C-[sup.18]O bonds in paleosol carbonates indicates that soil temperatures during periods of carbonate formation were typically above 30 [degrees]C and often in excess of 35 [degrees]C. Similar soil temperatures are observed today in the Turkana Basin and reflect high air temperatures combined with solar heating of the soil surface. These results are specific to periods of soil carbonate formation, and we suggest that such periods composed a large fraction of integrated time in the Turkana Basin. if correct, this interpretation has implications for human thermophysiology and implies a long-standing human association with marginal environments. continental paleoclimate | clumped isotopes | soil temperature | hominid | bipedal locomotion doi/ 10.1073/pnas.1001824107

Little is understood about chemical weathering processes in Alaskan arctic soils, where moisture is generally not limited but acidity varies and the average soil temperature is close to or below freezing. Weathering reactions in soil convert primary minerals into secondary clay, minerals. Silty loam textured soils from three sites in moist acidic tundra (MAT) and three sites in moist nonacidic tundra (MNT) in the northern Arctic Foothills, Alaska, were characterized with emphasis on the origin of the clay minerals. The MNT soils had a discontinuous and thinner organic layer, which leads to a deeper summer thaw and greater cryoturbation than the MAT soils. The MNT had higher cation exchange capacity and base saturation than MAT. These buffer against acidification and account for the pH differences of MAT and MNT. Other chemical characteristics including C and N content as well as Fe and Al were similar (by horizon) across the MAT/MNT boundary. X-ray diffraction of coarse (0.0002-0.002 mm) and fine clay ( Abbreviations: CEC, cation exchange capacity; MAT, moist acidic tundra; MNT, moist nonacidic tundra; XRD, x-ray diffraction. doi:10.2136/ssaj2009.0187

Human activity has changed land surfaces by converting native ecosystems to urban and agricultural land uses. This conversion has caused increases in air and soil temperatures that influence soil C and N cycling. Efforts to model changes in soil temperature resulting from urban land use change have not accounted for changes in both plant cover and land use and thus tail to produce accurate predictions at high-resolution spatial and temporal scales. We measured average daily soil temperature at a 10-cm depth at urban and rural forest and grassland sites for 8 yr in the Baltimore, MD, metropolitan area and developed a model of the average daily soil temperature that accounts for two vegetation and two land use types. Average annual soil temperature was higher in urban than rural sites under both turfgrass (15.0[degrees]C vs. 13.5[degrees]C) and forest (12.6[degrees]C vs. 12.2[degrees]C). The application of climate-change scenarios predicted by general circulation models to our soil temperature model suggested that the highest increases in mean soil temperatures will occur in August, September, February, and March, and will range from 1.2 to 2.0[degrees]C, while air temperature is predicted to change from 3.4 to 5.6[degrees]C between 2070 and 2099. The model can be used to predict the average daily soil temperature in the Baltimore area for sites with similar hydrologic and soil conditions, i.e., remote from the shoreline and characterized by loamy soils. Abbreviations: AIC, Akaike Information Criterion; BIC, Bayesian Information Criterion; GCM, general circulation modal; NCDC, National Climate Data Center. doi:10.2136/sssaj2009.0107

Feedback to climate warming from the carbon balance of terrestrial ecosystems depends critically on the temperature sensitivity of soil organic carbon (SOC) decomposition. Still, the temperature sensitivity is not known for the majority of the SOC, which is tens or hundreds of years old. This old fraction is paradoxically concluded to be more, less, or equally sensitive compared to the younger fraction. Here, we present results that explain these inconsistencies. We show that the temperature sensitivity of decomposition increases remarkably from the youngest annually cycling fraction ([Q.sub.10] < 2) to a decadally cycling one [Q.sub.10] = 4.2-6.9) but decreases again to a centennially cycling fraction ([Q.sub.10] = 2.4-2.8) in boreal forest soil. Compared to the method used for current global estimates (temperature sensitivity of all SOC equal to that of the total heterotrophic soil respiration), the soils studied will lose 30 45% more carbon in response to climate warming during the next few decades, if there is no change in carbon input. Carbon input, derivative of plant productivity, would have to increase by 100-120%, as compared to the earlier estimated 70 80%, in order to compensate for the accelerated decomposition. Key words: boreal forest; decomposition.' Finland; soil organic carbon; soil organic matter; temperature sensitivity.

