Journal of Agricultural Meteorology
Online ISSN : 1881-0136
Print ISSN : 0021-8588
ISSN-L : 0021-8588
Volume 53, Issue 3
Displaying 1-11 of 11 articles from this issue
  • Yoshinobu HARAZONO, Qingyun CHEN, Mayumi YOSHIMOTO
    1997 Volume 53 Issue 3 Pages 175-183
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
    Light transmittance, temperature and humidity of greenhouses covered with three PolyOlefin films of PO1 (Mikado Chemical M.F.G. Co., Super solar 0.15mm in thickness), PO2 (Sumitomo Chemical Co., Cleantate-LF, 0.15mm in thickness), and PO3 (Mikado Chemical M.F.G., Co., U-lack, 0.1mm in thickness), and a ploy vinyl chloride film PVC (Mitsubishi Chemical MKV Co., Clean Ace-CPM, 0.13mm in thickness) were examined to elucidate the differences of microclimate inside the greenhouses. All the films were covered in October 1993 except PO3 which was covered in October 1994. Several kinds of vegetables such as spinach, daikon-radish, Chinese-cabbage and red-radish were cultivated under usual management in each autumn-winter-spring season. Air temperature, humidity, solar rediation, and soil heat flux inside and outside (control) each greenhouse were measured during every winter-spring season. Dewdrop and/or condensation water on the covering film and the water content in the air were measured in order to check the humidity conditions in each greenhouse. The relationship between light transmittance and the dewdrop on films of the greenhouses was analyzed using the data obtained mainly in 1995-1996 season and 1997. The main results are as follows.
    1. Transmittance of solar radiation of PO1, PO2, PO3-greenhouses was 76.7%, 79.7%, and 63.5%, respectively, while that of the PVC-greenhouse was 71.6% at early March in 1996.
    2. Ventilation rate of PO1 and PO2-greenhouses was high but that of PVC was very low. The differences in ventilation rate were caused by different draft condition of each greenhouse.
    3. As compared to other three greenhouses, air temperature difference between the inside and outside of the PO3-greenhouse was lower by 2-4°C during daytime, resulting from the heavy dewing on the covering film.
    4. Average dewdrop on the films of the PVC and PO3-greenhouses was from 140-250g/m2 on cloudy day, while that of the PO1 and PO2-greenhouses was less than 40g/m2. Dewing on the greenhouse films reduced the transmittance of the solar rariation at a rate of exp (-0.9d), where d is equivalent water film thickness of dewdrop and/or condensation.
    5. An empirical equation was obtained using the relationship between light transmittance and the dewdrop thickness in order to estimate the air temperature difference between the inside and outside of greenhouse. Estimated values agreed well with measured values, suggesting that the effect of the dewdrop on the heat budget of the greenhouse can be quantified accurately.
    6. High level of dewdrop was caused by a lack of the drip control performance (runoff function) of films which decreased light transmittance, thereby increasing humidity and decreasing air temperature inside greenhouses.
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  • Yasushi ABE, Kyoichi OTSUKI, Makio KAMICHIKA
    1997 Volume 53 Issue 3 Pages 185-190
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
    It is well known that soil water content at the surface of sand increases at night, which is dry in the daytime. The mechanism of this phenomenon, however has not quantitatively clarified because continuous measurement of nighttime soil water content is very difficult. Thus, in this study, the method to estimate nighttime surface soil water content was examined by using the meteorological and soil physical data measured at Tottori sand dune in 1995. Albedo of the infrared radiation and thermal conductivity of the sand surface, which are readily calculable, were selected as the parameters of the estimation equation. Albedoes can calculate from the surface temperatures of sand measured by thermocouple and radiation thermometer, and sky temperature measured by radiation thermometer. Thermal conductivities can calculate from the radiation balance, heat balance, and temperature gradient at soil surface. The results show that thermal conductivities would give satisfying estimations of surface soil water content of sand surface.
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  • Masaichi NAKAHARA, Yoshio INOUE
    1997 Volume 53 Issue 3 Pages 191-199
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
    An application of water stress to tomato plants is effective for increasing fruit-brix, but diagnostic information is essential for the optimum irrigation management. The applicability of infrared thermometry to the water-stress management in tomato cultivation is investigated. Leaf temperatures with the infrared thermometer and thermography, physiological response, growth and fruit quality were measured in five differentially-irrigated tomato plants; a well-watered plot irrigated with 90% of the potential water uptake, and four types of water-stressed plots, i.e., the combination of two levels of irrigation water (30% and 60%) and two treatment periods (12 days and 53 days). The potential amount of transpirational water uptake could be reasonably estimated by a subirrigation apparatus. A significant increase of the fruit-brix was found in the water stressed plots, especially in those with severer and longer stress treatments. The infrared thermal imagery was shown to be effective in the visual detection of water-stressed tomato plants. Photosynthesis and transpiration rates were significantly lowered in the water-stressed plots and were closely coupled with the elevated canopy temperature or less canopy-air temperature difference, which can be measured by the infrared thermometry on remote and real time bases. Results suggested that the management of water-stress in the greenhouse fruit-vegetables could be one of the most feasible applications of infrared thermometry.
