Journal of the Japanese Agricultural Systems Society
Online ISSN : 2189-0560
Print ISSN : 0913-7548
ISSN-L : 0913-7548
Volume 32 , Issue 2
Showing 1-3 articles out of 3 articles from the selected issue
Contributed paper
  • Akira SETOGUCHI, Kazato OISHI, Hisaya SAKAI, Hideyo KITAURA, Hajime ...
    2016 Volume 32 Issue 2 Pages 57-69
    Published: April 30, 2016
    Released: October 31, 2016

    The objectives of this study were to evaluate the environmental and economic impacts of year-round-grazing systems and a conventional housing system for Japanese Brown fattening steers by the life cycle assessment (LCA) method. Four treatments were designed in this study; grazing fattening without feed rice (G group), grazing fattening with feed rice (GR-1 and GR-2 groups) and conventional housing fattening (H group). For the three grazing groups (G, GR-1, GR-2), supplemental concentrate was constantly supplied and hay was supplied only in winter. The emissions from feed production, feed transportation, animal management, manure treatment and ruminal fermentation were assessed for the LCA. Impacts categories considered were energy consumption, global warming, acidification, and eutrophication. Impacts of NO3 and P emissions from fertilizer and manure on eutrophication were included. The functional unit was set to be 1 kg of average daily gain. The impact of carbon sequestration from pasture was also considered. The result showed that environmental impacts of G group on global warming, acidification, and eutrophication were significantly higher than those of H group (P<0.05). Considering carbon sequestration in the pasture, the sensitivity analysis indicated that grazing systems could reduce substantive impact on global warming. For economic assessment, annual carcass sales of G group were significantly lower than those of H group (P<0.05) and annual production costs showed no significant difference among groups.

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Technical Paper
  • Masako MIYASHITA, Yasuhiko MURAMATSU, Tomoyuki KAWASHIMA
    2016 Volume 32 Issue 2 Pages 71-80
    Published: April 30, 2016
    Released: October 31, 2016

    Alternate Wetting and Drying (AWD) is a water-saving technology that is also capable of mitigating Greenhouse Gas (GHG) emission from paddy fields; and thus expected to be diffused over a larger area. In Vietnam, the An Giang province is known as a region where the AWD technology has been widely applied and practiced. Assessment and analysis of key drivers and constraints behind the rapid and wide application of the technology in the region would pave the way for fighting against global warming and water shortage. This paper presented and discussed a brief historical background, water management and challenges based on a field study that has combined an interview of pertinent government officers and focus group discussions of farmers. Key findings of the study included that the farmers did not adopt water level management by exercising objective judgment with a simple measuring devise to gauge ground water level. On the other hand, the farmers adopted and modified it in more practical manner by exercising empirical judgment on water stress of plant growth and conditions of surface soil (AWD of farmers). The main incentive for the farmers to adopt AWD of farmers is that introduction of the technology reduced pump operation cost, however it was recognized that the beneficiaries were limited to pump owners under the current contract conditions. Proper design of contract conditions to ensure equitable distribution of benefit among farmers is expected to accelerate diffusion process of the technology. Site conditions differ significantly among farm plots, which may have prevented a standardized or uniform approach. In addition to the diffusion of the AWD technology as a technical package containing provision of quality seeds, mechanization under a strategic extension campaign, fundamental government approaches are important, mobilization of notable farmers who are trusted by other villagers, selection of demonstration farms that is easily accessible and group formation of neighboring farmers. To be capable of mitigation GHG emission from paddy fields over a larger area, it is efficient that the project combined the introduction of new agricultural technology and low-interest loan is implemented with the utilization of the Joint Crediting Mechanism in the case that farmers exercise with a simple measuring devise to gauge ground water level and the independent organization asset and recognize it appropriate. An assessment of social acceptability of modifying contract condition of pump leasing and duplication of the government approach to AWD diffusion are necessary.

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  • - An automatic field camera system for capturing runoff velocity and preliminary case studies -
    Kojiro YUTAKA, Michio SHIBAYAMA, Eiji KANDA, Sunao ITAHASHI, Kenji ...
    2016 Volume 32 Issue 2 Pages 81-89
    Published: April 30, 2016
    Released: October 31, 2016

    In recent years, the increased incidence of sudden heavy rains in Japan has enhanced the occurrences of surface runoff from sloping farmlands. These runoff events negatively affect the ecosystems as a result of the fertilizer components or heavy metals present in the runoff water that flows into local watersheds. A conventional method for measuring the extent of surface runoff has been to use water-level meters installed at the bottom edge of sloping farmlands. However, such equipment may provide unreliable data because of, for instance, pileup of crop residues and/or soil particles around the sensor. To avoid such a problem, this study proposes a sensing system that uses automatically captured moving images of surface runoff. The system was tested in outdoor artificial sloping fields for more than a year in total. Several sets of images, recorded actual rainfall levels and runoff amounts, were obtained during natural rainfall/runoff events in Ibaraki and Kagoshima prefectures. Particle image velocimetry (PIV) was applied to the captured moving images to estimate the runoff velocities utilizing floating tiny residues as markers of water flow, which are essential for the PIV procedure. The estimated values of runoff velocity reasonably corresponded to the instantaneous rainfall levels and runoff amounts and were relatively close to the velocity measurements obtained using alternative methods.

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