Microscopic differences in soil pore water velocity cause hydrodynamic dispersion of solute transport. By analogy, thermal dispersion should be considered in soils where water and heat flow occur simultaneously. Few published data are available regarding thermal dispersion in soils. In this study, we investigated thermal dispersion influences on heat transport in saturated soils with one-dimensional water flow. A new soil container was developed to eliminate wall flow influences on saturated water flow. An inverse model was applied to obtain the thermal dispersion coefficient ([[lambda].sub.d]) by fitting the conduction-convection-dispersion (CCD) model to soil temperature change as a function of time from heat-pulse measurements. Thermal dispersion became significant when the water flux was higher than a threshold value. In the studied water flux range, the maximum contribution of hydrodynamic dispersion to effective heat conduction [[lambda].sub.d]/([lambda].sub.d] + [lambda].sub.0])' where [lambda].sub.0] is the bulk thermal conductivity] was 6, 9, and 12% in a sand, a silt loam, and a sandy clay loam, respectively. A power function relationship was established between [lambda].sub.d] and the soil water flux density ([J.sub.w]): [lambda].sub.d] = [kJ.sub.w.sup.0.9], where k is a coefficient related to soil texture. Experimental evaluation indicated that, compared with the conductionconvection model, the CCD model performed better in describing the temperature change vs. time data from heat-pulse measurements. Abbreviations: CCD, conduction-convection-dispersion. doi: 10.2136/sssaj2008.0251

Dielectric sensors have been widely used for nondestructive determination of volumetric soil water content ([theta], [m.sup.3] [m.sup.-3]). Since the output of such sensors is affected by soil temperature (T, [degrees]C), the calibration for the effect is indispensable for accurate determination of e. The objectives of this paper were (i) evaluation of the temperature effects on outputs of the commercial capacitance probes called ECH20 probes for various types of soils, and (ii) to include temperature in empirical calibration equations. Laboratory experiments were performed to obtain probe outputs at various T (5- 35[degrees]C) and e (air-dry- near-saturation), using four soils and four probe models with different oscillation frequencies (5 and 70 MHz). The results showed that the outputs linearly responded to T at constant (3 for all tested soilprobe combinations. The slope values of the linear responses to T depended on e. The curves of the output-e functions at a reference temperature (25[degrees]C) varied among the soils and probe models. A calibration equation describing the probe output as a function of e and T was derived for each soil-probe combination by combining the output-[theta] function at the reference temperature and the slope-[theta] function. The derived calibration equations substantially reduced the temperature effects on the probe outputs for all soil-probe combinations. We also briefly considered the theoretical background of temperature effects on the probe outputs based on the results from the experiments and the properties of the soils tested. To demonstrate the importance of temperature calibration, the derived calibration equations were applied to two field observations from arid reasons. Abbreviations: [S.sub.a], surface area, T, temperature; [theta], water content. doi: 10.2136/sssaj2008.0128

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.forsciint.2009.07.002 Byline: Jonathan Prangnell, Glenys McGowan Keywords: Soil; Temperature; Burial; Exhumation; North Brisbane Burial Ground; Cemetery Abstract: The effect of air and water temperature upon the decomposition of human remains and upon biological activity has been extensively studied. However, less attention has been devoted to the temperature of the soil surrounding burials, despite its potential influence upon chemical reactions involved in the decomposition of human remains, drugs and toxins, as well as upon microbial and insect activity. A soil temperature calculation equation usually employed in civil engineering was used to calculate soil temperature at various depths in a cemetery located in Brisbane, Australia, in order to explain the extensive degradation of human remains and funerary objects observed at exhumation. The results showed that for the 160 years of the site's history, ground temperature at burial level had been sufficiently high for biological activity and chemical degradation reactions to continue right up until the time of exhumation. The equation used has potential in the analysis of both cemetery and clandestine burials, since it allows ground temperature to be calculated from ambient air temperature figures, for a variety of depths, soil types and vegetation conditions. Author Affiliation: The University of Queensland, School of Social Science, University of Queensland Archaeological Services Unit, St Lucia, Queensland 4067, Australia Article History: Received 24 February 2009; Revised 30 June 2009; Accepted 1 July 2009

