Soil Temperature Distribution Research Articles

Predicting soil temperatures under a ridge-furrow system in the U.S. Corn Belt

A model is presented for predicting hourly soil temperatures under bare and residue plus plantcovered east-west oriented ridges in the Northern U.S. Corn Belt. The model is based on the implicit finite difference solution of a one-dimensional heat-flow equation. Two-dimensional soil temperature distribution under a ridge-furrow system is simulated by solving the one-dimensional heat-flow equation in vertical and horizontal directions, alternatively. Inputs needed for simulation are thermal diffusivity, and initial and boundary conditions. A procedure is suggested for estimating hourly upper boundary temperatures from daily maximum and minimum air temperatures. A constant temperature at the bottom boundary was justified by simulating soil temperatures in a deep profile. In general, the predicted soil temperatures under the bare ridge-furrow surface were within 2°C of the measured values; however, at some depths differences were as great as 4°C. Considering that soil temperatures are generally inputs to models (crop emergence and plant growth, nitrogen transformations and chemical degradation) that use at the minimum a daily time step, errors of 2–4°C in daily soil temperatures, in many cases, will lead to relatively minor errors in the final prediction of higher order processes.

Methane emissions from the Florida Everglades: Patterns of variability in a regional wetland ecosystem

Natural wetlands are presumed to be major sources of atmospheric methane, but current estimates of the global wetland emission vary by almost a factor of 20. Estimates of global source strengths are based on extrapolation of in situ flux measurements to large areas occupied by broad classes of wetland environments, and recent efforts at refinement of these estimates have concentrated on improving inventories of the global distribution of major wetland types. An additional potential source of uncertainty which has not been quantified is regional scale variability in emission rates within the major wetland types. We conducted an experiment which examined the spatial variability of methane flux within a large regional wetland system, the Florida Everglades. We also investigated the association of flux variability with relevant surface characteristics such as soil thickness, water depth, soil temperature, and vegetative community distribution. Unit area methane flux to the atmosphere from water‐saturated Everglades environments, measured in situ, varied over more than an order of magnitude (4.2 to 81.9 mg CH4/m2/d), depending on which habitat component of the ecosystem was sampled. Observed physical characteristics of the surface (water and soil depth, soil temperature) were not quantitatively associated with the variability in flux rates. However, the distribution of vegetative community types provided an empirical indicator of flux, permitting an inventory of emissions to be based on mapping of regional vegetation patterns. Use of high‐resolution, orbital remote sensing data helped reduce uncertainty in the emission inventory of the Everglades by directing in situ sampling efforts to important habitat types and by providing a means for calculating area‐weighted mean flux for the system as a whole. The results indicated that spatial variability in flux within a major wetland ecosystem can introduce significant uncertainty in extrapolations to larger areas, even if the extent of the major ecosystem itself is well known. The results also suggested that the response of total ecosystem flux to changing water level is not a linear function of flooded area, but is damped, with regional flux at lowered water levels decreasing proportionally less than flooded area. Both sources of variability can be addressed by the combination of remote sensing and in situ techniques we have employed in the Everglades.

Soil energy balance analysis of a solar greenhouse

An experimental investigation was carried out to determine whether sufficiently high temperatures are developed at a greenhouse's soil surface, during late summer (when greenhouses are not used in Mediterranean regions for cultivation), to use it for grape drying. The greenhouse soil temperature distribution and heat flux were calculated numerically as a function of time and space. Calculated and measured data compared well. A numerical method is also proposed to analyse and calculate the energy balance of the greenhouse's soil surface from a minimum number of measurements. The method is based on the heat stored in the soil surface layer during short time intervals. The method was applied to greenhouse soil and good results were obtained. The results are promising for the use of greenhouse soil surfaces for grape drying.

Problems related to analysis of mesoclimatic features in regions along state borders

