Question

Read the following statements about border irrigation carefully:
A. Width of borders usually varies from 10 to 25 m.
B. For a sandy and sandy loam soil on moderate slopes and small to moderate irrigation streams, border length ranges from 30 to 90 m.
C. For a medium loam soil on moderate slopes and small to moderate irrigation streams, border length ranges from 100 to 180 m.
D. For a clay loam and clay soil on moderate slopes and small to moderate irrigation streams, border length ranges from 120 to 350 m.
Choose the correct answer from the options given below:

• A. A, B and D only
• B. C only
• C. A and D only
• D. B, C, and D

Hint:

In border irrigation design, the length of the border is directly proportional to the soil texture (heaviness): - Coarse soils (sand): Short borders. - Medium soils (loam): Medium borders. - Fine soils (clay): Long borders.

Answer 1

The Correct Option is C

Step 1: Evaluate each statement about border irrigation design parameters.
- Statement A: The width of a border strip is chosen based on the land slope and the size of farm machinery. A range of 10 to 25 m is a typical, reasonable range for many conditions. This statement is generally correct.
- Statement B: Sandy and sandy loam soils have very high infiltration rates. To ensure water reaches the end of the border before it all infiltrates, the border length must be kept relatively short. A range of 30 to 90 m is too long for these soil types; lengths are usually shorter. This statement is likely incorrect.
- Statement C: Medium loam soils have moderate infiltration rates. This allows for longer border lengths than sandy soils. A range of 100 to 180 m is a suitable and common recommendation for these conditions. This statement is correct.
- Statement D: Clay loam and clay soils have low infiltration rates. Water travels a long distance before infiltrating, so border lengths can be very long. A range of 120 to 350 m is appropriate for these heavy soils. This statement is correct.
Step 2: Conclude the correct combination.
Statements A, C, and D represent correct design principles for border irrigation. Statement B suggests lengths that are too long for coarse-textured soils.
Therefore, A, C, and D is the best combination.