: To investigate the interactive effects of soil temperature ([T.sub.soil]) and nutrient supply on the responses of growth and biomass of white birch (Betula papyrifera Marsh.) to atmospheric carbon dioxide concentration ([C[O.sub.2]]), seedlings were grown under two [C[O.sub.2]] (360 and 720 µmol x [mol.sup.-1]), three [T.sub.soil] (5, 15, and 25°C initially, increased to 7, 17, and 27°C one month later), and three nutrient regimes (Low: N-P-K = 4:1.8:3.3 mg x [L.sup.-1]; Intermediate: N-P-K = 80:35:66 mg x[L.sup.-1]; and High: N-P-K = 160:70:132 mg x[L.sup.-1]) for 4 months. Low [T.sub.soil] reduced leaf and total biomass at high nutrient supply and root biomass at intermediate and high nutrient supply. There were significant three-factor interactive effects on root collar diameter (RCD), stem biomass, and leaf mass ratio. Low [T.sub.soil] reduced RCD at high nutrient supply and stem biomass at intermediate and high nutrient supply in elevated [C[O.sub.2]] while intermediate and high [T.sub.soil] enhanced them. Values of leaf mass ratio were lowest at low [T.sub.soil] and low nutrient supply in elevated [C[O.sub.2]]. The effect of [T.sub.soil] was generally insignificant at low nutrient supply, but the responses of growth and biomass remained significantly higher under high than low nutrient supply at all [T.sub.soil]. Key words: boreal forest, global change, [T.sub.soil] x nutrition, C[O.sub.2] x [T.sub.soil] x nutrition. Resume : Afin d'examiner les effets interactifs entre la temperature du sol ([T.sub.sol]) et l'apport en nutriments sur les reactions de croissance et en biomasse du bouleau blanc (Betula papyrifera Marsh) aux concentrations de bioxyde de carbone ([C[O.sub.2]]), les auteurs ont cultive des plantules sous deux teneurs [C[O.sub.2]] (360 et 720 µmol x [mol.sup.-1]) et trois [T.sub.sol.1] (5, 15 et 25°C au depart, avec des augmentations a 7, 17 et 27°C, un mois plus tard), et trois regimes nutritifs (Faible: N-P- K = 4:1.8:3.3 mg x [L.sup.-1], Intermediaire; N-P-K = 80:35:66 mg x [L.sup.-1], et Eleve; N-P-K = 160:70:132 mg x [L.sup.- 1]), pendant quatre mois. La basse temperature du sol reduit la biomasse foliaire et totale avec nutriments eleves et la biomasse racinaire avec des apports intermediaires et eleves. On observe des effets trifactoriels significatifs sur le diametre racinaire au collet (RCD), et le rapport de la biomasse de la tige sur la biomasse foliaire. La faible [T.sub.sol] reduit le RCD avec des nutriments eleves et la biomasse de la tige avec des nutriments intermediaires et eleves, avec un [C[O.sub.2]] eleve, alors que les [T.sub.sol] intermediaires et eleves les augmentent. Les valeurs de ratio de la masse foliaire sont plus faibles a [T.sub.sol] faible et faible apport en nutriments en presence de [C[O.sub.2]] eleve. L'effet de [T.sub.sol] demeure generalement non significatif a faibles apports de nutriments, mais les reactions de croissance et de biomasse demeurent significativement plus elevees avec des teneurs en nutriments elevees que faibles, a toutes les temperatures du sol. Mots-cles : foret boreale, changement global, [T.sub.sol] x nutrition, C[O.sub.2] x [T.sub.sol] x nutrition. [Traduit par la Redaction], Introduction Global atmospheric carbon dioxide concentration ([C[O.sub.2]]) has gradually risen from 280 µmol x [mol.sup.-1] in 1850 to 379 µmol x [mol.sup.-1] in 2005, and is currently increasing at a [...]

To monitor and understand the temporal variations of sound speed due to the changes of soil physical properties such as soil water potential, moisture content, and soil temperature under natural conditions, a long-term field soil survey has been conducted. In this study, transmitter and receiver acoustic probes, consisting of ten (five pairs) and five transducers respectively, were inserted into a prepared trench containing a soil-sand mixture in an outdoor test site. Five time domain reflectometers, five tensiometers, and five thermocouples were buried during the trench-filling at the same depths as the acoustic transducers. Measurements of sound speed, soil temperature, soil moisture content, and water potential were performed continuously, along with the measurements of surface temperature and precipitation over a period of 2 yr. Analysis of the data shows that there is a power law relationship between the sound speed and water potential. It is also found that the water potential is the dominant influence on the sound speed whereas the moisture content and temperature have relatively minor impacts. Brutsaert and Luthin's theory was employed to calculate the sound speed as a function of the effective stress. The theoretical predictions were compared with the experimental data and they are in good agreement. The study suggests that sound speed measurement could be used as a new and effective tool for water potential measurement. Abbreviations: LVD, laser doppler vibrometer; MASW, multi-channel analysis of surface waves.

Soil water content or potential can be adjusted in the laboratory by equilibrating the soil at different relative humidities. These relative humidities can be produced by the use of different saturated salt solutions or by heating the soil to different temperatures in a convection oven. Usually, the conditions for equilibrating the soil are expressed as relative humidities if salt solutions are used or as the temperature of drying if a convection oven is used. This dichotomy does not allow all the results to be compared or plotted on a common axis. In this paper, the Magnus--Tetens and the Arden Buck equations are used in combination with the Kelvin equation to show how the results from both types of equilibration can be presented on the same scale (e.g., water potential or pF). Two new equations show how the results from oven drying depend not only on the oven temperature, but also on the temperature and relative humidity of the air in the laboratory. For example, drying soil in an oven in one set of atmospheric conditions can produce a significantly different water potential than in different atmospheric conditions. The new equations enable the soil water potentials (or pF values) produced by oven drying to be calculated for all combinations of oven temperature and atmospheric conditions. Predictions from the equations are evaluated by comparing water retention data obtained by oven drying and by equilibration over saturated salt solutions, k is shown that the mean absolute error in gravimetric water content is 2.3 g [kg.sup.-1]. Equations are presented for the mean thickness of water films adsorbed on the surfaces of soil particles under different drying conditions. The amount of water adsorbed on particle surfaces is predicted to be zero at pF6.6.