WAEC Agricultural Science 1999 past questions

Checked by the Skolra question team · Last updated 23 October 2026

Ten questions from the 1999 WAEC Agricultural Science paper, with answers and explanations. We hold 55 questions from this paper, and the Skolra app has all of them.

WAEC Agricultural Science 1999 questions and answers

1. 1.If urea fertilizer contains 46% nitrogen, calculate the amount of nitrogen in a 25 kg bag of fertilizer.
   1. A
      1.15 kg
   2. B
      11.5 kg
      Correct
   3. C
      12.5 kg
   4. D
      23 kg
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   Answer: B

   11.5 kg is correct.

   Urea contains 46% nitrogen by weight. To find the actual amount of nitrogen in a 25 kg bag, multiply the percentage (as a decimal) by the total weight:

   Nitrogen = 46% × 25 kg = 0.46 × 25 kg = 11.5 kg

   A candidate who rounds 46% up to 50% for "easy" mental math gets 12.5 kg, which overstates the nitrogen content — always use the exact percentage given.

2. 2.The method of irrigation suitable for use on a steep slope is
   1. A
      Furrow irrigation
   2. B
      Basin irrigation
   3. C
      Sprinkler irrigation
      Correct
   4. D
      Border irrigation
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   Answer: C

   Sprinkler irrigation is the method suitable for a steep slope. In sprinkler irrigation, water is pumped under pressure through pipes and sprayed into the air in form of a mist or small droplets, much like rainfall, falling evenly over the crops. Because the water is delivered through the air rather than being made to flow over the soil surface, the method does not depend on the natural slope or shape of the land, and the land does not need to be levelled before use.

3. 3.An important farm machine used for coupling many implements is
   1. A
      Plough
   2. B
      Harrow
   3. C
      Tractor
      Correct
   4. D
      Ridger
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   Answer: C

   The tractor is correct. A tractor is the farm machine that supplies power and has a hitching system (drawbar, three-point linkage and power take-off, PTO) that allows it to be coupled to many different implements one after another — a plough for primary tillage, a harrow for breaking clods, a ridger for making ridges, a planter, a trailer, and so on. Without the tractor's coupling points, none of these implements can be powered or pulled across the field.

   So the farm machine used for coupling many implements together is the tractor.

4. 4.The characteristic symptoms of mosaic disease of crops is usually observed on
   1. A
      the stem
   2. B
      the flowers
   3. C
      the leaves
      Correct
   4. D
      the roots
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   Answer: C

   Mosaic disease is a viral disease that attacks crops such as cassava, tobacco, cowpea and cucurbits. Its name comes from the pattern it produces: patches of light green, yellow and dark green arranged like a mosaic (a tiled pattern).

5. 5.Which of the following methods of agricultural extension aims at reaching a large number of farmers at the same time?
   1. A
      Result demonstration method
   2. B
      Group method
   3. C
      Individual method
   4. D
      Mass method
      Correct
   Show answerHide answer

   Answer: D

   The mass method is correct. Agricultural extension methods are grouped into three broad categories based on how many farmers they reach at once: individual, group, and mass methods. The mass method uses channels like radio, television, newspapers, bulletins, posters and agricultural shows/campaigns, which carry the same information to a very large, often scattered, audience of farmers simultaneously. This is why it is the extension officer's choice when the goal is to spread a message widely and quickly, such as announcing a new fertiliser subsidy or warning about a pest outbreak.

6. 6.The effects of practicing crop rotation include the following except
   1. A
      Control of pests and diseases
   2. B
      Soil exhaustion
      Correct
   3. C
      Control of weeds
   4. D
      Maintenance of soil fertility
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   Answer: B

   Crop rotation means growing different crops in a planned sequence on the same piece of land, season after season, instead of growing the same crop continuously.

7. 7.The main source of power for subsistence equipment is
   1. A
      Tractors and other mechanised engines
   2. B
      Human labour
      Correct
   3. C
      Draught animals such as oxen and horses
   4. D
      Wind and water power
   Show answerHide answer

   Answer: B

   Human labour is the main source of power for subsistence equipment.

   Subsistence farming is small-scale farming done mainly to feed the farmer's family, with little money to spend on machinery or even animal traction. The farmer therefore depends on his own muscle power (and that of family members) to operate simple tools such as the hoe, cutlass, axe and sickle for clearing, tilling, planting, weeding and harvesting.

8. 8.Methods of preserving fish include the following except
   1. A
      Salting
   2. B
      Smoking
   3. C
      Boiling
      Correct
   4. D
      Drying
   Show answerHide answer

   Answer: C

   Boiling is the odd one out. Boiling is a method of cooking fish for immediate eating, not a method of preserving it — once boiled fish cools down, it still spoils within hours because the moisture content that supports bacterial and microbial growth has not been removed or controlled.

   So a candidate who picks smoking, drying, or salting has mistaken a real preservation technique for the exception; the correct exception is boiling, since it only cooks the fish for the moment rather than keeping it from spoiling afterwards.

9. 9.Food shortage can be minimized by
   1. A
      Cropping the same piece of land continuously without a fallow period
   2. B
      Clearing new farmland by bush burning before each planting season
   3. C
      Practising irrigation farming to allow crop production all year round
      Correct
   4. D
      Growing only one type of crop on all available farmland every season
   Show answerHide answer

   Answer: C

   Irrigation farming is the correct way to minimize food shortage. In Nigeria, most arable farming depends on rainfall, so production drops sharply in the dry season. By supplying water artificially (irrigation), farmers can grow crops throughout the year instead of only during the rains, which steadily increases total food supply and reduces shortage.

10. 10.The tree species commonly planted for pulpwood is
    1. A
       Gmelina
       Correct
    2. B
       Teak
    3. C
       Iroko
    4. D
       Obeche
    Show answerHide answer

    Answer: A

    Gmelina (Gmelina arborea) is the tree species commonly planted in Nigeria specifically for pulpwood. It is fast-growing, has a straight stem and light wood fibre that pulps easily for paper making, which is why it was chosen for Nigeria's forest plantations that feed paper mills such as the ones at Iwopin (Ogun State) and Jebba.

The questions come from past JAMB, WAEC and NECO papers. We use software to help write the answer options and explanations, and every answer is checked twice before it goes on the site. How we check

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