Correct Option: B Explanation of the Correct Answer Sub-surface irrigation is a method where water is delivered below the soil surface, directly to the root zone of plants. This technique has several advantages, but the statement that it "can be used only for specific types of crops" (Option B) is misleading and incorrect.

1. Versatility of Crops: Sub-surface irrigation can be used for a wide variety of crops, not just specific types. It is particularly beneficial for crops that require consistent moisture levels, such as vegetables, fruits, and some grains. The ability to adjust the water supply according to the needs of different crops makes it a versatile option for many agricultural practices.
2. Water Efficiency: This method is designed to minimize water loss through evaporation and runoff, making it suitable for various soil types and crop requirements. It can be adapted to different agricultural systems, whether for row crops, orchards, or even turf management.

Explanation of Why Other Options Are Incorrect or Weaker

• Option A: It is suitable for soils with low water holding capacity This statement is true. Sub-surface irrigation is particularly advantageous in soils that do not retain water well, as it allows for more efficient water use. By delivering water directly to the root zone, it reduces the amount of water lost to evaporation and ensures that plants receive the moisture they need.
• Option C: The rate of evaporation is greatly reduced This statement is also true. One of the primary benefits of sub-surface irrigation is that it significantly reduces evaporation losses compared to surface irrigation methods. Since the water is applied below the surface, it is less exposed to the air, which minimizes evaporation and helps maintain soil moisture levels.
• Option D: It reduces the incidence of pests This statement is partially true but not a primary advantage of sub-surface irrigation. While it can help reduce certain pest problems by keeping the soil surface drier (which may deter some surface-dwelling pests), it does not inherently reduce all pest incidences. Pests can still thrive in moist environments, especially if the conditions are favorable for their growth. Therefore, while it may contribute to pest management, it is not a guaranteed or significant advantage of sub-surface irrigation.

Summary of Key Points

• Sub-surface irrigation is versatile and can be used for a wide range of crops, making Option B the correct answer.
• It is particularly effective in soils with low water holding capacity (Option A).
• The method significantly reduces evaporation rates (Option C).
• While it may help manage some pests, it is not a primary advantage (Option D).

Revision Summary

• Sub-surface irrigation is adaptable for various crops, not limited to specific types.
• It is effective in low water holding capacity soils.
• This method reduces evaporation significantly.
• Pest incidence may be affected, but it is not a primary benefit of sub-surface irrigation.