BIOGEOGHAPHIA — vol. XIII - 1987 Biogeografla delle Alpi Sud-Orlentali Problems related to analysis of mesoclimatic features in regions along state borders ANDRE} HOCEVAR Agr0I20I7zy Depczrtme/zt, Edvard KardeZj’.t UIzz'1Jerrz'ty of Ljulaljozmz SUMMARY The needs for analysis of -climatic features in mesoscale are stressed. They must be known through studies of various practical problems in open areas in the regions along state borders, as well. Analysis of climatic features is based on meteorological observations obtained in different countries. In connection with this the following problems are discussed, that is, to obtain the needed data from foreign countries, how to get a good comparison of different observation techniques used in different countries, Some illustrations of these problems are shown and proposals for their practical solution are given. INTRODUCTION The analysis of climatic features in macroscale has been successful since the regional climatology developed. Borders among states did not influence them in spite of the fact that the original data on which they are built up came from different climatic net works, different time spans, and are _ob- tained with different observation methods respectively and that they are of- ten observed with different instruments. This is not the case with the analysis in mesoscale, with linear dimensions up to 16 kilometers, particulary in a complex terrain. And just such analyses are nowadays needed at studies in landscape ecology (Gams, 1986), ecosys- tem (Hocevar, 1986), air pollution (Petkovsek, 1978) and others, respectively. Distribution of winds, air temperature, soil temperature, radiation and other meteorological elements have to be known as functions of the terrain as pre- cise as possible (Hocevar, 1981). At this point various troubles caused by the presence of the state border show up. These troubles will be discussed, some examples will be given and some proposals for their practical solution will be suggested. PROBLEMS Nowadays the studies of climatic, features in mesoscale are still based mostly on surface observations of meteorological elements in spite of the fact that remote sensing could be helpful as well (Tretjak et al., 1985). Only the troubles connected with the first group of observations will be discussed here. 285

Temperature and Water Profiles During Diurnal Soil Freezing and Thawing: Field Measurements and Simulation

AbstractAgricultural soils of the inland Pacific Northwest undergo frequent freezing and thawing during the winter and early spring. Repeated freezing and thawing of the soil surface may accelerate breakdown of soil aggregates, resulting in decreased water infiltration, and erosion resistance. The objective of this research was to simulate soil temperature and water distributions in a field soil during freezing and thawing. A finite difference numerical model was used to simulate soil temperature, depth of freezing, and water movement. Field measurements of soil temperature, ice and water content, and freezing depth in a bare surface treatment were used to validate the simulation model. The model couples heat and water flow equations by the change in soil ice content. An experimental relationship between unfrozen water content and degrees below freezing was used to estimate the change in soil ice content. Soil heat and water flux during 7 h of freezing followed by 12 h of thawing were simulated for two different days when the soil froze to a depth of 1.5 cm, Test 1, and 0.75 cm, Test 2. Simulated maximum frost depths were 1.4 and 0.8 cm for the respective tests. Simulated ice and water content of the 0‐ to 1‐cm soil layer, at the time of maximum forst penetration was 0.46 and 0.41 cm3/cm3, which compares to measured values of 0.49 and 0.49 cm3/cm3 for the respective tests. Correlation of measured soil temperature and simulated soil temperature at the 1‐cm depth was 0.99 for both tests. Standard deviation of the differences between measured and simulated temperature at the 1‐cm depth was 1.04 and 0.29 °C for the respective tests. These results support the validity of this modeling approach for diurnal simulations of heat and water flux, near the surface, in freezing and thawing soil.

HVDC ground electrode heat dissipation in an N-layer soil

The temperature distribution in an N-layer soil, due to high-voltage direct-current (HVDC) injection via ground electrodes, was computed using finite-difference methods. The temperature profiles for various ground electrode shapes buried in a two-layer soil were computed using these same techniques. The results obtained were then compared with results obtained experimentally in the laboratory. A sensitivity analysis was performed on the effect of the height of the top layer of a two-layer earth model. The computed results agree very well with those obtained experimentally. The effect of varying the height of the top layer of a two-layer earth was then investigated. The computations indicate that the temperature can be predicted as a function of this height. >

MODELLING APPLIED TO THE ANALYSIS OF CROP–PEST-MANAGEMENT INTERACTIONS

AbstractFusarium attacking the roots of Douglas-firs in a forestry nursery was the focus of a computer simulation model that was tested against several years of nursery disease observations. Soil temperature, seedling growth, disease spread, and inoculum density and distribution were studied and their effects on measures to control Fusarium root rot were simulated. Interactions of these factors in space and time were examined from seedling germination to end of the growing season. The results from the model indicated that low soil temperature at the beginning of the growing season, rapid seedling growth, and reduction of disease inoculum levels in the upper soil horizons were the optimum prescription for disease reduction.

