Soils and Soil Fertility – Agriculture Optional PYQs (1995–2026)

Here are all 113 Soils and Soil Fertility questions asked in UPSC Agriculture Optional Paper I from 1995 to 2026, arranged under the 10 topics of the official syllabus. Within each topic the latest questions come first.

Each question ends with a code such as [2024/15m/3b] – the year, the marks, the word limit (where UPSC set one) and the question number in the paper.

5.1] Soil properties

12 questions

1. What do you mean by soil consistency and soil plasticity? Briefly discuss the various forms of soil consistency found in soils. [2026/20m/4a]

2. Give an account of the genesis of soil structure and its significance to crop production. [2023/10m/150w/1e]

3. Why do we consider soil structure an important soil property for crop production? How is soil structure changed by various factors? [2022/20m/4b]

4. What are important soil animals? Write their contributions to soil. [2014/10m/150w/5a]

5. Gravitational water and Hydroscopic water. [2013/10m/150w/3b]

6. Factors affecting soil structure. [2013/12.5m/200w/8b]

7. Soil Texture and Soil Structure. [2009/10m/3b]

8. Field Capacity and Water-holding Capacity. [2009/10m/3c]

9. Soil structure and steps for development. [2006/20m/200w/1b]

10. Particle Density. [2000/20m/200w/5c]

11. Define and differentiate between soil texture and soil structure. How do you determine soil texture? Give brief description of structural types with schematic drawings. [2000/60m/7]

12. Soil water. [1996/20m/200w/5d]

5.2] Soil formation and soils of India

5 questions

1. Write a brief note on the major soils of India. [2025/10m/2c]

2. Give a lucid account on the factors influencing soil formation. [2025/20m/6b]

3. Name the important minerals found in different rocks. Describe chemical weathering of soil. [2012/12m/150w/1a]

4. Differentiate between active and passive factors of soil formation. [2010/15m/4a]

5. Soil profile. [2005/20m/200w/5b]

5.3] Mineral and organic constituents of soils and soil productivity

12 questions

1. Explain the factors affecting soil organic matter content. Describe the techniques to increase soil organic matter. [2018/20m/2b]

2. Differentiate between soil fertility and soil productivity. What is meant by the organic matter content of good agricultural soil? Compare it with that of forest soil. Suggest ways to maintain soil organic matter content and improve crop productivity. [2016/20m/2b]

3. What benefits are derived from organic matter in soil? [2015/10m/150w/5b]

4. Organic and inorganic colloids of soil. [2011/10m/3c]

5. Organic Matter and Mineral Matter. [2009/10m/3f]

6. Soil Fertility and Soil Productivity. [2009/20m/200w/5d]

7. Mineralogical organisation of silicate clays. [2005/20m/200w/1c]

8. How does soil productivity differ from soil fertility? What are the factors responsible for degradation of soil productivity? Suggest practical measures to improve it. [2004/60m/4]

9. Carbon: Nitrogen ratio. [2003/20m/200w/5b]

10. Soil fertility & productivity. [2001/15m/8a]

11. Distinguish between soil-fertility and soil-productivity. Discuss in detail the factors affecting the productivity of the soil. [1999/60m/2]

12. Organic matter. [1998/20m/200w/1b]

5.4] Essential plant nutrients and beneficial elements

9 questions

1. Write down the functions and deficiency symptoms of secondary nutrients in plants. [2026/10m/150w/1e]

2. What is the Arnon and Stout (1939) criteria for plant nutrient essentiality? Give account of forms of each essential plant nutrient element absorbed by plants. [2024/20m/3a]

3. Biofortification. [2019/10m/150w/1a]

4. How are plant nutrients classified? What role do they play in crop productivity? [2017/20m/2a]

5. List out the criteria for essentiality of nutrients. Differentiate between essential, beneficial and functional elements in plant nutrition. How are these nutrient elements absorbed by the plants? [2016/20m/2a]

6. Give the criteria of essentiality of plant nutrients. List the essential mineral elements required in plant nutrition. State the principal functions of N, P, K, Ca, Mg and S. [2015/20m/6a]

7. Chelates and Boron carriers. [2012/15m/3c]

8. Name the essential elements required by plants. What are the sources of these elements? How are they lost from the soil and what are the measures to maintain their status in the soil? [2009/60m/2]

