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Exam
Question 1. Which macronutrient is most mobile in the phloem, allowing it to be redistributed from older to younger leaves? A) Nitrogen B) Phosphorus C) Potassium D) Calcium Answer: C Explanation: Potassium moves readily in the phloem and can be translocated to growing tissues. Question 2. The primary form of nitrogen taken up by most crop plants from the soil solution is: A) NH₄⁺ B) NO₃⁻ C) N₂ gas D) Urea Answer: B Explanation: Nitrate (NO₃⁻) is the dominant inorganic nitrogen form absorbed by roots. Question 3. Which soil property most directly influences its cation exchange capacity (CEC)? A) Sand content B) Clay mineral type C) Bulk density D) Soil temperature Answer: B Explanation: Clay minerals and organic matter provide the negative charges that determine CEC.
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Question 4. A soil test shows a pH of 5.2. Which nutrient is most likely to be deficient because of low pH? A) Manganese B) Zinc C) Phosphorus D) Sulfur Answer: C Explanation: Phosphorus availability drops sharply in strongly acidic soils. Question 5. The recommended lime requirement for a soil with a pH of 5.0, target pH 6.5, and a buffer pH of 7.0 is 2.5 t/ha. This calculation is based on which principle? A) Neutralization of acidity B) Increasing CEC C) Adding organic matter D) Enhancing microbial activity Answer: A Explanation: Lime neutralizes exchangeable acidity to raise soil pH. Question 6. Which of the following is a micronutrient that is immobile in the plant and therefore must be supplied continuously? A) Iron B) Calcium C) Magnesium D) Sulfur Answer: A
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Answer: C Explanation: Field capacity is the water retained in the soil after gravitational drainage. Question 10. A soil with an electrical conductivity (EC) of 6 dS m⁻¹ is considered: A) Non‑saline B) Slightly saline C) Moderately saline D) Highly saline Answer: D Explanation: EC > 4 dS m⁻¹ generally indicates high salinity, detrimental to most crops. Question 11. Which of the following is a biological weed‑control method? A) Crop rotation B) Mulching C) Introduction of a weed‑feeding beetle D) Mechanical tillage Answer: C Explanation: Using a natural enemy, such as a beetle that feeds on weeds, is a biological control. Question 12. The critical period for weed control (CPWC) is defined as: A) The time from sowing to emergence B) The stage when weeds cause irreversible yield loss if not controlled C) The period when herbicides are most effective D) The interval between two successive herbicide applications Answer: B
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Explanation: CPWC is the window during which weed competition must be avoided to prevent yield loss. Question 13. Which herbicide mode of action is associated with inhibition of acetyl‑CoA carboxylase (ACCase)? A) ALS inhibitors B) EPSP synthase inhibitors C) ACCase inhibitors D) Photosystem II inhibitors Answer: C Explanation: ACCase‑inhibiting herbicides block fatty‑acid synthesis in grasses. Question 14. An insect pest that overwinters as an egg on crop residues is best managed by: A) Crop rotation B) Early planting C) Removing residues (stubble management) D) Applying foliar insecticide at flowering Answer: C Explanation: Destroying the overwintering site (residues) reduces the egg population. Question 15. The economic threshold (ET) for a pest is defined as: A) The pest density that causes any damage B) The pest density at which control costs equal damage loss C) The maximum allowable pesticide residue on produce D) The population level at which a pest becomes a legal pest
