Gujarat BoardEnglish MediumSTD 9ScienceNatural Resources3 Marks
Question
What is the composition of red soil?
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Answer
Red soil is rich in iron oxide, but deficient in nitrogen and lime. Its chemical composition generally includes non-soluble material $90.47 \%$, iron $3.61 \%$, aluminium $2.92 \%$, organic matter $1.01 \%$, Magnesium $0.70 \%$, lime $0.56 \%$, carbon di-oxide $0.30 \%$, potash $0.24 \%$, soda $0.12 \%$, phosphorus $0.09 \%$ and nitrogen $0.08\ %$. Its colour is mainly due to ferric oxides occurring as thin coatings on the soil particles while the iron oxide occurs as haematite or as hydrous ferric oxide, the colour is red and when it occurs in the hydrate form as limonite the soil gets a yellow colour. Ordinarily the surface soils are red while the horizon below gets yellowish colour.
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