Question

The recommended permissible gap between two tiles in tile drainage of silt loam soil and silty clay loam soil is

• A. 1 mm to 3 mm
• B. 3 mm to 5 mm
• C. 5 mm to 7 mm
• D. 7 mm to 9 mm

Hint:

Tile drain joint gaps: Silt loam silty clay loam $= 3\text{--}5\text{ mm}$. Sandy/loose soils $= 1\text{--}3\text{ mm}$ (with filter envelope).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Subsurface agricultural tile drainage relies on open unsealed joints between individual clay/concrete pipes to permit water entry while preventing soil piping and sediment entry.

Step 2: Detailed Explanation:
In subsurface tile drainage systems using clay or concrete drain tiles:
- For fine-textured, cohesive soils like silt loam and silty clay loam, the standard recommended joint spacing gap is \(3\text{ mm to } 5\text{ mm}\) (\(1/8\text{ to } 3/16\text{ inch}\)).
- For sandy and non-cohesive soils, smaller gaps of \(1\text{ mm to } 3\text{ mm}\) (along with gravel/synthetic envelopes) are maintained to prevent sand ingress and siltation.

Step 3: Final Answer:
Hence, the recommended permissible gap is 3 mm to 5 mm, corresponding to option (B).