Soil Temperature Distribution Research Articles

Soil‐Water Movement in Response to Imposed Temperature Gradients

AbstractRedistribution of soil water within insulated, uniformly packed, horizontal samples of unsaturated Columbia fine sandy loam at several soil‐water contents was studied in response to imposed temperature gradients ranging from 0.5 to 1.0C/cm. Soil bulk density and initial, transient, and final soil‐water‐content distributions were determined each 0.5‐cm along the column by gamma‐radiation attenuation. Initial, transient, and final soil temperature distributions were monitored by glass‐encased thermistors at 2‐cm intervals—both at the center and 0.3 cm from the column wall. Apparent thermal and isothermal soil‐water diffusivity values were calculated using transient water content data. The observed net water flux was found to increase with decreasing water content throughout the 0.077–0.274 cm3/cm3 range. For Columbia soil at 0.077 cm3/cm3 the observed mean net water flux across 1‐cm sections of the soil showed acceptable agreement with that predicted by the theory of Philip and deVries; Fick's law and the modified Taylor‐Cary irreversible thermodynamic equation both underpredicted the observed fluxes.

SOIL TEMPERATURE OBSERVATIONS IN WESTERN SUBURBS OF TOKYO AND THEIR STATISTICAL STUDIES (2ND REPORT): EFFECT OF SOIL MOISTURE ON THE DISTRIBUTION OF SOIL TEMPERATURE

In the previous report, the author discussed the effect of precipitation on the vertical distribution of soil temperature basing on his own observation. Since a part of the precipitation nourishes the soil moisture under the ground, it is probable that the moisture has an influence on the horizontal temperature distribution of the soil. In order to verify this fact, the author and his collaborators observed the distribution of the soil temperature at 75 cm depth using the method of moving observation. Obsevations were carried out in and around Hoya, the western suburbs of Tokyo (Fig. 1 and 2). The instruments used were thermistor thermometers for soil temperature, boringbars or -sticks, and bicycles for moving (Photo. 1 and 2). Reading of temperature was taken about 10 minutes after putting of the thermometers into the hole at 75 cm depth. Observation were made at about 80 points, favoured with the following three conditions ; bare ground, comparatively soft soil, open and sunny site. Errors of temperature readings due to the time lag caused by the moving were nearly negligible, because soil temperature at 75 cm depth shows neither daily nor interdiurnal change for a few days as reported in the previous paper. In winter, however, the interdiurnal change reaching about -0.1°C was found, so that the author made temperature adjustments by adopting a cross-check method. The meteorological conditions before, during and after the observations are shown in Fig. 3 and 6. The results obtained were summarized as follows In summer (see Fig. 5), 1. Colder areas where soil temperature is lower than 20°C exist along valleys floor with its surroudings, cultivated ground, and forests. 2. Warmer areas (higher than 21°C) are found in urbanized areas and some parts along the riverside. In winter (see Fig. 7), 3. Colder areas (lower than 11°C) are confirmed in urbanized areas and in some parts of the valley. 4. Warmer areas (higher than 12°C) exist in some parts with smaller house-density, cultivated upland and forests. Based on these facts, it may be concluded that the local horizontal distribution of soil temperature has seasonal changes, the regional difference of soil temperature is comparatively larger in summer and smaller than that of the air temperature in all seasons. The distribution pattern is relatively complicated in winter. This shows that the local distribution of soil temperature is more modified by many other factors than the solar radiation, such as river water, underground water, both of which were observed in autumn (Fig. 8). In this paper, the direct effect of the underground water on the soil temperature was not clarified, but the influence of the river water was found to some extent as shown by Fig. 10 and 11. The former was derived from above-mentioned observations of soil temperature distribution in July (T7) and December (T12), 1964. The relationship between temperature difference (T7-T12) and the distance L to the bank from the observation site are shown there. If the temperature difference is explained by the heat flux in the soil and the distance L represents soil moisture, the influence of the moisture on the annual heat exchange in soil can be shown by Fig. 10. In Fig. 11 we can find the correlation between the soil temperature and moisture which were observed in June, 1966. All of the above statements are provisional and nothing but a qualitative conclusion. So we have many important problems to be investigated. In particular, the relationship between the soil temperature and moisture should be studied from the view point of heat and water balance in the soil.

Water Movement and Loss Under Frozen Soil Conditions

AbstractSoil water and temperature distributions in a silty clay loam soil were studied in the field under freezing winter conditions. Appreciable upward water movement to a frozen zone occurred in plots in which the unfrozen subsoil water was held at tensions of less than about 2 atm. and water held at tensions of less than 5 atm. moved toward the frozen zone. It appears that the upward water movement to the frozen zone conributed to overwinter water losses since soil water losses of 0.36 and 0.50 inches were measured from those plots in which there was appreciable upward water movement. Plots containing 7.9, 6.2, 4.2, and 1.4 inches of available water before freezing occurred conserved −0.36, −0.50, 0.0, and 0.81 inches, respectively, of the 4 inches of precipitation that occurred during the winter.

