Q35. Which two elements are primarily added to soil by green manure?
[RRB JE CBT 1 (20 February 2026, Shift 1)]
(A) Phosphorus and calcium
(B) Potassium and magnesium
(C) Nitrogen and phosphorus
(D) Nitrogen and potassium
Answer: (C) Nitrogen and phosphorus
Explanation: Green manuring means growing a crop, often a legume, and incorporating it into the soil while green. It adds nitrogen-rich biomass and organic matter, improves soil microbial activity, and supports phosphorus cycling. The examination’s intended pair is nitrogen and phosphorus.
Q34. What is a key difference between chemical fertilisers and manures in terms of nutrient release to plants?
[RRB JE CBT 1 (20 February 2026, Shift 1)]
(A) Manures have higher and less variable nutrient concentrations.
(B) Conventional chemical fertilisers release nutrients gradually.
(C) Chemical fertilisers enhance biological activity.
(D) Manures release nutrients gradually.
Answer: (D) Manures release nutrients gradually.
Explanation: Most nutrients in manure are tied up in organic substances and become available as microorganisms decompose them. Conventional soluble chemical fertilisers generally provide nutrients more rapidly. Manure also improves soil structure and biological activity, although its nutrient composition is less predictable.
Q33. Why is using compost or vermi-compost preferable to excessive use of fertilizers for increasing soil fertility?
[RRB JE CBT 1 (19 February 2026, Shift 1)]
(A) It eliminates bacterial and viral plant diseases.
(B) It supplies only micro-nutrients and avoids macronutrients.
(C) It recycles biological waste and avoids environmental harm.
(D) It replaces the need for irrigation and weeding.
Answer: (C) It recycles biological waste and avoids environmental harm.
Explanation: Compost and vermicompost recycle decomposed organic waste into useful soil amendments. They contribute organic matter, improve soil structure and water retention, and supply nutrients gradually. Using them appropriately can reduce reliance on excess chemical fertilisers and the associated runoff and pollution risks.
Q32. Which chemical fertiliser is most widely used in agriculture as a concentrated source of nitrogen for crops?
[Delhi Police Head Constable AWO/TPO 2025 (16 January 2026, Shift 1)]
(A) Urea, CO(NHā)ā
(B) Gypsum, CaSOāĀ·2HāO
(C) Limestone, CaCOā
(D) Potassium chloride, KCl
Answer: (A) Urea, CO(NHā)ā
Explanation: Urea contains approximately 46% nitrogen by mass, making it a concentrated and widely used nitrogenous fertiliser. Soil enzymes convert urea into ammonium-containing forms. Gypsum supplies calcium and sulphur, limestone treats acidic soils, and potassium chloride primarily supplies potassium.
Q31. Consider the following statements and select the correct option.
Statement A: Plants require specific soil pH for proper growth.
Statement B: Farmers use pH values to decide the type of fertiliser to add.
[RRB Group D (29 December 2025, Shift 3)]
(A) Both statements A and B are correct.
(B) Statement A is correct but B is incorrect.
(C) Statement A is incorrect but B is correct.
(D) Both statements A and B are incorrect.
Answer: (A) Both statements A and B are correct.
Explanation: Soil pH controls the availability of many plant nutrients and influences microbial activity. Different crops tolerate different pH ranges. Farmers use soil tests, including pH measurements, when choosing suitable fertilisers or amendments and determining whether lime or other corrections are needed.
Q30. Manure prepared with the help of earthworms is called:
[UPPSC LT Grade Assistant Teacher, Hindi (6 December 2025, Shift 2)]
(A) Compost
(B) Vermicompost
(C) Green manure
(D) Farm yard manure
Answer: (B) Vermicompost
Explanation: Vermicompost is obtained when earthworms process biodegradable plant and animal residues. Their castings contain stabilised organic matter, useful nutrients and microorganisms. Ordinary composting does not specifically require earthworms; green manure uses incorporated growing plants, while farmyard manure comes mainly from livestock wastes.
Q29. Which of the following raw materials for the fertiliser industry is entirely imported as India does not have any reserves?
[DSSSB TGT Natural Science (6 September 2025, Shift 2)]
(A) Sulphur (S)
(B) Nitrogen (N)
(C) Potash (K)
(D) Phosphate (P)
Answer: (C) Potash (K)
Explanation: The paper identifies potash as the imported fertiliser raw material. India has historically relied heavily on imported potassic fertilisers because commercially exploitable domestic supplies are limited. Potassium is important for water regulation, enzyme function and crop quality; muriate of potash is a common source.
Q28. Which one of the following is classified as a complex fertilizer?
[UPSSSC Agriculture Technical Assistant Mains (13 July 2025)]
(A) Single Super Phosphate (SSP)
(B) Urea
(C) Muriate of Potash
(D) Di-Ammonium Phosphate (DAP)
(E) None of the above
Answer: (D) Di-Ammonium Phosphate (DAP)
Explanation: Diammonium phosphate supplies two primary plant nutrients: nitrogen and phosphorus. Its commercial grade is commonly expressed as 18-46-0, meaning 18% nitrogen and 46% available phosphate as PāOā . Urea and muriate of potash chiefly supply one primary nutrient each.
Q27. Chemical fertilisers were used intensively during the Green Revolution. What was the result of their overuse?
[RRB NTPC Graduate CBT-I (19 June 2025, Shift 3)]
(A) Crop diversification
(B) Soil salinity
(C) Higher pest resistance
(D) Flooding
Answer: (B) Soil salinity
Explanation: Repeated, poorly balanced fertiliser use, particularly alongside intensive irrigation, can contribute to salt accumulation and deteriorating soil quality. High salinity makes water uptake difficult for plants. Proper nutrient management, drainage, testing and irrigation practices help prevent such long-term damage.
Q26. The Paramparagat Krishi Vikas Yojana (PKVY) launched in 2015ā16 by the Central Government is aimed to:
[UPSC CDS-I General Knowledge (13 April 2025)]
(A) Make agriculture more modern and globally competitive.
(B) Provide improved access to irrigation and enhanced water efficiency.
(C) Support promotion of organic farming in the country.
(D) Reduce dependence of agriculture on monsoon.
Answer: (C) Support promotion of organic farming in the country.
Explanation: PKVY supports organic cultivation through farmer clusters, capacity building, certification and use of natural inputs. The scheme encourages compost, green manure and biofertilisers as alternatives to excessive synthetic inputs. Its primary purpose is organic farming, not irrigation expansion or monsoon management.
Q25. The Fertilizer Corporation of India has established coal-based chemical fertilizer plant in which of the following districts of Chhattisgarh?
[CGPSC Preliminary GS Paper I (9 February 2025)]
(A) Raigarh
(B) Korba
(C) Raipur
(D) Durg
Answer: (B) Korba
Explanation: The examination identifies Korba, a Chhattisgarh district known for major coal deposits. Coal can be gasified to obtain synthesis gas used in producing ammonia, which is a feedstock for urea. This connects the availability of coal with nitrogenous fertiliser manufacture.