Customer soil

This refers to bringing into fields soil with the aim of improving soil quality, such as mountain soil with a high clay content and high iron and other nutrients, or muddy soil from lake bottoms, swamps, irrigation channels, etc., which is rich in organic matter, nitrogen, and other nutrients. Soil dressing has the effect of rejuvenating the soil by replenishing leached nutrients and increasing the thickness of the till. The method of irrigating cultivated land with the dressed soil suspended in water and allowing it to settle is called runoff dressing.

Since the enactment of the Law Concerning Prevention of Agricultural Land Soil Contamination (Law No. 139 of 1970), soil contaminated by cadmium and other substances has been improved by replacing it with uncontaminated soil, a method known as soil removal and soil replacement.

[Yuki Koyama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

土壌の性質を改善する目的で、粘土含量が高く鉄その他の養分の多い山土や、有機物、窒素などの養分に富む湖底や沼、用水路などの泥土を田畑に搬入することをいう。客土は、溶脱した養分を補給して土壌を若返らせ、また、作土の厚さを増やす効果がある。客入土を水に懸濁させて耕地に灌漑(かんがい)し、沈殿させる方法を流水客土とよぶ。

　農用地の土壌の汚染防止等に関する法律（昭和45年法律第139号）の制定以降、カドミウムなどで汚染された土壌を汚染されていない土壌と入れ替えて改良することが行われているが、このような方法を排土客土という。

［小山雄生］

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