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D) Late planting date Answer: A Explanation: Rotating crops breaks the disease cycle by removing the host. Question 19. The term “integrated pest management (IPM)” emphasizes: A) Exclusive use of chemical controls B) Combining cultural, biological, mechanical, and chemical tactics C) Maximum pesticide application rates D) Use of genetically modified crops only Answer: B Explanation: IPM integrates multiple control methods to manage pests sustainably. Question 20. Which of the following is a key benefit of cover crops? A) Immediate cash income B) Increased soil erosion C) Enhanced soil organic matter and nitrogen fixation D) Higher pesticide requirement Answer: C Explanation: Cover crops improve organic matter, protect against erosion, and some fix nitrogen. Question 21. The bulk density of a soil is most directly affected by: A) Soil texture only B) Soil organic matter content C) Soil pH
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D) Soil temperature Answer: B Explanation: Higher organic matter reduces bulk density by increasing porosity. Question 22. In a loam soil, the approximate percentages of sand, silt, and clay are: A) 70 % sand, 20 % silt, 10 % clay B) 40 % sand, 40 % silt, 20 % clay C) 20 % sand, 30 % silt, 50 % clay D) 10 % sand, 20 % silt, 70 % clay Answer: B Explanation: Loam typically contains roughly equal sand and silt with moderate clay. Question 23. Which soil conservation practice involves planting rows perpendicular to the slope? A. Terracing B. Contour plowing C. Strip cropping D. No‑till farming Answer: B Explanation: Contour plowing follows the land’s contour, reducing runoff. Question 24. The term “field capacity” refers to: A. The water content after a wet soil drains for 24 h B. The water held at the wilting point C. The maximum amount of water a soil can hold against gravity
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D. Low organic matter Answer: A Explanation: High SAR indicates excess sodium, leading to dispersion and poor structure. Question 28. The most common method for removing excess water from a water‑logged field is: A. Surface leveling B. Subsurface tile drainage C. Mulching D. Deep plowing Answer: B Explanation: Tile drainage provides a pathway for water to exit the root zone. Question 29. Which of the following is an example of a mechanical weed‑control method? A. Herbicide application B. Crop rotation C. Rotary hoeing D. Use of allelopathic cover crops Answer: C Explanation: Mechanical removal, such as hoeing, physically kills weeds. Question 30. The “critical nutrient deficiency” that leads to interveinal chlorosis in young leaves is most often a lack of: A. Nitrogen B. Phosphorus
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C. Magnesium D. Calcium Answer: C Explanation: Magnesium deficiency shows as yellowing between veins of new leaves. Question 31. Which of the following fertilizer sources provides the highest proportion of nitrogen as ammonium (NH₄⁺) at application? A. Urea B. Ammonium nitrate C. Anhydrous ammonia D. Calcium nitrate Answer: C Explanation: Anhydrous ammonia is applied as NH₃ gas, quickly forming NH₄⁺ in soil. Question 32. The term “luxury consumption” in plant nutrition refers to: A. Uptake of nutrients beyond the plant’s immediate needs B. Excessive fertilizer application causing runoff C. Nutrient loss through leaching D. Nutrient deficiency symptoms Answer: A Explanation: Plants may absorb more of a nutrient than required for growth, storing it. Question 33. Which soil test parameter is most directly used to estimate the lime requirement? A. Soil organic carbon
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A. Sandy with low organic matter B. Loamy with moderate organic matter C. Clayey with high organic matter D. Rocky and shallow Answer: C Explanation: Clay particles and organic matter increase water retention. Question 37. Which of the following is a characteristic of a “good” seed? A. Low germination percentage B. High moisture content C. High vigor and uniformity D. Presence of weed seeds Answer: C Explanation: High vigor and uniform germination ensure reliable stand establishment. Question 38. The term “Growing Degree Days (GDD)” is used to: A. Measure soil moisture B. Predict pest emergence based on temperature accumulation C. Calculate fertilizer nutrient release rates D. Determine leaf area index Answer: B Explanation: GDD sums daily temperature excess above a base to forecast development stages. Question 39. Which planting geometry would increase plant population per hectare for a corn crop?
