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 availability 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:

1. Controlling the alkalinity of irrigation water is possible — Correct. In fertigation, acids/acid-forming fertilizers can be injected through irrigation systems, which helps manage alkaline irrigation water.

2. Efficient application of Rock Phosphate and all other phosphatic fertilizers is possible — Incorrect. Fertigation needs fully water-soluble fertilizers; rock phosphate is not water-soluble and is generally unsuitable for fertigation.

3. Increased availability of nutrients to plants is possible — Correct. Nutrients are supplied directly with irrigation water near the root zone, improving nutrient availability and uptake.

4. Reduction in the leaching of chemical nutrients is possible — Correct. Small, frequent, targeted application through fertigation reduces nutrient losses, including leaching.

Hence, 1, 3 and 4 only are correct.