Question

The alluvial soil is fertile because of the presence of ____________ in it.
A. Organic nutrient
B. Sand
C. Clay
D. Iron oxide

Answer 1

Hint: Alluvial soils are soils deposited by surface water. It will find them along rivers, in floodplains and deltas (like the Mississippi Delta), stream terraces, and areas called alluvial fans.

Complete answer:
Alluvial soil is one of the best soils, requiring the least water due to its high porosity.India is one of the richest countries in the world in terms of alluvial soil, which covers quite 46% of its total area of land. Now let’s see what makes alluvial soils fertile,

Alluvial soil is the most fertile soil because it has a loamy texture (contain sand, clay and slit) and is rich in humus, contains organic nutrients.
A granular material composed of finely divided rock and mineral particles are called sand. Sand with clay and slit helps to increase fertility of alluvial soil.
Clay soil is soil that's composed of very fine mineral particles and not much organic material. But clay is present in loamy texture which helps to increase fertility of alluvial soil.
Iron oxides are vital components in most soils as they have the main influence on chemical, physical, and microbial properties of soils.

Therefore the most appropriate answer for this question is A. Organic nutrients.

Note: Alluvial soils are widespread in the northern plains and the river valleys. These soils cover about 40 per cent of the entire area of the country. They are depositional soils, transported and deposited by rivers and streams. The alluvial soils vary in nature from sandy loam to clay. They are generally rich in potash but poor in phosphorus.