What are the advantages of fertigation in agriculture 1) Controlling the alkalinity of irrigation water is possible. 2) Efficient application of Rock Phosphate and all other phosphatic fertilizers is possible. 3) Increased available of nutrients to plants is possible. 4) Reduction in the leaching of chemical nutrients is possible. Select the correct answer using the code given below:

Fertigation means supplying fertilisers dissolved in irrigation water, so the question is really about what a water-soluble nutrient delivery system can and cannot do. The answer is C, statements 1, 3 and 4.

• Statement 1 is correct. Alkaline irrigation water (high bicarbonate) can be neutralised by injecting acids such as sulphuric or phosphoric acid through the system.
• Statement 2 is wrong. Rock phosphate is insoluble in water and cannot be applied through drip or sprinkler lines. Phosphatic fertilisers are also fixed in soil, so fertigation is not an efficient route for them.
• Statement 3 is correct. Nutrients are placed in the root zone in small, frequent doses, which keeps them available to the plant.
• Statement 4 is correct. Precise, measured application reduces losses through deep percolation, which lowers nitrate leaching.

Core concept: nutrient-use efficiency through micro-irrigation. This links to the Mains theme of water-use efficiency and sustainable agriculture, including the Per Drop More Crop component of PMKSY.

Trap: candidates tend to accept statement 2 because fertigation is 'efficient' in general. Only soluble fertilisers suit it, and rock phosphate does not dissolve in water.