Journal of the Japanese Agricultural Systems Society
Online ISSN : 2189-0560
Print ISSN : 0913-7548
ISSN-L : 0913-7548
Volume 28 , Issue 1
Showing 1-5 articles out of 5 articles from the selected issue
Contributed Paper
  • Soo Young PARK, Ippei HARADA, JongGeol PARK, Keitarou HARA, Chung-Sil ...
    2012 Volume 28 Issue 1 Pages 1-8
    Published: January 10, 2012
    Released: June 04, 2015
    JOURNALS FREE ACCESS
    This study aimed to estimate the methane emission from forest and cropland vegetation region by using WDCGG data, methane concentration, wind direction, wind speed, relative humidity and air temperature, from 1998 to 2007 on Minamitorishima, Yonagunijima and Ryori. We developed Greenhouse gas Emission Presumption Method (GEP Method) for presuming the methane concentration generated at the observation station. And this method was applied. As a result, The methane concentration was high in winter and low in summer on three sites. There was no difference of the methane concentration though day among morning, afternoon and nighttime. Annual average concentration in methane generation was 1820 ppb in onagunijima and 18 ppb was from sugarcane field. On the other hand, the annual average concentration was 1854 ppb in Ryori and 24 ppb was from forest vegetation region. Moreover, it was clarified that 70~80 percent of the amount of the methane emission was generated from vegetation region of forest and sugarcane field at the observation.
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  • Hiroyuki HIROOKA
    2012 Volume 28 Issue 1 Pages 9-17
    Published: January 10, 2012
    Released: June 04, 2015
    JOURNALS FREE ACCESS
    A dynamic simulation model for prediction on the transfer of radio-cesium, released after Fukushima accident, from feed into beef was developed. The model simulated radio-cesium concentrations in beef (muscle plus fat in carcass) and radio-cesium excretions with feces and urine from birth to slaughter. The model was used to examine the effects of radio-cesium contaminated situations in the calf period and various levels of radio-cesium concentrations in roughage during the feedlot period on radio-cesium concentration in beef and whole life excretion. The base situation was that average daily gain was 0.7 kg/day and slaughter weight was 700 kg. The two cases of transfer coefficients (the average value of 0.0385 and the upper value of 0.096) were assumed and the effect of a different management option (increased average daily gain during the feedlot period and smaller slaughter weight) was also investigated. The result showed that the predicted radio-cesium concentrations in beef at slaughter be below the maximum permitted level of radio-cesium concentration in beef (500 Bq/kg) under the regulation for radio-cesium content in feed by the Japanese government (5000 Bq/kg for a calf and 300 Bq/kg for a feedlot seer). The effect of contamination situation in the calf period on the concentration in beef at slaughter was negligible because of long feedlot period in Japan. It was however suggested that the case in extremely high radio-cesium concentration in roughage (more than 5000 Bq/kg) under the upper transfer coefficient may be above permitted level. Further, total radio-cesium excretion in whole life was remarkably large even under regulation level, indicating that considerable attention should be given when the excretion would be used as manure for crop production and fertilizer for gardening.
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  • Yuki OKAMOTO, Ueru TANAKA, Kei MIZUNO, Phi Nam NGUYEN, Van An LE
    2012 Volume 28 Issue 1 Pages 19-27
    Published: January 10, 2012
    Released: June 04, 2015
    JOURNALS FREE ACCESS
    This paper describes the changes of fishery environment focusing on the sediment by long-term monitoring in brackish lagoon area, central Vietnam. Acid-volatile-sulfide (AVS) and particle size distribution of sediment are measured at stated aquaculture period within 3 years. The AVS value of sediment became gradually high through the aquaculture season, which is the similar result as the previous report. However, after the aquaculture season experienced some flood events, reduction of the AVS value and the change of particle size distribution of sediment were found in several fishery sites. Also, some fishery sites where showed changes of particle size distribution of sediment through the year kept low AVS value. At some fishery sites faced environmental degradation that appeared as oxygen-deficient water. From the results, reduction of AVS value and the mechanism to keep low AVS value are proposed in 3 hypothetical models; [a] H2S gas solved out from sediment into water with no particle size distribution change, [b] changes of particle size distribution of sediment under the strong disrupting effect by flood, [c] changes of sediment by moderate disrupting effect through the year. These results suggest that some fishery areas possibly have a mechanism of sediment recovery to keep low AVS value through the changes of sediment via annual flood. On the other hand, there is concern about risk and effect on fishery production that several fishery sites observed high AVS value and oxygen-deficient water in middle season of aquaculture, and also some sites assumed as hypothetical model [a] of the AVS value reduction.
