Previous Year Question
Which of the following practices can help in water conservation in agriculture?
Reduced or zero tillage of the land
Applying gypsum before irrigating the field
Allowing crop residue to remain in the field
Select the correct answer using the codes given below.
1 and 2
Only 3
1 and 3
1, 2 and 3
Correct Answer: C
Detailed Solution
Statement 1 is correct: Under reduced or zero tillage, the soil is not repeatedly turned over. Consequently, soil structure and the continuity of soil pores remain relatively protected. The surface cover reduces evaporation, runoff and soil erosion, while increasing water infiltration and the conservation of moisture in the soil. Zero tillage also reduces the repeated mechanical operations required for field preparation.
Statement 2 is not correct: Gypsum is calcium sulphate and is primarily used as an amendment for sodic or alkaline soils. The calcium supplied by gypsum replaces sodium from the exchange sites of the soil. This improves soil structure and permeability and permits the displaced sodium to be leached downward. Although gypsum may improve water infiltration in sodic soils, applying gypsum before irrigation is not a general agricultural water-conservation practice. It is a method for reclaiming a particular type of problem soil.
Statement 3 is correct: When crop residues are left in the field, they act as mulch. The residue cover reduces the direct impact of raindrops, surface crusting, water runoff and soil erosion. It lowers evaporation, regulates soil temperature and increases infiltration and conserved soil moisture. In the long term, it may also increase the organic-matter content of the soil.