Match the following:

Set A	Set B
[i] In situ measurement	[a] Soil moisture
[ii] USDA	[b] Textural classification chart
[iii] Wilting range	[c] Above 15 bar
[iv] Arrangement of soil particles	[d] Soil structure

Correct option is A

The correct answer is (A) i-a, ii-b, iii-c, iv-d

Explanation:
• In situ measurement (i-a): This refers to measuring properties directly in the field. Soil moisture is commonly measured in situ using Tensiometers, TDR probes, or Neutron probes.
• USDA (ii-b): The United States Department of Agriculture developed the widely used Textural Classification Chart (Soil Texture Triangle) to determine soil classes based on the percentage of sand, silt, and clay.
• Wilting range (iii-c): The Permanent Wilting Point (PWP) is generally reached when soil moisture tension reaches $15 bars$. The range beyond this where plants cannot extract enough water to survive is the wilting range.
• Arrangement of soil particles (iv-d): This is the literal definition of Soil Structure. It refers to how individual soil particles (sand, silt, clay) are grouped into larger aggregates or peds.

Information Booster:
• Soil texture is a permanent property, while soil structure can be modified by tillage and organic matter addition.
• Field Capacity is the soil moisture held at $1/3 bar$ tension.
• Available Water Capacity is the moisture held between Field Capacity and PWP.

Additional Knowledge:
• The USDA texture triangle recognizes $12$ main textural classes (e.g., Sandy Loam, Silty Clay, etc.).
• Poor soil structure (like massive or platy) restricts root growth and water infiltration, while granular structure is best for most crops.