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Volume 64, Issue 4
Displaying 1-12 of 12 articles from this issue
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Review Papers
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Richard ALLEN2008 Volume 64 Issue 4 Pages 191-204
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESSQuality assessment and control (correction) of weather data are essential to calculation of accurate and representative reference ET and to avoid biases in data. Simple visual (graphics-based) methods are presented that can be used to screen and correct large amounts of data. In the case of solar radiation, theoretical clear sky solar radiation is compared against for daily and hourly time periods. A simple least-square multiple linear regression method appears to be helpful in identifying components of eddy covariance that need adjustment to close the energy balance. The method offers an alternative to distributing error according to Bowen ratio and it provides corrections (regression coefficients) for H, LE and for soil heat flux.View full abstractDownload PDF (1331K)
Full Papers
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Hisato ICHIKAWA, Hirakazu SEKI, Shinichi TAKAMI2008 Volume 64 Issue 4 Pages 205-213
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESS“Solar Pump” is a new concept of solar still where water is distilled as well as transported by solar energy. In the water reservoir, a column of porous material is immersed, which absorbs and transmits water. Water thus transported along the water potential gradient evaporates at the end of the column where the solar radiation is absorbed. It is then recovered with a condensing cover. To examine the feasibility of this concept, simultaneous transportation of heat and moisture through the sand column from varying depths of water table under constant irradiance was examined. A mathematical model, based on Philip and de Vries (1957), predicted that the rate of evaporation from a uniform sand column is maximum when the water table is 0.1 m deep. This is because the water potential decreases with height from the water table, whereas the temperature increases with height. Experimental results partially supported such a prediction. The results also suggested that the evaporation rates from the surface of the sand column were slightly higher than that from the water table. Thus, the proposed method could be useful if a proper porous material is selected.View full abstractDownload PDF (771K) -
Koji TAMAI, Yuji KOMINAMI, Takafumi MIYAMA, Yoshiaki GOTO, Yoshikazu O ...2008 Volume 64 Issue 4 Pages 215-222
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESSWe monitored soil respiration at a valley bottom and a ridge above that valley in an experimental forest and quantitatively estimated the effect of topography on soil respiration. Compared to the valley bottom, the ridge showed a lower rate of soil respiration in summer and a higher rate in winter; the seasonal difference was caused by soil drying in summer and soil warmth in winter. Both the valley bottom and ridge had annual soil respiration rates of approximately 6.2 tC ha-1 year-1. However, the annual value for the ridge included the estimated respiration acceleration due to warm soil temperature (0.68 tC ha-1 year-1) and deceleration caused by soil drying (0.62 tC ha-1 year-1).View full abstractDownload PDF (955K) -
Hiroki OUE, Shingo MOTOHIRO, Kenta INADA, Akira MIYATA, Masayoshi MANO ...2008 Volume 64 Issue 4 Pages 223-232
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
Advance online publication: October 10, 2008JOURNAL FREE ACCESSThe stomatal conductance (gs) of rice leaves in vertical canopy layers was measured in both the ambient and FACE fields, where the concentration of ozone ([O3]) was elevated artificially, during the heading and flowering stages, 2007. The gs sub-model of rice was developed by a multiplicative approach with modifications of PAR, VPD, AOT40 and [O3], while the multi-layer model of the O3 uptake process in the rice canopy was developed by incorporating the gs sub-model.
By the proposed model, vertical profiles of O3 fluxes on a single leaf (FO3) and in each canopy layer were calculated in the conditions 46.0, 40.2 and 43.6 ppb of [O3] at z = 280 cm at 1030, 1200 and 1530 h on August 30. O3 uptake by a single leaf (-FO3) in the upper canopy layer peaked at 1530 h and was smallest at 1200 h. The smallest -FO3 at 1200 h was caused not only by the lowest [O3] but also smaller gs, while the smaller gs at 1200 h was caused by smaller PAR on the flag leaf, even under the largest global solar radiation (SR) condition, because the leaf stands erect. The estimated O3 uptakes in the paddy field were 14.9, 13.7 and 12.1 (nmol m-2 s-1) at 1030, 1200 and 1530 h, respectively.
