ブラジルの草地と土壤
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概要
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The sample of the analysed soils were broadly collected from 6 states of the country, including 90 top soils and sub-soils from 44 sites. We studied on the physical and chemical properties such as color, constitution, structure, stickness, pH, exchangeable acidity, nitrogen, humus, carbonnitrogen ratio, ion exchange capacity, exchangeable CaO, MgO, available phosphoric acid and mechanical analysis, according these soils. The most of soils were collected from state of S<ao>^^^∿ Paulo and Parana (see Fig. 1). Then it was expected that the present data would be utilized as consultation materials of cultivation for the Japanese and the Brazilian farmer in this country, because about 90% of Japanese emigrants have deposited and undertaken their economical lives in these states. Fig. 2 shown the map of great soil group in state of S<ao>^^^∿ Paulo issued by Campinas Agricultural Institution. The description of each sampling site was shown in each paragraphs. On the analytical data for observations of the soil profile, the following conclusions could be drown in general, though the soil reaction were more variation from area to area (in range of 4.68-7.75 at top soil and 4.04-7.64 at subsoil). The samples shown that its pH over 7 were 3 sites and pH over 6 were 19 in total 44 sites. In Japanese grassland, the range of pH is 4.0-5.5 mainly. The content of exchangeable bases in Brazilian soils was higher than of Japanese grassland. However, total nitrogen and humus content were conspicuous low compared with the case of Japan. It was considerd the characters of tropical and subtropical soils. The most of carbon-nitrogen ratio were within a moderate or a low value. In general, "Terra Roxa Mista" comprised more sands its cation-exchange capacity was low. The amount of available phosphoric acid was poor, particularly, in grassland such as "Campo Cerrado" or "Campo Limpo" In a sort, the soils in Brazilian grassland were extremely poor in available plant nutrients, and it was considered the grazing capacity per unit area to support at high level was difficult, although in another way they have such favorable features as weak acidity and high exchangeable bases contents comparing to the case of Japan. In the soils of Brazilian grassland, the dressing of nitrogen seemed to be the key for improving grassland. By such control of the dominated grass family, the productivity per unit area could raise its level. In the case strong acidic soils, when phosphatic fertilizer was dressed to the soil, the fixation of phosphate occured in this condition, for the concentration of Al was too high. On the other hand, when pH of soils was high, the fixation of phosphate would occur in this condition, for phosphate would combine calcium. Accordingly, at the time of dressing of phosphate, it was considered that the close attention to paid. Author wishes to thank Dr. H. Saeki, President of Hyogo Agricultural College and Ph. Dr. T. Shimizu for their stimulating discussion of the present report and review of the manuscript and offer of many useful suggestions.
- 神戸大学の論文