UPSC Prelims 2020 Q91: Environment & Ecology – Sustainable Agriculture & Forestry
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:
- (a) 1, 2 and 3 only
- (b) 1, 2 and 4 only
- (c) 1, 3 and 4 only
- (d) 2, 3 and 4 only
Answer: (c) 1, 3 and 4 only
Explanation
Fertigation
Fertigation means giving fertilizer dissolved in irrigation water, usually through drip or sprinkler systems.
So only water-soluble fertilizers can be used.
| Statement | Verdict | Reason |
|---|---|---|
| 1. Controlling the alkalinity of irrigation water is possible | Correct | Acids or acidic fertilizers are injected with the water to lower its alkalinity |
| 2. Efficient application of Rock Phosphate and all other phosphatic fertilizers is possible | Incorrect | Rock phosphate is insoluble in water; several phosphatic fertilizers form deposits that clog the drippers |
| 3. Increased availability of nutrients to plants is possible | Correct | Nutrients reach the root zone in small, frequent doses |
| 4. Reduction in the leaching of chemical nutrients is possible | Correct | Only the needed amount is given, so little is washed below the roots |
Other gains from fertigation:
| Gain | Detail |
|---|---|
| Saves fertilizer | Use can fall by about a quarter or more |
| Saves labour and water | One operation does both jobs |
| Uniform supply | Each plant gets the same dose |
Answer: (c) 1, 3 and 4 only.
Why each option is right or wrong
- (a) Incorrect. Statement 2 is false; Rock Phosphate does not dissolve in water.
- (b) Incorrect. Statement 2 is false, and Statement 3 on nutrient availability is left out.
- (c) CORRECT. Fertigation controls alkalinity, raises nutrient availability and reduces leaching.
- (d) Incorrect. Statement 2 is false, and Statement 1 on alkalinity is left out.
Key point
Fertigation: soluble fertilizers through drip irrigation; raises nutrient-use efficiency, cuts leaching, allows acid injection; not for rock phosphate, which is insoluble.
Remember
Fertigation = fertilizer + irrigation; soluble fertilizers only.
Common mistakes
- Passing Statement 2 without noticing 'all other phosphatic fertilizers'.
- Doubting Statement 1; acid injection is a standard practice in drip systems.
- Confusing fertigation with foliar spray or with broadcasting fertilizer.
Exam tip
Fertigation needs fertilizers that dissolve. Rock phosphate is a rock powder, so the statement fails.
Sources
- Indian Council of Agricultural Research — Handbook of Agriculture (micro-irrigation and fertigation)
- National Committee on Plasticulture Applications in Horticulture — Fertigation guidelines