The predicted FO3 under different [O3] conditions by the model revealed that FO3 would exceed the threshold of -6 nmol m-2 s-1 in more than 60 ppb [O3] at 1030 and 1200 h and in more than 50 ppb at 1530 h. The predicted FO3 under different SR conditions with fixed [O3] of 80 ppb revealed that FO3 would reach the threshold in more than 400 W m-2 of SR at 1030 and 1200 h and more than 200 W m-2 at 1530 h under this relatively high [O3] condition.View full abstractDownload PDF (1195K) -
Takahiro HAMASAKI, Ryoji SAMESHIMA, Tomoyoshi HIROTA2008 Volume 64 Issue 4 Pages 233-242
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
Advance online publication: August 31, 2008JOURNAL FREE ACCESSWe evaluated the effects of delayed emergence of soybean caused by drought and soil crust on soybean growth (development from emergence to flowering and yield per plant). We carried out a field experiment (soil crust simulated with wooden boards) and a pot experiment (with actual soil crust). Soybean cultivars Toyomusume, Tsurumusume, and Yukihomare were sown on a conventional sowing date in control plots, dry soil plots, and soil crust plots and 13 or 14 days later in a late-sown plot. Delayed emergence due to drought shortened the period from emergence to flowering, or had the same effect on the flowering date as late sowing. Delayed emergence by up to 11 days due to soil crust resulted in earlier flowering compared to plants delayed by late sowing. These results mean that in cases where late flowering is expected because of delayed emergence caused by drought or soil crust, resowing would not restore the earlier flowering date.View full abstractDownload PDF (766K) -
Hidetoshi INADA, Masahiro YAMAGUCHI, Ryohei SATOH, Daiki HOSHINO, Aki ...2008 Volume 64 Issue 4 Pages 243-255
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
Advance online publication: September 30, 2008JOURNAL FREE ACCESSThe chronic effects of ambient levels of O3 on photosynthetic components and radical scavenging system of leaves at different positions on the main stem of Japanese rice (Oryza sativa L.) were investigated. Two cultivars of Japanese rice (Koshihikari and Kinuhikari) were planted in plastic boxes filled with flooded Andisol in 9 chambers on 15 May, and exposed daily to charcoal-filtered air or O3 at 60 or 100 nl l-1 (ppb) (10:00-17:00) from 30 May to 20 September 2007.
The activity and concentration of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the leaves of both cultivars were not significantly affected by exposure to O3. However, the concentrations of chlorophyll in the lower leaves on the main stem of both cultivars were significantly reduced by the exposure to 100 ppb O3, while the exposure to O3 significantly increased the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR); regardless of the leaf position in the two cultivars. Although no significant combined effect of O3 and cultivar on the concentration of chlorophyll, the activity and concentration of Rubisco, or the concentration of antioxidants and activity of radical scavenging enzymes was observed, there was a highly positive correlation between the AOT40 (accumulated exposure over a threshold of 40 ppb) of O3 and the relative activity of APX, MDAR or GR in leaves exposed to O3 to that in leaves exposed to charcoal-filtered air of both cultivars. These results suggest that APX, MDAR and GR played important roles in the antioxidative response of Japanese rice to O3. However, the detoxification capacity of reactive oxygen species by APX, MDAR and GR was insufficient to prevent the adverse effects of ambient levels of O3 on the concentration of chlorophyll in the two cultivars of Japanese rice.View full abstractDownload PDF (813K)
Full Papers (in Japanese)
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Naru TAKAYAMA, Haruhiko YAMAMOTO, Kiyoshi IWAYA, Wang FEI, Yoko HARADA ...2008 Volume 64 Issue 4 Pages 257-270
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESSThe actual condition of occurrence of heat island and the cooling effect to heat stress in the central urban area by the large roof greening building (ACROS Fukuoka) were investigated in Fukuoka city area which is the largest city of Kyushu region. The operative temperature which is the heat energy that a human body receives from the surrounding environment by heat conduction and radiation was calculated by using meteorology data acquired on the city area in summer at 2007. The heat stress index (HSI) was defined a human body temperature that a standard adult man had to cool by perspiration when he was standing during 10 minute as index of heat stress in the city area.
