加纳阿善堤地区农户参与稻田项目的决定因素研究

本文对加纳阿哈福阿诺南区（Ahafo Ano Southdistrict）农户参与稻田项目的决定因素进行研究。稻田项目的实施，主要基于加纳稻米消费的扩张，导致了对生产自给的需求。为此，日本的一些机构在加纳的较低洼地区引入了稻米的生产。当然，在参与稻田项目的全部三阶段（1997—2001，2002—2004和2004—2009）的农户中，也存在着不同的问题。因此，在前两个阶段结束和第三个阶段接近完成的情况下，研究农户参与稻田项目的决定因素，从而促进项目逐步完善就显得尤为重要。由于稻田开发项目主要集中在阿哈福阿诺南区，这一地区分布有主要的流域，因此，本研究也主要在此地区进行。受访者主要从5个村庄中随机抽取，这5个村庄涵盖了项目的所有3个阶段，共选取了225名农民，通过结构式问卷调查方式搜集了相关资料。论文运用描述性统计方法分析了样本农民的社会经济特点，同时运用Probit模型对影响农户参与稻田项目的决定因素进行了研究。结果表明，样本中多数农民为50岁以下男性，他们具有较高的教育水平，同时信奉基督教，但他们在低地种植水稻的经验不到5年，水稻种植面积不到5英亩，约有61％的接受访问者每户有5至10人，样本中参与项目的人数少于没有参加项目的人数。从Probit模型的结果来看，确定模型拟合度的卡方值在1％的统计水平上显著，“参与稻田项目的持续性”（t=5．02）和“村庄稻田项目的起始时间”（t=-1．53）两变量分别在5％和10％的统计水平上显著。从文中也可以看出，在引进稻田项目的同时，也引进了适当的田间管理和水资源管理。为了确保农民参与稻田项目的可持续发展，也有必要对论文中基于项目3阶段分析所揭示的重要的社会变量给予政策上的重视。

Soil Development and Fertility Characteristics of Inland Valleys in the Rain Forest Zone of Nigeria: Mineralogical Composition and Particle-Size Distribution

The particle-size distribution and mineralogical composition of the clay （〈 2 μm） and fine-sand （0.25-0.10 mm） fractions in soils of two inland valleys in Abakaliki and Bende, Southeast Nigeria, were investigated to provide basic information on soil-forming processes and agricultural potentials. These soils were silty or clayey, deriving from Cretaceous or Tertiary shale materials. The particle-size distribution and its computation on a clay-free basis revealed relatively remarkable lithologic breaks in a couple of pedons. The effect of lithologic discontinuities on soil mineralogical composition was not, however, conspicuous. Petrographic investigation revealed that quartz predominantly comprised the fine-sand fraction in the soils at both study sites. Nevertheless, the clay mineralogical composition of the soils was a mixture of kaolinite, irregularly interstratified smectite-illite intergrades （S/I）, hydroxyl-A1 interlayered 2：1 type clays （HICs）, vermiculite, smectite, halloysite and illite along with fine-sized quartz in Abakaliki. The soils of Bende predominantly contained smectite, which was partially interlayered with hydroxyl-A1 and kaolinite. It is suggested that seasonal floodwater has slowed the disintegration of weatherable clay minerals inherited from the shale, while quartz originating from the sandstone is predominant in the fine-sand fraction. Additionally, a possible soil-forming process observed at the both study sites was ferrolysis, which was indicated by a clear decreasing pattern of HICs downward in the soil profiles, The entry of S/I and vertical distribution patterns for a couple of clay minerals in the pedon suggested that the soils in Abakaliki have developed under the significant influence of aeolian dust delivered by the Harmattan. The findings might describe a site-specific deposition pattern of Harmattan dusts as well as hydromorphic soil-forming processes in the wetlands of the inland valleys.

Tectonics of South China Continent and its implications

This paper aims at exploring the tectonic characteristics of the South China Continent （SCC） and extracting the universal tec- tonic rules from these characteristics,to help enrich the plate tectonic theory and better understand the continental dynamic system. For this purpose, here we conduct a multi-disciplinary investigation and combine it with the previous studies to reas- sess the tectonics and evolution of SCC and propose that the tectonic framework of the continent comprises two blocks, three types of tectonic units, four deformation systems, and four evolutionary stages with distinctive mechanism and tectonic characteris- tics since the Neoproterozoic. The four evolutionary stages are： （1） The amalgamation and break-up of the Neoproterozoic plates, typically the intracontinental rifting. （2） The early Paleozoic and Mesozoic intracontinental orogeny confined by plate tectonics, forming two composite tectonic domains. （3） The parallel operation of the Yangtze cratonization and intracontinental orogeny, and multi-phase reactivation of the Yangtze craton. （4） The association and differentiation evolution of plate tectonics and intraconti- nental tectonics, and the dynamic characteristics under the Meso-Cenozoic modem global plate tectonic regime.