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  • A.F.M. Saiful ISLAM, Yoshiaki KITAYA, Hiroaki HIRAI, Masanori YANASE, ...
    1997 Volume 53 Issue 3 Pages 201-207
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
    A concept of the hydroponic technique was applied to sweetpotato cultivation under field conditions in a wet lowland. Three easily available indigenous materials, rice straw, wheat straw and rice husks, were placed in soil ridges to make sufficient aerial spaces in the soil for better tuberous root development. The materials were used either unmixed with soil (the Mass treatment) or mixed with soil (the Mixture treatment). Water depth between the ridges was kept at 20mm throughout the growing period in order to imitate the wet soil conditions in tropical and subtropical lowlands. The growth characteristics and yield of sweetpotato grown in the Mass and Mixture treatments were compared with those grown in a conventional control. The fresh and dry weights of the total phytomass per plant were greatest with the Mass treatment using rice husks. The fresh and dry weights of above-ground parts in the Mass treatments were approximately 0.7 times those in the control. On the other hand, the fresh and dry weights of sub-ground parts in the Mass treatment using rice husks was 4.1 times greater than those in the control. The Mass treatment using rice husks gave 5.8 times greater fresh and dry weights of tuberous roots than in the control. The edible biomass (tuberous roots) index obtained with the Mass treatment using rice husks (61.4%) was 4.4 times that in the control.
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  • Daiyu ITO, Kyoichi TAKAHASHI
    1997 Volume 53 Issue 3 Pages 209-215
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
    Soil respiration rate was monitored during a period of one year from 1990 to 1991 in a mulberry field of volcanic ash soil containing 4.5% carbon in Central Japan, where 1.0kgm-2 of fresh manure was supplied every year. Alkali absorption method using a sponge disc as absorbent holder (Sponge-AA method) was mainly adopted, but the energy budget method and open-flow chamber method were also applied because the Sponge-AA method has been reported to overestimate soil respiration.
    It was found that when the Sponge-AA method was applied soil respiration was overestimated by 2.4 and 3.1 times in summer and winter respectively, compared with the other two methods. Calibrated annual soil respiration was 2.29kgCO2m-2.
    Soil respiration rate was mainly affected by the air temperature. Both instantaneous and daily mean respiration rates increased approximately to 1.8 times when the air temperature increased by 10°C; except in summer. Soil respiration rate was sometimes considerably suppressed during or immediately after heavy precipitation, and enhanced from December to February due to manure supply and litterfall.
    The estimated amount of decomposed organic materials was equivalent to, or slightly exceeded the amount of inputted materials.
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  • Hiroaki KAMIGUCHI, Synji TAKAHASHI, Pei MING Wu, Shoin YAGI
    1997 Volume 53 Issue 3 Pages 217-225
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
    Using a three-dimensional local-scale climate model developed in the Applied Meteorological Division, Japan Meteorological Agency, a numerical simulation of thermal belt is carried out. Numerical simulations are made using a personal computer with an ideal mountain. Simulated temperature field qualitatively represents several features of observed thermal belt in some literature. Computed surface temperature difference between on the slope and on flat surface is about 2°C in maximum and a center of the thermal belt appears at about 100m level on the mountain slope.
    The formation mechanism obtained through analyses of calculated results is as follows.
    Though the lower atmosphere is cooled on the mountain slope, as well as on the flat surface, due to turbulent heat transfer to more cooled ground surface just after sunset, cooled air subsides and it forms a circulation of mountain breeze which carries relatively warm air to the lower air layer. In the analysis of calculated cooling rate upon the slope, advective warming by a system of mountain breeze compensates turbulent transfer (cooling), so that, the air in not cooled strongly through the night. On the other hand, the air upon the flat surface where mountain breeze does not penetrate is constantly cooled by both processes of turbulent transfer and radiative cooling. The temperature difference between slope and flat surface makes thermal belt. Wind speed of the mountain breeze has a maximum during a few hours after sunset and is becoming to be weaker through night time. Because the breeze circulation on the lower part of the slope diminishes relatively, decrease in advective warming cause upper slightly of thermal belt.
    Intensity of the thermal belt, defined by a difference between maximum temperature on the slope and minimum temperature on the flat surface, and height of the thermal belt depend on horizontal and vertical size of mountain. The narrower mountain seems to make the more intense thermal belt.
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  • Tadashi TAKAKURA
    1997 Volume 53 Issue 3 Pages 227-231
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
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  • Wonsik KIM
    1997 Volume 53 Issue 3 Pages 233-236
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
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  • Yoshinobu Harazono
    1997 Volume 53 Issue 3 Pages 237-242
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
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  • Testsuo Sekiyama
    1997 Volume 53 Issue 3 Pages 243-246
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
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  • Environmental and Vegetation Biomass Information at the Cultivated Land
    Working Group of Meteorological Improvement Studie
    1997 Volume 53 Issue 3 Pages 247-249
    Published: September 10, 1997
    Released on J-STAGE: February 25, 2010
    JOURNAL FREE ACCESS
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