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  • A report of questionnaire survey in desertification area of Naiman Qi
    WUYUNNA, Katsuo OKAMOTO, Hiroyuki KAWASHIMA
    2012 Volume 28 Issue 1 Pages 29-45
    Published: January 10, 2012
    Released: June 04, 2015
    JOURNALS FREE ACCESS
    The questionnaire survey was conducted in the 3 villages (M, S and B) in Naiman Qi, Inner Mongolia Autonomous Region, China. These villages are located in Horqin Desert and have typical characteristics of the semiarid region. Information about the actual situation of inhabitants was collected by the questionnaire survey. On the basis of income, the inhabitants of each village were classified into 3 layers. The relationship between an income structure and an investment was analyzed. According to this analysis, advisable land use and farming-and-stockbreeding system were discussed. From a viewpoint of environmental economics, sustainable land use in desertificated region was also discussed. According to an income structure, stockbreeding was mainly carried on in M Village, farming mainly in B Village and a mixture of farming and stockbreeding in S Village. From a viewpoint of investment and income, in S Village, the income of stockbreeding was equivalent to the total income of agriculture and sideline and the investment in production was effective. This suggests that land productivity in the S Village is higher than that in other villages, and that management strategies, such as advisable land use and a mixture of farming and stockbreeding, of S villagers were more effective than those of other villagers. These also suggest that harmonizing a compound system of socioeconomic and nature is important for sustainable development in a semiarid region.
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Techinical Paper
  • Yasumaru HIRAI, Takahiro SUENAGA, Kunihiko HAMAGAMI
    2012 Volume 28 Issue 1 Pages 47-56
    Published: January 10, 2012
    Released: June 04, 2015
    JOURNALS FREE ACCESS
    The energy consumption and green house gas emissions associated with rice production in rice terraces were estimated by using the life cycle assessment (LCA) method. We conducted a survey on two farmers in Hoshino village, Fukuoka Prefecture, Japan. The energy consumptions for farmers A and B were 29,254 MJ/ha/Year and 29,637 MJ/ha/Year, respectively. The energy consumption due to fuel use accounted for the largest portion of the total energy consumption. We believe that the contributory factors are the inherent topographical disadvantages of rice terraces, which entail long hours of mowing in paddy levees and slopes and decrease the efficiency of machine operations. The surveyed farmer A has reduced his energy consumption by reducing fertilizer applications in accordance with the environmental conditions in mountainous areas. The carbon dioxide (CO2) emissions for farmers A and B were 1,980 kg/ha/Year and 1,998 kg/ha/Year, respectively, which are approximately identical to that previously reported. The nitrogen fertilizer application amount was low for farmer A and led to a reduction in the nitrous oxide (N2O) emission. The CO2 equivalent emissions of greenhouse gas for farmers A and B were 6,533 kg CO2/ha and 6,613 kg CO2/ha, respectively, which are approximately identical to that previously reported. The percentage compositions of methane (CH4), CO2 and N2O in the entire CO2 equivalent emissions were approximately 68%, 30%, and 1~2%, respectively. Our results corroborate the conclusions of previous reports that reductions in methane emissions are important.
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