I Read That Red Soil Is Acidic In Nature. But I Know That Red Soil Contains Iron Oxide Which Imparts It Red Color

But Iron Oxide Is Basic In Nature As It Is An Oxide Of A Metal.

So My Question Is What Other Materials Are Present That Make It Acidic

Please Help On 29th NSO Is There

Dear Student

Yes, you are correct that red soil get its unique red tint due to the presence of iron oxide deposits in it. Red soil is only slightly acidic. The soil is acidic because of the following reasons:

• Red soil is formed by weathering of acid crystalline rocks.
• The content of essential nutrients like nitrogen, phosphorus and lime is very less in red soils which results in its slightly acidic behaviour.
• Acidity in soils also comes from H⁺ and Al³⁺ ions in the soil solution and absorbed to soil surfaces. Al³⁺ is important in acid soils because Al³⁺ reacts with water (H₂O) releasing extra H⁺ ions and these H⁺ ions result in acidic nature of soil. 
• Many other processes like rainfall, fertilizers, acid rain etc. contribute in making the soils acidic.