Study on external economy on terraced paddy fields : economic and soil scientific approach

梯田外部经济研究:经济与土壤科学方法

• 批准号: 08660272
• 负责人: IIGUNI Yoshiaki
• 金额: $ 1.54万
• 依托单位: KOCHI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08660272/
• 关键词: Terraced paddy fields; External economy; Land use; Siba grass; Low molecular weight organic acids; Soil microorganisms; Soil hardness; 芝草地

This study is separated into two parts. One is economic analysis and the other is soil scientific analysis. In the former analysis, we firstly studied the current situation of terraced paddy fields in Ohtoyo-cho of Kochi prefecture. With the data of geographical and geological survey, we identified that the paddy fields stand on the landslide area. Until now the function of dam of paddy fielda is stressed as a basis for supporting the fielda. It is, however, not appropriate in this area. The space-creation function is more important. Additionally we sent out questionnaires to inhabitants in Ohtoyo-cho and Tokushima-shi, which locates on the downstream of Yoshino river and is connected to Ohtoyo-cho by the river. With the questionnaires we clarified the difference of recognition between the inhabitants and estimated the willingness to pay for maintaining the paddy field. Finally we discussed the optimal land use with using siba grass in that area. The major results of soil scientific analysis are fallowed : Monitoring of the local meteology, soil and water quality, soil microorganisms, low molecular weight organic acids in soils, under reclaimed siba (Sosiba japonica) grass land was carried out at Hanada Farm (Nahari-cho, Aki-gun, Kochi) and Saito Farm (Nankoku-shi, Kochi). Upon the utilization as siba grass land, water permeability became improved, because of the formation of root mat layr at the surface and hard-pan layr in the subsurface, and eventually, development of granular structure inbetween those two layrs. These changes in soil structure gave favorable changes for the stability of the ecosystem of reclaimed grass land in terms of the nutrient dynamics.

本研究分为两部分。一种是经济分析，另一种是土壤科学分析。在前一种分析中，我们首先研究了高知县大横町的梯田现状。根据地理地质调查资料，确定水田位于滑坡区。迄今为止，人们一直强调水田坝作为支撑水田的基础的作用。然而，这在这方面是不合适的。空间创造功能更为重要。此外，我们还向大横町和德岛市的居民发放了调查问卷，德岛市位于吉野河下游，与大横町相连。通过问卷调查，明确了居民对稻田维护的认知差异，并估算了稻田维护的支付意愿。最后讨论了该地区土地的最佳利用方式，即利用四叶草。土壤科学分析的主要结果如下：在高知县花田农场（Nahari-cho, Aki-gun，高知县）和斋藤农场（Nankoku-shi，高知县）进行了当地气象、土壤和水质、土壤微生物、土壤中低分子量有机酸的监测。利用泗坝草地后，地表形成根垫层，地下形成硬垫层，并最终形成颗粒状结构，透水性得到改善。这些土壤结构的变化在养分动态方面有利于复垦草地生态系统的稳定性。

项目成果

K.Iwasaki, Tsuji, M., and Sakurai, K.: "Fractionation of soil copper and manganese in the rhizosphere of finger millet." ibid. 501-502

K.Iwasaki、Tsuji, M. 和 Sakurai, K.：“小米根际土壤铜和锰的分馏”。

K.Sakurai et al: "Determination of low molecular weight organic acids in forest soils." T.Ando et al,Plant nutrition,Kluwer Academic Publisher. 503-504 (1997)

K.Sakurai 等人：“森林土壤中低分子量有机酸的测定”。