ANALYTICAL STUDIES ON THE SOIL RELATED CHARACTERISTICS AT KOCHI-PREFECTURE

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The main results of the analysis are as follows.(a) Analysis About History and Current Situation of Farming: (1)Using the principal analysis and cluster analysis, we got six types of agricultural structure in the new division of cities, towns and villages and eight types of agricultural structure in old division. (2) Geological and soil feature are reflected in the agricultural types of the new division well. (3)Bad effect of heavy metal originated from greenstons on farming is observed in the central area at Kochi-prefecture. (4)Special attention is needed to create farming land which contains melange rocks.(b) Analysis of Zero Point of Charge (ZPC):Evaluation of ZPC was done using soil samples of eleven pedons from four regions,namely,Ohgata-cho,Taisho-cho,Yasu-cho,and Kagami-cho.ZPC and the magnitude of sigma_p were considered as good measures in relation to other phisico-chemical characteristics.New findings using the samples examined here are summarized as follows:(1)Even if the p … More ermanent charge clays are dominant as a charge source of soils,the magnitude of sigma_p increased with the amount of exchangeable aluminum,(2) furthermore,the contribution of the organic matter to lower the ZPC and to increase in the magnitude of sigma_p, which is normally recognized for strongly weathered soils,becomes less significant in the presence of permanent charge minerals in abundance.(3)the values of ZPC and sigma_p are regulative with each other,and (4) fertilization,especially lime amendment,makes ZPC value higher and sigma_p value larger.(c) Heavy Metal Distribution:The amount and form of heavy metals were examined in detail for the soils at Kagami and Yasu-cho,and the new findings are as follows.For kagami soils,(1)Anthropogenic cause,such as an application of agrochemicals including Cu,may increase the total Cu content,and (2)Fractionation study showed the difference in the form of Cu between the ones anthropogenically amended and originated from the parent materials. For Yasu soils,the 2C and 3C horizonds are strongly affected by the Cu and/or Fe mine itself.and (3) further increase in Cu content inevitably introduced by the irrigation water in situ may cause a damage to the crop production gradually through accumulation of Cu at the surface layer in the green house condition. Less