A decreasing effect for operative temperature by sun shade of typical urban tree Zelkova was estimated from 5.7 to 7.2 degree-C. The operative temperature would be increased 4.10 degree-C and 0.64 degree-C, respectively, if the air temperature or the ground surface temperature was 5 degree-C higher under the weather condition of August-1 2007 at the roof floor of ACROS Fukuoka. A breeze, however, has an operative temperature decreased remarkably, so the heat stress would be eased. The HSI would reduce 0.26 and 0.14 degree-C, respectively, under sun light or sun shade condition, if the wind speed is 5.4 ms-1.
As a result of a comparison of a ratio of radiation energy input to increased air temperature from early morning to noon, it was estimated that an increasing air temperature on ACROS greening garden was reduced about 70%-73% of the central urban area. The operative temperature and HSI would be risen about 4.2%-6.9% and 7.6%-11.8%, respectively, if the building is a non-greening building, we concluded.View full abstractDownload PDF (1677K) -
Tomoyoshi HIROTA, Masuo HASEGAWA, Hiroyasu TANAKA, Shinji SUZUKI, Tosh ...2008 Volume 64 Issue 4 Pages 271-279
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESSIn snow-covering region of Japan, the promotion of snowmelting with application of agricultural snowmelting agents (“Yusetsuzai” in Japanese) has been widely carried out by farmers at the snowmelting season. When black colored materials with albedo-lowering effect are spread on snow surface, absorption of solar radiation by snow is increased, the snowmelting is promoted and snow thawing date becomes earlier. As a result, the growing season of crop plants is extended. Existing agricultural snowmelting agents have been mostly made from industrial waste materials or industrial processed products due to requirement for the low cost of the raw materials. These agents may contain harmful heavy metal elements and may lead to environmental pollution. To solve these problems, we developed the new agricultural snowmelting agents made from recycled bio-waste materials generated from the fields of agriculture and fishery. The developed snowmelting agents were made from shells of Patinopecten yessoensis, fowl droppings and processed wastes of fish and shellfish, etc. Especially, the shells of Patinopecten yessoensis has problems due to generation of a huge quantity in Hokkaido. Therefore, the recycling-use of these waste materials was strongly requested and expected. The developed snowmelting agents were possible to spread efficiently and safely on the snow-surface without wide scattering by controlling the particle size within the range larger than 100 μm and smaller than 1180 μm. Results obtained from the field experiment showed that the albedo was decreased from 0.70 for natural snow to 0.20 and the promotion of snowmelting for 11 days was recognized when 100 kg 10a-1 of developed agent was spread. The promoting ability of the developed agent was equivalent to those of the existing commercial snowmelting agents.View full abstractDownload PDF (917K) -
Yui NAGATANI, Kiyoshi UMEKI, Tsuyoshi HONJO, Hirofumi SUGAWARA, Kenich ...2008 Volume 64 Issue 4 Pages 281-288
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
Advance online publication: October 01, 2008JOURNAL FREE ACCESSThe cooling effect of urban green area on the surrounding area has been studied by many researches. Some studies observed seeping-out phenomenon or park breeze where the cooled air in the park flows outward to all direction of urban area. But there have been few studies on the movement of cooled air inside the urban green area when of seeping out phenomenon occur. In this study, we analyzed the movement of cooled air inside the urban green area at calm night and the relation with the seeping out phenomenon. Measurements were done during 23rd, 26th and 27th, July 2002 in Shinjuku-Gyoen Park. Thermocouples were set in 200 m lines with the interval of 20 m. We called these thermocouples as thermocouple array and three thermocouple arrays were set in the park. Two supersonic anemometers were used to measure wind velocity at the north and south edge of the park to detect the seeping out flow. In the analysis, the movement of cooled air was calculated by using cross correlation between pattern where temperatures decrease more than 1 K in 10seconds during 120seconds. We chose the points that indicated high cross correlation value more than 0.75 to calculate the velocity of cooled air. Most of velocities of the movement were between 0.1 m/s and 0.2 m/s at all points. At the south part of the park, the movement was measured most frequently. Velocity of the cooled air movement was smaller than the wind velocity measured by supersonic anemometers. Cooled air movements were not observed when the wind velocity was more than 1 m/s.View full abstractDownload PDF (1557K)