9. What are the essential elements required for the growth of higher plants? Write the role of trace elements. How is the availability of these affected in varying soil conditions? [2005/60m/6]

5.5] Soil fertility, soil testing and fertiliser recommendations

12 questions

1. Give account of soil fertility evaluation techniques. Enlist the points to be considered along with soil test values for fertiliser dose recommendation. [2024/10m/3c]

2. Kisan Credit Card and Soil Health Card. [2022/10m/150w/5b]

3. What do you mean by Site-Specific Nutrient Management (SSNM)? Write the steps and recommendations for implementing SSNM in major cereals. [2021/20m/3b]

4. What are the factors responsible for declining soil fertility? Discuss various measures adopted for improving soil productivity. [2021/20m/4a]

5. Describe the principles of soil fertility. Explain the role of biofertilizers in enhancing the soil fertility. [2020/10m/8c]

6. Soil health card. [2019/10m/150w/5c]

7. Soil health. [2017/10m/150w/1e]

8. Elaborate the ways to increase fertilizer use efficiency. [2015/20m/8a]

9. Harnessing synergy between water and nutrients for high crop productivity. [2010/15m/150w/1b]

10. Comment on soil test based nutrient recommendations for crops and their adoption by farmers. [2010/15m/4c]

11. Differentiate fertilizer-use-efficiency and fertilizer-utilization-efficiency. Discuss the important agrotechnique for increasing fertilizer-use-efficiency in rice in sandy loam soil. [1997/60m/4]

12. Soil fertility evaluation. [1995/20m/200w/5a]

5.6] Integrated nutrient management and biofertilisers

19 questions

1. What is the need for integrated nutrient management (INM)? Suggest INM for transplanted rice. [2025/10m/4c]

2. Describe the concept of microbial consortia and its role in crop residue management. [2023/10m/2c]

3. Discuss the relevance of Integrated Nutrient Management in sustainable agriculture. Describe various types of biofertilizers. [2022/20m/8b]

4. Biofertilizers and the major constraints in popularization of biofertilizers. [2021/10m/150w/1e]

5. What is integrated nutrient management (INM)? Explain the limitations in practice of INM at farmers level in India. [2020/10m/150w/5e]

6. Describe the principles of soil fertility. Explain the role of biofertilizers in enhancing the soil fertility. [2020/10m/8c]

7. Discuss the kinds of bio-fertilizers and their application methods. Give the reasons for their limited acceptance among the Indian farmers. [2018/20m/6b]

8. Integrated Pest Management (IPM) vs Integrated Nutrient Management (INM) [2016/10m/150w/1b]

9. Integrated nutrient management and Integrated pest management. [2015/10m/3a]

10. Inorganic fertilizers and Bio-fertilizers. [2013/10m/150w/3d]

11. Briefly discuss different aspects of integrated nutrient management and its limitations. [2012/15m/200w/2d]

12. Integrated nutrient management for sustainable agriculture. [2011/15m/150w/1b]

13. Chemical fertilizers and bio-fertilizers. [2011/10m/3d]

14. Differentiate between green manuring and biofertilizers for crop production. [2010/15m/4d]

15. Integrated Nutrient Management. [2002/20m/200w/1c]

16. Azolla as Bio-fertilizer. [2002/20m/200w/5b]

17. What do you mean by IPNM? Discuss it in the context of rice-wheat cropping system. [2001/60m/3]

18. Bio-fertilizers. [1999/20m/200w/5a]

19. Define and discuss the role of integrated nutrient management in Indian agriculture. [1998/60m/4]

5.7] Nitrogen in soils

18 questions

1. What is nitrification? Describe the factors affecting nitrification process in soil. [2026/20m/4b]

2. What are the two steps of nitrification and enlist micro-organisms responsible for each? Write down the importance of nitrification. [2024/10m/150w/1e]

3. Discuss the primary pathways of gaseous nitrogen losses from soil and the factors affecting nitrogen losses. [2023/20m/4a]

4. How to enhance nitrogen use efficiency in transplanted rice? [2022/10m/150w/1e]

5. Leaf colour chart and its use for nitrogen management in rice crop. [2019/10m/150w/5a]

6. What changes occur in rice puddled soil? Describe the fate of nitrogen and practices for enhancing nitrogen use efficiency in such soils. [2018/20m/4a]