フィルムマルチ下地温の水平方向のバラツキとマルチ効果

フィルムマルチ下地温の水平方向のバラツキとマルチ効果

Effect of Phenylphosphorodiamidate on Ammonia Volatilization as Affected by Soil Temperature and Rates and Distribution of Urea

AbstractLaboratory incubation studies were conducted to evaluate the ability of phenylphosphorodiamidate (PPD) to inhibit urea hydrolysis and control NH3 volatilization losses. Complete hydrolysis of the uninhibited urea occurred within 8 d at all temperatures studied, and resulted in volatilization of more than 25% of the applied N within 10 d. Application of 20 mg PPD kg−1 of soil essentially prevented urea hydrolysis and resultant NH3 losses for 1, 2, 4, 8, and 17 d at 35, 25, 15, 10, and 5°C, respectively. This delay in the onset of NH3 losses due to PPD application kept NH3 losses during the first 10 d to <7% of the applied N at the three lower temperatures, but had little effect upon NH3 losses at 25 and 35°C. Such limited effectiveness of PPD at higher temperatures will no doubt reduce its utility for application to soils with surface temperatures above 25°C. Application of lower concentrations of urea gave reduced NH3 losses, both with and without PPD, likely due to a greater ability of other N transformations to compete for the reduced ammonium pools. Ammonia losses were also reduced, with and without PPD, when the urea was distributed throughout a larger soil volume, presumably due to a greater proportion of the urea being hydrolyzed below the immediate soil surface.

アカマツ種子の発芽を可能にする有効積算地温とその全国分布

The effective cumulative soil temperature in relation to the potential germination of P. densiflora seed was investigated and the results are presented in this study. The laboratory experiment was carried out in the chamber at 5°C, 8°C, 10°C, 15°C, 20°C, 25°C, 30°C and 35°C under both light (3, 000 lx) and dark conditions. The daily germination rate was observed. Initial effective cumulative soil temperature was fixed at 5°C, because the seeds did not germinate at 5°C. From the laboratory experiment at 8°C, 10°C and 15°C, it became obvi ous that, from 75°C•day to 200°C•day (germination period) the P. densiflora seed germinates. Five-day periods of effective cumulative soil temperature, 75°C•day are estimated from the data of the geographical distribution of soil temperature, which is considered to be the beginning of the P. densiflora seed germination in various places. As a consequence, the following facts have been observed (Fig. 4(a)): The first five-day period line of May passes through the southern area of Hokkaido. The first five-day period line of April passes through the Kanto district, Nagano, Gifu, the southern area of Fukui, Tottori Prefectures and Oki Island. That line of March passes through Izu Peninsula, Shizuoka Prefecture, Kui Peninsula, Seto Inland Sea and the central area of Kyushu. The line of February passes through the southern edge of Shikoku and the southern area of Kyushu. Next, the five-day periods of the effective cumulative soil temperature of the ending of the P. densiflora seed germination, that is 200°C•day, are worked out and the results are as follows (Fig. 4(b)): The first five-day period line of June passes through the northeast of Hokkaido. That of May passes through Miyagi, the central area of Yamagata Prefectures and the mountainous area of Jyo-shinetsu. That line of April passes through the south of Honshu, Seto Inland Sea and the central area of Kyushu. The line of March passes through the southern edge of Kui Peninsula, Shikoku and Kyushu. Germination period of P. densiflora seed, that is the period from 75°C•day to 200°C•day, is shorter in northeast Japan compared with that of southwest Japan (Fig. 4(c)). Therefore, there are two deficits in northeast Japan, those are, first the germination time is later and the second the germination period is shorter than in southwest Japan.

Corn Emergence as Influenced by Soil Temperature, Matric Potential, and Aggregate Size Distribution

The effects of soil physical parameters on corn (Zea mays L.) emergence were determined in a growth chamber experiment. The treatments included three different soils, four soil temperature regimes (5–15, 10–20, 15–25, and 20–30°C), four soil matric potentials (−10, −33, −100, and −500 kPa), and seven aggregate size distributions (geometric mean diameter = 0.5, 1.0, 1.9, 3.6, 5.6, 6.8, and 11.1 mm). Corn was planted at 50 mm depth in soil aggregate mixtures contained in aluminum cylinders 152 mm in height by 76 mm inside diameter. Cylinders were placed in a growth chamber with a 10°C diurnal fluctuation and time to corn emergence was determined. Based on the growth chamber study, guidelines are developed that define best seedbed conditions for corn emergence. Time to corn emergence was influenced by the independent variables in the following order: soil temperature » soil matric potential > soil aggregate size distribution. Emergence time was related to soil temperature by a power function. Corn emergence was most rapid at the warmest soil temperature (20–30°C) when soil moisture was at or above field capacity and when aggregate size distribution corresponded to a geometric mean diameter between 1.0 and 6.8 mm. Time to corn emergence was less than 21 d for all soils and matric potentials when mean soil temperature was at least 15°C. The negative effect of low soil temperatures on corn emergence was partially compensated by high soil matric potential. A corn emergence model was developed from the relationship between percent emergence and growing degree days at the seed zone depth. Relationships between percent emergence and seed zone growing degree days were approximately the same for three soils and varied with the soil matric potential. The corn emergence model indicated a requirement of 59, 62, 67, and 76 seed zone growing degree days for 75% corn emergence at soil matric potentials of −10, −33, −100 and −500 kPa, respectively. The model was tested using corn emergence data from a field study consisting of eight combinations of three tillage and three surface residue treatments. Field data on corn emergence corresponded well with the growth chamber results obtained with constant diurnal soil temperature cycles. Heat units needed for 75% corn emergence under various tillage and residue conditions at field moisture content (matric potential = 0 to − 10 kPa) corresponded to 52 seed zone growing degree days. This corn emergence model should be useful in predicting optimum planting dates based on measured or predicted historical seed zone temperatures.

