JAMB and WAEC Agricultural Science questions: Soil fertility, manures and fertilisers

43 questions with answers and explanations. Tap an option to check yourself.

1. Question 21· Soil fertility, manures and fertilisers· WAEC

   Crop rotation helps to maintain soil fertility by

   • Agrowing one crop every year
   • Bgrowing crops with different nutrient needs in sequence
   • Cburning the farm
   • Dremoving all residues

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   Explanation and discussion

2. Question 22· Soil fertility, manures and fertilisers· WAEC

   Leaching reduces soil fertility by

   • Aincreasing organic matter
   • Badding nutrients
   • Cwashing nutrients down beyond the reach of roots
   • Dimproving soil structure

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3. Question 23· Soil fertility, manures and fertilisers· JAMB

   An NPK fertiliser labelled 20:10:10 contains

   • A20% nitrogen, 10% P₂O₅ and 10% K₂O
   • B20% potassium
   • Cequal NPK
   • Dno nitrogen

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4. Question 24· Soil fertility, manures and fertilisers· JAMB

   The conversion of ammonium compounds to nitrates by soil bacteria is

   • Anitrification
   • Bdenitrification
   • Cnitrogen fixation
   • Dammonification

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5. Question 25· Soil fertility, manures and fertilisers· JAMB

   Leguminous crops improve soil fertility by

   • Aremoving nitrogen
   • Bfixing atmospheric nitrogen through root nodule bacteria
   • Cadding potassium only
   • Draising soil temperature

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6. Question 26· Soil fertility, manures and fertilisers· JAMB

   Leaching is the

   • Aburning of vegetation
   • Baddition of nutrients
   • Cwashing down of soluble nutrients below the root zone
   • Dcompaction of soil

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   Explanation and discussion

7. Question 27· Soil fertility, manures and fertilisers· WAEC

   Which practice helps to maintain soil fertility?

   • Abush burning
   • Bcontinuous cropping of maize
   • Ccrop rotation that includes legumes
   • Dovergrazing

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8. Question 28· Soil fertility, manures and fertilisers· JAMB

   Phosphorus is needed by crops mainly for

   • Agreen leaf colour only
   • Broot development and seed formation
   • Cabsorbing water
   • Ddrought resistance only

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9. Question 29· Soil fertility, manures and fertilisers· WAEC

   A farmer applies 100 kg of NPK 15-15-15 fertiliser. How much nitrogen does it supply?

   • A5 kg
   • B45 kg
   • C100 kg
   • D15 kg

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10. Question 30· Soil fertility, manures and fertilisers· JAMB

    Deficiency of nitrogen in crops is shown by

    • Apurple leaves only
    • Byellowing of older leaves and stunted growth
    • Cleaf scorch at the margins only
    • Dexcessive vegetative growth

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11. Question 31· Soil fertility, manures and fertilisers· JAMB

    Potassium deficiency in plants is shown by

    • Adeep roots
    • Bdark green leaves
    • Cfast growth
    • Dscorching of leaf margins

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12. Question 32· Soil fertility, manures and fertilisers· WAEC

    Adding lime to an acidic soil raises its

    • Aorganic matter
    • Bsalt content
    • CpH
    • Dnitrogen content

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13. Question 33· Soil fertility, manures and fertilisers· JAMB

    Potassium deficiency in crops shows mainly as

    • Ascorching of leaf margins
    • Bpurple colouring of leaves
    • Cstunted roots only
    • Ddark green leaves

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14. Question 34· Soil fertility, manures and fertilisers· WAEC

    Muriate of potash supplies

    • Apotassium
    • Bnitrogen
    • Cphosphorus
    • Dsulphur

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15. Question 35· Soil fertility, manures and fertilisers· JAMB

    Which of these fertilisers supplies only nitrogen?

    • Asingle superphosphate
    • Burea
    • Cmuriate of potash
    • DNPK 20:10:10

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16. Question 36· Soil fertility, manures and fertilisers· WAEC

    Yellowing of older leaves (chlorosis) is a sign of

    • Atoo much sunlight
    • Bexcess water only
    • Cnitrogen deficiency
    • Dphosphorus excess

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17. Question 37· Soil fertility, manures and fertilisers· JAMB

    Which of these elements is a micronutrient?

    • Azinc
    • Bnitrogen
    • Cpotassium
    • Dcalcium

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18. Question 38· Soil fertility, manures and fertilisers· JAMB

    Yellowing of the older leaves of maize most likely shows a shortage of

    • Airon
    • Bcalcium
    • Cboron
    • Dnitrogen

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19. Question 39· Soil fertility, manures and fertilisers· WAEC

    Phosphorus deficiency in crops shows mainly as

    • Apoor root growth and purplish leaves
    • Byellowing of older leaves
    • Cscorched leaf margins
    • Dwhite spots on fruits

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20. Question 40· Soil fertility, manures and fertilisers· JAMB

    Rhizobium bacteria live in the root nodules of

    • Atubers
    • Bcereals
    • Clegumes
    • Dgrasses

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    Explanation and discussion