Are sandy soils infertile? -Revisiting soil fertility-

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To challenge our common sense that sandy soils are infertile, I have compared the sandy soils in Niger and Namibia and conducted the field trial in Niger. I found that the soils both in Niger and Namibia contain almost same amount of sands, while the ratio of clay to silt was higher in the soils in Namibia than those in Niger. In addition, clay minerals are also different between soils in Niger and Namibia, possibly reflecting the difference in soil formation processes. The field trial in Niger revealed that soils with more than 5% of silt and clay tended to form crust in soil surface. Soil crust retarded water infiltration into soil, which reduced the available water for plants. Finally, due to less available water in the soil, plant growth was seriously damaged.