7. Discuss nitrogen transformation and its management in submerged soil for rice production. [2015/20m/4a]

8. What do you understand by slow release nitrogen from nitrogenous fertilizers? What is its importance? [2014/20m/8c]

9. Discuss the nitrogen losses from water-logged soil. What are the various practices to increase nitrogen use efficiency in submerged rice? [2013/25m/400w/7b]

10. Mineralization and immobilization. [2011/10m/3f]

11. N-use-efficiency vs. N-utilization-efficiency [?]. [2007/20m/200w/1d]

12. Symbiosis. [2007/20m/200w/5c]

13. How does the nitrogen become available to plants when urea is applied to soil? Briefly write on nitrogen use efficiency under submerged paddy conditions. [2006/60m/3]

14. Write the nitrogen transformation processes in soils. What changes does nitrogen undergo regarding losses and availability? Why are legume crops beneficial in nitrogen fixation? [2005/60m/3]

15. N-application in submerged soils in rice. [2001/15m/4c]

16. Describe the role of nitrification inhibitors with mechanism of their working and suitable examples. [2000/60m/6]

17. Nitrification inhibitors. [1996/20m/200w/1c]

18. Nitrogen fixation in legume. [1995/20m/4c]

5.8] Efficient phosphorus and potassium use

6 questions

1. Briefly discuss the reasons responsible for increasing available phosphorus after flooding, in most of the soils. [2026/10m/4c]

2. What are the reasons for low availability of phosphorus nutrient? Give an account of agronomic practices to improve the phosphorus-use efficiency. [2019/20m/8a]

3. Describe the potassium fixation in soil and factors affecting it. [2012/15m/200w/8a]

4. Fixation of phosphorus and potassium in soil. [2003/20m/200w/1d]

5. Phosphorus in Crop Production. [2000/20m/200w/5d]

6. Potassium in crop production. [1998/20m/200w/1c]

5.9] Problem soils and their reclamation

18 questions

1. Enunciate the reasons for waterlogging and describe various management strategies to mitigate waterlogging. [2025/20m/7b]

2. Discuss the causes of waterlogging and its effects on crop production. [2023/10m/8c]

3. How soil acidity affects crop production? Elaborate the remedial procedures of soil acidity. [2022/20m/3a]

4. What do you mean by problematic soil? How soil is converted into problematic soil? Explain various methods of reclamation of saline-alkali-soils. [2020/20m/7b]

5. Differentiate between saline and sodic soils. Give an account of agro-techniques for management of these soils. [2019/20m/6b]

6. Problems and reclamation of saline and sodic soils. [2018/10m/150w/5c]

7. Describe ‘soil salinity’. Enumerate various methods for soil reclamation. [2017/10m/4c]

8. How does soil acidity affect the crops? [2015/10m/2c]

9. Lime requirement and Leaching requirement. [2015/10m/3e]

10. Problems of waterlogged soils. [2011/15m/8a]

11. What are the management strategies for tackling the major soil-related constraints in agricultural production? [2010/30m/3b]

12. Discuss saline and alkaline soils under the following subheads: Classification and characteristics. [2009/20m/7a]

13. Discuss saline and alkaline soils under the following subheads: Causes of formation. [2009/20m/7b]

14. Discuss saline and alkaline soils under the following subheads: Remedial measures. [2009/20m/7c]

15. Write the characteristics and process of formation of acidic soil. What part of India is affected by acidic soils? How these soils can be cultivated for efficient crop production? [2003/60m/2]

16. Acid soils reclamation. [1998/20m/200w/1d]

17. Sodic soils. [1996/20m/200w/5a]

18. Write the characteristics and the process of formation of saline and alkali soils. How these soils can be cultivated for efficient crop production? [1995/60m/2]

5.10] Soil factors affecting greenhouse gas emission

2 questions

1. Explain the term conventional and conservation tillage. Give account of their comparative effects on soil properties and green house gas emissions. [2024/20m/4a]

2. Soil factors affecting greenhouse gases emission. [2012/12m/150w/5a]

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Last updated: 30 October 2026