Soil Temperature in a Row Crop with Incomplete Surface Cover

AbstractA method is presented to predict soil temperature distribution between rows of crops that partially shade the soil surface. The method combines a model for predicting time and location of soil surface shading with a model for two‐dimensional soil heat transfer. The track of shadow model is general, and requires only plant shape parameters, field location coordinates, row spacing, and row direction to predict soil surface shading as a function of time. The soil heat transfer model is an explicit finite difference approximation of the transient conduction equation, allowing for time and space dependence of soil thermal properties. The surface boundary temperatures are computed by partitioning the surface net radiation into the sensible air, latent, and ground heat flux components. Standard meteorological inputs required to compute the energy partitioning are global radiation, air temperature and humidity, and windspeed. Observed and computed temperature distributions show agreement for a 1‐d simulation. To predict surface energy partitioning and soil temperature accurately for longer periods of time, the method must be expanded to account for water transport.

Observed and Predicted Two‐Dimensional Soil Temperature Distributions Under a Row Crop

AbstractA two‐dimensional soil heat transfer model was developed to compute the soil temperature distribution between rows of crops which partially shaded the soil surface. The model is based on an explicit solution, using CSMP, of the heat conduction equation and allows for time and space dependence of soil thermal properties. Measured soil temperatures were taken as input for the upper boundary. Computed temperature distributions were compared with temperatures measured below a trickle irrigated row crop, which only partially shaded the soil. There was a large variation in the surface and near surface soil temperatures with distance from the row. Ranges of the daily surface soil temperature waves were about 5°C directly below the crop and about 40°C between two crop rows. Around noon the horizontal soil heat flux in the upper soil profile was much greater than the soil heat flux in the vertical direction. Better agreement was obtained between measured soil temperatures and predicted soil temperatures when horizontal heat flux was taken into account.

Temperature distributions around buried pipe networks in soil with a temperature dependent thermal conductivity

The temperature distribution in soil around a network of subsurface horizontal warm water pipes was investigated. Computations of soil thermal conductivity revealed a linear dependence on temperature due to the presence of moisture and induced vapour diffusion within the pore space. Solutions of the temperature distributions around various buried pipe networks were obtained in closed forms and numerically. Experiments were conducted with a single buried pipe. The data showed that the present model yields better predictions than previous constant property models. Analyses were extended to account for effects of desiccation around the heated pipes. The results are applicable in horticulture for improved designs of soil warming networks.

Temperature and Moisture Regimes in Soils Mulched with Transparent Polyethylene

AbstractA numerical one‐dimensional model was developed in order to study the effect of soil mulching with transparent polyethylene film upon the soil moisture and temperature regimes. Environmental conditions, soil physical characteristics, and optical properties of the cover are considered. Calculated moisture and temperature profiles were compared with observed ones in experimental field plots. It was shown that soil moisture and temperature distributions are significantly influenced by the polyethylene mulch. The results indicate that the numerical model accurately predicts the soil moisture and temperature regimes in two tested soils. In both a Rehovot sand soil and a light clay soil, experimental and calculated results showed that the temperature maxima of the soil increase with increasing soil moisture content. In the light clay soil both the experimental and numerical results showed that the tarping of the soil with transparent polyethylene caused a significant increase in soil moisture in the upper soil layer. At close to air‐dry moisture content, the maximum temperature of the light clay soil indicated a much higher value than the wettest mulched plot of the same soil. Physically based explanations are given for the measured and computed results.

