Question

What is the optimum range of soil moisture for effective ploughing?

• A. 5 to 10 per cent depletion of available soil moisture
• B. 15 to 20 per cent depletion of available soil moisture
• C. 25 to 50 per cent depletion of available soil moisture
• D. 50 to 60 per cent depletion of available soil moisture

Hint:

Recall the friable moisture range where soil crumbles instead of smearing or clodding.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
We are asked for the range of soil moisture depletion at which ploughing gives the best results.

Step 2: Key Formula or Approach:
Soil behaves differently at different moisture levels during tillage. When the soil is too wet, close to field capacity, ploughing smears and puddles the soil and it dries into hard clods later. When the soil is too dry, close to the wilting point, it takes much more force to break the soil and it breaks into hard, angular clods instead of a fine, workable tilth. There is a middle range, called the friable range, where the soil crumbles easily and gives the best tilth with the least effort.

Step 3: Detailed Explanation:
This friable, easy to work condition is reached once the available soil moisture has been used up to about 50 to 60 per cent, that is, the soil has dried down partway from field capacity but not so far that it turns into hard, dry clods. Ploughing outside this window, either too early when the field is still wet or too late when the field is nearly dry, leads to poor tilth and higher power needs. Ranges as low as 5 to 20 per cent depletion describe soil that is still too wet for good tillage, since so little of the available water has been lost yet.

Step 4: Final Answer:
The optimum range for effective ploughing is 50 to 60 per cent depletion of available soil moisture, which is option 4.