Question

Safe limits of land slope (%) for efficient irrigation in medium (loamy) soils is:

• A. 0.05 to 0.20
• B. 0.20 to 0.40
• C. 0.25 to 0.65
• D. 0.70 to 0.90

Hint:

Soils with lower infiltration (clay) require flat, gentle slopes (\(0.05\%\) to \(0.20\%\)).
Medium loamy soils fall in the middle range (\(0.20\%\) to \(0.40\%\)).
Sandy soils can support steeper slopes (\(0.25\%\) to \(0.65\%\)).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Surface irrigation methods (like furrows and borders) require precise land slopes to guide water down the field at a velocity that allows uniform infiltration without causing soil erosion.

Step 3: Detailed Explanation:
The recommended safe slope limits depend primarily on soil texture and erodibility:
-

Heavy clay soils: Safe slopes range from \(0.05\%\) to \(0.20\%\) because clay has low infiltration and can waterlog easily.
-

Medium loamy soils: Safe slopes range from \(0.20\%\) to \(0.40\%\) (sometimes up to \(0.5\%\)), balanced for medium infiltration.
-

Light sandy soils: Safe slopes can range from \(0.25\%\) to \(0.65\%\) (or higher) because high infiltration rates reduce runoff velocity and erosion risks.
For medium loamy soils, the correct range is \(0.20\%\) to \(0.40\%\).

Step 4: Final Answer:
The safe limits of land slope for loamy soils are 0.20 to 0.40 %.