菅平における地温分布の年変化と地表被覆

It is well known that heat input at the surface and the thermal properties of the soil control the variations of soil temperature according to time and space. However, observations of soil temperature distribution were not so often made as those of air temperature. The author has investigated the influence of vegetation and snow cover on the soil temperature distribution and its annual variation.Observation were carried out at the Sugadaira Montane Research Center of the University of Tsukuba in Nagano Prefecture, Central Japan from November 1976 extending over 25 months. Soil temperature of 50cm depth was measured at 34 points beneath grassland vegetation (Miscanthus sinensis Stand) and forest vegetation (Pinus densiflora Stand) using the method of moving observation. The instrument used is the thermister thermometer for soil temperature.The results of observation indicate that distribution pattern of 50cm depth soil temperature is well coincident with the map of vegetation from May to November. During continuous snow cover period, December to April, it is not accord with the distribution of vegetation. According to disappearence time of snow cover, soil temperature becomes minimum in March or April, while it is maximum in August at all observation points. Just after snowmelt soil temperature begins rising suddenly. Therefore, annual soil temperature variation is affected by snowcover and thaw during snowcoverage season.

Soil Heat Transducers and Water Vapor Flow

AbstractThe heat flow through a silt loam, silty clay, and loamy sand were measured in a calorimeter at 7 and 36°C under matrix potentials near −0.3 bars. The transient thermal conductivity probe, the heat flux transducer, and deVries's theoretical method all gave low values of the apparent thermal conductivity at 36°C. An empirical correction was proposed for deVries's method that improved its agreement with the observed conductivities. The thermal vapor diffusion coefficients for the three soils were then calculated from his equation and compared with experimental values from the calorimeter. It was also shown that the thermal water vapor flow can be estimated if one knows the soil's saturated thermal conductivity, quartz content, water content, bulk density and temperature distribution.

A Descriptive Model for Predicting Spring Emergence of Heliothis zea Populations in North Carolina 12

A conceptual model is formulated which describes overwinter developmental rate for Heliothis zea (Boddie) pupae. An analytic function for prediction of spring emergence as a function of temperature is developed through the technique of matched asymptotic expansions. The resultant model is fit to observed post-diapause developmental rates measured at various constant temperature regimes. From these data, parameters were estimated for 10, 50, and 90 percentile emergence. A field spring emergence model is presented which includes the temporal variation in post-diapause morphogenetic development, the spatial distribution of overwintering pupae in the soil, and the spatial/temporal distribution of soil temperature. Model results are compared to an observed field emergence.

Fundamental Studies on Rhizosphere Environment Control (2)

The applicability of the P.I.D. control algorithm for an identified soil temperature system1) was investigated using both experiments and computer simulations.Results:1) The P.I.D. soil temperature control experiments showed that although every four optimally adjusted P.I.D. parameter sets lead the controlled variable, (the soil temperature at the logarithmical middle point) to the stepwise desired value in the steady state, the transient response curves are differ greatly when four sets of optimal P.I.D. parameters from the C.H.R. method are used. The simulated P.I.D. soil temperature controls were similar to the above experiments except for slight differences in detail. This implies that investigations of P.I.D. soil temperatue control systems can be carried out using computer simulations composed of the mathematical model for a soil temperature system developed in a previous paper1) .2) Not only was it determined that P.I.D. soil temperature control can be performed using a digital computer, but that the P.I.D. soil temperature control system, itself, and the soil temperature distributions can be investigated with computer simulations while the soil temperature is P.I.D. controlled, if the digital computer possesses the state space simulation model of the P.I.D. soil temperature control system developed in the present paper.

Soil Heating Studies with Cool Season Turfgrasses. I. Effects of Watt Density, Protective Covers, and Ambient Environment on Soil Temperature Distribution1

AbstractElectrical soil heating studies were conducted from 1967 to 1969 for the purpose of determining wattage and soil temperature requirements for establishment and growth of several turfgrasses during winter. Studies also included influence of Protective Covers, fertilization and heat distribution in the soil. Cables were installed 15.2 cm deep and 30.4 cm apart to provide wattages of 54,108 and 162/m2. Power was supplied from early December until normal spring green‐up. Thermostats located below the turf at the soil surface controlled cable operation. Heating densities of 108 W/m2 or greater were required to maintain soil temperatures near 8 to 10 C during the winter. Temperature distribution curves at several depths showed good thermoconductivity of the soil. Temperature changes near cables were closely linked to power input; near the surface, air environment had the greatest impact. In unheated soil, a lag occurred in diurnal temperature changes which were a function of soil depth. Heat losses were measured in deep soil strata. Block polypropylene screens of 55 and 73% shade used for protection increased heat retention and reduced heating requirements over unprotected turf.