Protected Cultivation & Landscaping

• Crop Coefficient Approaches in Evapotranspiration (FAO-56):
• Statement (I): Single crop coefficient approach is used for surface irrigation methods. $\implies$ Correct.
• In surface (border, furrow, basin) irrigation where the entire soil surface is wetted periodically, crop transpiration and soil evaporation are combined into a single time-averaged crop coefficient ($K_c$), yielding $ET_c = K_c \cdot ET_0$.
• Statement (II): Dual crop coefficient approach is used for micro irrigation methods. $\implies$ Correct.
• In drip/micro irrigation where only a small fraction of the soil surface is wetted frequently, $K_c$ is partitioned into basal crop transpiration ($K_{cb}$) and soil surface evaporation ($K_e$), yielding $ET_c = (K_{cb} + K_e) ET_0$.
• Conclusion: Both Statement (I) and Statement (II) are correct (Option 1).

Correct option: (1) Both Statement (I) and Statement (I) are correct

Analyzing the statements in relation to Water gains and water losses from soil:

The correct option is Option 2: Both Statement (I) and Statement (Il) are incorrect.

• Sprinkler Nozzle Selection Criteria:
• Selection of agricultural sprinkler heads and nozzles is governed by three interdependent operational parameters:
• Diameter of coverage ($D$): Defines the wetted radius and determines allowable lateral and sprinkler spacing ($S_l \times S_m$) under prevailing wind conditions.
• Operating pressure available ($P$): Determines jet trajectory, droplet break-up, and nozzle flow rate.
• Sprinkler discharge ($q$): Governs the application rate ($I_a = \frac{q \times 1000}{S_l \times S_m}\text{ mm/h}$), which must strictly not exceed the basic soil infiltration rate to prevent surface runoff and ponding.
• Conclusion: (A), (B) and (C) (Option 4).

Correct option: (4) (A), (B) and (C).

• Concrete Mix Ratios for Canal Lining:
• In agricultural water conveyance, cement concrete lining reduces seepage losses and prevents weed growth.
• The Bureau of Indian Standards (IS: 3873) recommends nominal mix proportions for canal bed and side linings of 1:3:4 or 1:3:5 (Cement : Sand : Coarse Aggregate).
• 3:4 provides optimal impermeability and tensile resistance against hydrostatic backpressure.
• Conclusion: 1:3:4 (Option 4).

Correct option: (4) 1:3:4