Which of the following statements can help in water conservation in agriculture?

1. Reduced or zero tillage of the land.
2. Applying gypsum before irrigating the field.
3. Allowing crop residue to remain in the field.

Select the correct answer using the code given below:

The correct answer is 1 and 3 only.

Let us analyze each statement carefully to understand which practices genuinely contribute to water conservation in agriculture.

Statement 1: Reduced or zero tillage of the land.
This statement is correct. Tillage (ploughing and turning of soil) disrupts the soil structure and breaks up the soil aggregates. When soil is left undisturbed through reduced or zero tillage:

- The soil retains its natural pore structure, allowing better water infiltration and retention.
- Evaporation from the deeper soil layers is reduced because the capillary channels that bring moisture to the surface are not broken.
- Soil organic matter is preserved, which improves the soil's water-holding capacity.
- Reduced tillage also minimizes surface runoff, keeping more moisture within the field.
Therefore, reduced or zero tillage is a well-established water conservation technique.

Statement 2: Applying gypsum before irrigating the field.
This statement is incorrect in the context of water conservation. Gypsum (calcium sulphate) is primarily used as a soil amendment for reclaiming alkaline or sodic soils. It replaces the sodium ions in the soil with calcium ions, improving soil structure and permeability. While this may indirectly improve how water moves through waterlogged or sodic soils, it is not a direct water conservation measure. Its primary purpose is soil health/reclamation, not saving water. Hence, this statement cannot be categorized as a water conservation practice.

Statement 3: Allowing crop residue to remain in the field.
This statement is correct. Leaving crop residue (stubble, straw, leaves) on the field surface after harvest acts as a mulch layer. This provides several water-saving benefits:

- It physically covers the soil surface, shielding it from direct sunlight and wind, thereby drastically reducing evaporation.
- It slows surface runoff during rainfall or irrigation, giving water more time to infiltrate into the soil.
- It helps maintain soil moisture for longer periods between irrigation events.
- Over time, decomposing residue adds organic matter to the soil, further enhancing its water-holding capacity.
This practice is widely recommended under conservation agriculture and is a proven water conservation method.

Conclusion:
Statements 1 (reduced/zero tillage) and 3 (crop residue retention) are valid water conservation practices in agriculture. Statement 2 (gypsum application) is a soil reclamation technique, not a water conservation method. Therefore, the correct answer is "1 and 3 only".