Which of the following statement is/are correct with reference to bulk density? (A) Bulk density of soil depends on texture, structure, and organic matter. (B) Bulk density decreases with addition of organic matter to the soil. (C) Fine-textured soils have more bulk density than coarse-textured soil. (D) Compaction of soil increases the bulk density.

Correct option is A

The correct answer is (A) (A), (B), and (D) only

Explanation:
• Statement (A) is correct: Bulk density is influenced by the soil's physical makeup, including how much pore space exists (structure) and the weight of the solids (texture and organic matter).
• Statement (B) is correct: Organic matter is very light and promotes soil aggregation (more pore space), so adding it significantly lowers the overall bulk density.
• Statement (C) is incorrect: Generally, coarse-textured soils (sandy) have higher bulk density than fine-textured soils (clay). This is because clay soils have high total porosity and better structure, whereas sandy soils have less total pore space despite having larger individual pores.
• Statement (D) is correct: Compaction squeezes soil particles together, reducing pore space (especially macropores) and therefore increasing the mass per unit volume (bulk density).

Information Booster:
• Typical bulk density values: Sandy soils (1.4 – 1.8 g/cm³), Clay soils (1.1 – 1.4 g/cm³).
• Particle density is generally constant around 2.65 g/cm³; it is the pore space that determines variations in bulk density.

Additional Knowledge:
• Bulk density is calculated as: $BD = \frac{Weight \, of \, oven \, dry \, soil}{Volume \, of \, bulk \, soil}$.
• High bulk density can restrict root growth and reduce water infiltration.