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A. Wider row spacing, same seed rate B. Narrower row spacing, same seed rate C. Same row spacing, lower seed rate D. Same row spacing, higher seed rate Answer: D Explanation: Increasing seed rate while keeping row spacing constant raises plant density. Question 40. A crop that is harvested at physiological maturity but before grain moisture reaches 20 % will likely suffer: A. Reduced grain size B. Increased lodging C. Higher post‑harvest drying costs D. Improved protein content Answer: C Explanation: Harvesting too early leads to higher grain moisture, requiring more drying. Question 41. Which post‑harvest practice helps prevent aflatoxin contamination in stored maize? A. Storing at >30 °C and high humidity B. Rapid drying to ≤13 % moisture and proper aeration C. Mixing with other grains D. Storing in sealed plastic bags without ventilation Answer: B Explanation: Drying to low moisture and keeping storage dry inhibits fungal growth and aflatoxin production.
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Question 45. Which of the following is a major advantage of no‑till (conservation) tillage? A. Immediate increase in soil temperature B. Higher erosion rates C. Improved soil organic matter retention D. Increased fuel consumption Answer: C Explanation: No‑till leaves residues on the surface, protecting soil and building organic matter. Question 46. A “critical nutrient” that commonly limits legume growth under acidic soils is: A. Calcium B. Molybdenum C. Sulfur D. Sodium Answer: B Explanation: Molybdenum deficiency is aggravated by low pH and limits nitrogen fixation in legumes. Question 47. Which of the following is a primary factor influencing the rate of mineralization of organic nitrogen in soil? A. Soil pH B. Soil color C. Soil temperature D. Soil texture Answer: C Explanation: Higher temperatures accelerate microbial activity and mineralization.
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Question 48. In a drip irrigation system, the term “emitters” refers to: A. Sensors that measure soil moisture B. Devices that control the flow of water to each plant C. Tubes that transport water from the pump D. Filters that remove debris from water Answer: B Explanation: Emitters regulate the amount of water delivered at each point. Question 49. Which of the following is an example of a “synthetic” pesticide? A. Neem oil B. Bacillus thuringiensis (Bt) C. Atrazine D. Copper sulfate Answer: C Explanation: Atrazine is a man‑made chemical herbicide. Question 50. The “soil‑water holding capacity” is greatest in soils that are: A. Sandy with low organic matter B. Loamy with moderate organic matter C. Clayey with high organic matter D. Rocky and shallow Answer: C Explanation: Clay particles and organic matter increase water retention.
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Question 54. In a soil test, a high level of exchangeable aluminum is most likely to indicate: A. High pH (alkaline) soil B. Low CEC C. Acidic soil conditions D. Saline soil Answer: C Explanation: Aluminum becomes soluble and toxic in acidic soils (pH < 5). Question 55. Which of the following practices directly reduces nitrogen leaching from a field? A. Applying fertilizer before a heavy rain event B. Using deep placement of nitrogen fertilizer C. Applying nitrogen in a single large dose at planting D. Using high‑rate urea without inhibitors Answer: B Explanation: Deep placement places nitrogen closer to roots, reducing movement beyond the root zone. Question 56. The “critical period for weed control” (CPWC) is defined as: A. The stage from seedling emergence to first true leaf B. The window when weeds cause irreversible yield loss if not controlled C. The period when herbicides are most phytotoxic to crops D. The time between two successive herbicide applications Answer: B
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Explanation: CPWC is the timeframe during which weed competition must be avoided to prevent yield loss. Question 57. Which of the following is a primary advantage of using a split‑application fertilizer program? A. Reduces need for soil testing B. Matches nutrient supply with crop demand, improving use efficiency C. Guarantees uniform nutrient distribution regardless of soil type D. Eliminates the risk of fertilizer burn Answer: B Explanation: Splitting applications aligns nutrient availability with crop growth stages. Question 58. The term “soil‑structure stability” is most directly affected by: A. Soil temperature fluctuations B. Sodium adsorption ratio (SAR) C. Soil organic carbon content D. Soil color Answer: B Explanation: High SAR leads to dispersion of clay particles, degrading structure. Question 59. Which of the following is a key indicator of water stress in a wheat crop? A. Increased leaf rolling and wilting B. Dark green leaf coloration C. Excessive tillering D. Early flowering
