Which of the following practices 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:

Let's analyze each statement in relation to water conservation in agriculture:

Statement 1: Reduced or zero tillage of the land

Tillage involves mechanically agitating the soil (e.g., digging, stirring). Zero tillage (or no-till farming) avoids disturbing the soil. This practice helps in soil moisture conservation by reducing evaporation and improving water infiltration.

Therefore, statement 1 is correct.

Statement 2: Applying gypsum before irrigating the field

Gypsum primarily improves soil structure and provides calcium and sulfur. While it can improve water infiltration in certain soil types (especially sodic soils), it's not a direct water conservation technique applicable universally. Gypsum does not directly neutralize soil acidity or raise the pH significantly for water conservation purposes.

Therefore, statement 2 is not correct.

Statement 3: Allowing crop residue to remain in the field

Crop residue (the material left after harvesting) acts as a mulch. It reduces soil erosion by wind and water, conserves soil moisture by reducing evaporation, and provides thermal protection to plants.

Therefore, statement 3 is correct.

Hence, only statements 1 and 3 are correct.