Characterization of Soil Temperature Distribution from Various Tillage‐Induced Microreliefs

AbstractSoil temperature was measured where three tillage systems produced a ridge and furrow microrelief and a smooth soil surface. Corn was planted on ridges, in furrows, and on a smooth surface and with rows running in an east‐west or north‐south direction. During early growth, corn seedlings were in the warmest soil when the seed was placed in ridges running in an east‐west direction and in coolest soil when the seed was placed in a furrow such as that produced by a listing tillage system.

Microclimatological Characteristics in the Dune

It is known that the surface soil temperature in the dune shows marked increase in the day time. In order to obtain the reason of this fact, the author carried out the observations of vertical distributions of soil temperature, air temperature, humidity, wind velocity and solar radiation in August, at Skata, Yamagata Pref.The results are as follows:(1) The marked increase of surface soil temperature in the dune depends mainly on decrease of thermal conductivity (heat conductivity) of the soil, especially in surfacelayer, lower value of heat capacity of that and the increase of heat flux to the soil introducing by decrease of heat loss by evaporation.(2) It was recognized that the surface soil temperature in the dune can be computed from meteorological data by using formula (24) and (27) as shown in Table 4.

A Measurement of Heat Flux to the Soil

In order to investigate the heat flux to the soil, the author carried out the observatious of soil temperature, the volume percent of dry soil, water and air be contained withn the soil from November to December in 1957 at Tateno, Ibaragi Pref.The results are as follows;1) The heat capacity (ρc) of the soil is calculated form following formla indirectly, ρc=ρ(0.20x1+x2+0.24x3)where x1, x2 and x3 be observed exactly by using volumenometer are volume percent of dry soil, water and air be contianed withn the soil, respectively, ρ is the density of the soil.The heat capacities of some soils is shown in Tab. 1., and the daily course of the heat capacity of the soil layer from 0cm to -1cm is shown in Fig. 1. and it is recognized that the heat capacity shows higher value at about sunrise and lower at evening.2) The heat fluxes to the soil which was calculated from the distributions of soil temperature is compared when the daily change of heat capacity in the soil surface layer was ignored or not, and it is certainly that both values are nearly equal as shown in Fig. 2.3) Considerable agreement of the heat flux to the soil be calculated from the temperature distribution with that directly by heat flow meter was found as shown in Fig. 3.

Some characteristics of temperature distribution in the paddy field being continuously irrigated with cold water

In the paddy field being irrigated continuously with cold water, horizontal distribution of both water and soil temperature at nine points and vertical distribution of air temperature at three points, i.e. water inlet, center and water outlet, were measured on a clear day in July and August, 1952.The results obtained are as follows:1) On a sunny day in summer, cold water (14-20°C) is warmed up strikingly in the paddy field, although the sunlight is restricted by the plant cover. On 27th of July, for example, water temperature of 34°C was observed at the water outlet.2) In each figure of horizontal distribution of water and soil temperature for every hour, isothermal lines are represented by concentric circle with the center at the inlet.3) Diurnal movement of isothermal lines in those figures has a interesting periodicity, and between 10 and 15m from the inlet there is a noteworthly zone showing the maximum of rising up of water temperature.4) Diurnal changes of vertical temperature distribution at three points with different water temperature are shown in fig. 4. This figure show that types of vertical distribution of temperature in paddy field are closely related to size and density of rice plant and are modified remarkably by water temperature The nfluence of water on the temperature of air layer above it is found to be higher in night than in day time, and the height of influence goes up with growth of the plant.

Influence of the different soil temperature-systems on the growth of the sweet potatos

We studied the growth of the sweet potatos in the field plots of the different soil temperature distributions which were installed the thermoelectric wires at the different depths in the soil.The plots whose grounds were warmed by the thermoelectric wires were worse for the growth of the tuberous root than the standard (not warmed), though they were better for the growth of the stems and leaves above the ground. Especially the plot warmed at 10cm depth, where is ordinarily to be the center of the tuberous roots of the sweet potatos under the ground surface, produced very poor tuberous root.Thus, it was proved that the distributions of the temperature in the soil (soil temperature-systems) have much significance on the tuberization of the root of the sweet potatos and the high temperature of the subsoil layer is wrong for the growth of the root tuberous, as the theory of the effect of the temperature-systems suggested by NISHIUCHI.