Short Papers
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Seiji SHIMODA2008 Volume 64 Issue 4 Pages 289-293
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESSThe aim of this study was to investigate the cessation of cultivation act as a sink or source for belowground carbon pools in former paddy fields. We measured soil carbon content and stable carbon isotopic ratio (δ13C) in three abandoned agricultural fields in Higashi-Hiroshima, Japan. The fields were located within 0.20 km of one another and had been abandoned for 2, 5, or 10 years (2Y, 5Y, 10Y fields). The cessation of cultivation of agricultural fields was dominated by C4 photosynthetic type grass. The return of carbon in grass litters to the soil caused the soil δ13C to increase after abandoned; thus, the soil δ13C value was lowest in the 2Y field (-24.2‰) and highest in the 10Y field (-22.1‰). While the large root biomass in fields after the long-term cessation of cultivation is a potential source of carbon input into the soil, soil carbon content was lower in the fields abandoned for longer. Land use change (from paddy to upland grasses) may lead to a decrease in the soil carbon content in the fields after abandonment in this area.View full abstractDownload PDF (617K) -
Yohei HAMADA, Takehisa OIKAWA2008 Volume 64 Issue 4 Pages 295-300
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
Advance online publication: September 30, 2008JOURNAL FREE ACCESSThe soil air samplers used in previous studies were mainly designed to collect soil gases at only a single depth. In this study, we developed a simplified multilevel sampler for extracting soil air at several depths with a single probe. Its applicability was investigated by comparison with a single-level sampler previously used and by the theoretical and practical evaluation of the reliability of the measured profiles of carbon dioxide in soil air under natural soil conditions. The profiles of carbon dioxide obtained with both types of samplers were basically the same, while the homogeneity of the extracted soil air was verified by a continuously duplicated half-volume extraction. The knotted structure of the multilevel sampler apparently controlled preferential airflow along the sampler shaft without the use of any filling substances, while the spherical distributions of the extracted soil air, which were simply evaluated from the air-filled porosity and did not overlap with each other, theoretically supported the reliability of the measured profiles. The multilevel soil air sampling provides for the installation of fewer samplers, less soil disturbance, and provides more accurate soil gas profiles compared to the previous methods.View full abstractDownload PDF (737K) -
Yukiyoshi IWATA, Masaki HAYASHI, Tomoyoshi HIROTA2008 Volume 64 Issue 4 Pages 301-309
Published: March 10, 2008
Released on J-STAGE: March 16, 2009
JOURNAL FREE ACCESSSnow cover insulates the soil surface from cold air in winter, thereby influencing the transfer of heat and water, and the freeze-thaw processes. To evaluate the effect of snow cover on land-atmosphere energy exchange, a field study was conducted in Hokkaido, Japan. The soil froze to a depth of 20 cm in early December while the snow cover was relatively thin. The soil then started thawing from the bottom of the frozen layer after the snow cover reached a thickness of 70 cm in January. The thawing was induced by a dramatic reduction in the heat flux from the soil surface to the snow, while the upward flux from the deep (>1 m) soil zone provided a steady supply of heat. The magnitude of heat flux in the deep soil zone is normally much smaller than the flux in the near-surface soil exposed to large fluctuations of air temperature. However, when the soil surface was insulated by snow, the magnitude of the near-surface heat flux decreased and became comparable to that of the flux in the deeper soil zone, indicating that the effects of the latter increased after the insulation of the soil surface. Since heat flux is sensitive to thermal conductivity, accurate estimation of the thermal conductivities of soil and snow is critical for a quantitative understanding of the freeze-thaw processes.View full abstractDownload PDF (778K)
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