Hydrometer is used in soil analysis to determine

Correct option is D

The correct answer is (D) Soil texture

Explanation:
• Soil texture refers to the relative proportions of sand, silt, and clay particles in the soil.
• The Hydrometer method is a common laboratory procedure for mechanical analysis (particle size analysis).
• It is based on Stokes' Law, which states that larger particles settle faster than smaller particles in a liquid suspension.
• A soil-water suspension is created using a dispersing agent (like sodium hexametaphosphate). The hydrometer measures the density of the suspension at specific time intervals. As particles settle, the density decreases, allowing the calculation of the percentage of sand, silt, and clay.

Information Booster:
• The Bouyoucos hydrometer is the specific type most commonly used in soil science.
• Sand particles settle within about 40 seconds, while silt particles take about 2 hours, leaving only clay in the suspension.
• Soil texture is a permanent property of the soil and does not change easily with management.

Additional Knowledge:
• Soil moisture (Option A) is determined using gravimetric methods, Tensiometers, or Neutron probes.
• Hydraulic conductivity (Option B) is measured using constant head or falling head permeameters.
• Soil structure (Option C) is usually assessed through field observation of peds or dry/wet sieving for aggregate stability.