WAEC SSCE - Agricultural Science - 2020 (Essay)

Answer Details

(a) Completed disease table:

(b) Five advantages of the battery cage system in poultry production:

1. Efficient use of space through high stocking density.
2. Eggs are clean and easily collected with little breakage.
3. Diseases and parasites are easily controlled since birds do not touch their droppings.
4. Individual birds are easily observed and poor layers are readily culled.
5. Feed wastage, broodiness and cannibalism are greatly reduced.

(c) Five reasons why some extension programmes are not successful in West Africa:

1. Inadequate funding of extension services.
2. Too few and poorly trained extension agents (a low agent-to-farmer ratio).
3. Poor roads, transport and communication infrastructure.
4. Illiteracy of farmers and their resistance to change.
5. Inconsistent government policies and weak research-extension linkage.

Answer Details

(a) Life cycle of the variegated grasshopper (Zonocerus variegatus)

The variegated grasshopper undergoes incomplete metamorphosis with three stages:

1. Egg stage: The female lays batches of eggs in egg pods buried in moist soil. The eggs remain in the soil and hatch after the dry season, usually with the onset of rains.
2. Nymph stage: The hatched young ones (nymphs) resemble the adults but are smaller and wingless. They feed on vegetation and pass through several moults (instars), gradually developing wing buds.
3. Adult stage: After the final moult the nymph becomes a fully winged adult with the characteristic variegated (multi-coloured) body. Adults mate, and the females lay eggs, so the cycle continues.

(b) Five ways diseases are spread on crop farms

• By insect vectors (for example aphids and whiteflies transmitting viruses).
• Through infected planting materials such as seeds, cuttings and tubers.
• By wind carrying fungal spores.
• By irrigation and rain water carrying pathogens from plant to plant.
• Through contaminated farm tools, implements and the hands of farm workers.

(Also by soil harbouring pathogens, and by man and animals moving through the field.)

(c) Six characteristics of a good layer

• It has a bright red, well developed comb and wattles.
• It has a soft, large and moist vent.
• It has a wide space (three to four fingers) between the pelvic bones.
• It is alert, active and has bright eyes.
• It has a soft, pliable and expanded abdomen.
• It has bleached (pale) shanks and beak, showing that pigment has gone into egg production, and it lays many large eggs.

Answer Details

(a) Two solutions to each problem of agricultural development in Africa:

(i) Poor transportation:

• Construct and maintain good rural/feeder roads linking farms to markets.
• Provide adequate means of transport such as vehicles, and develop railways and waterways.

(ii) Environmental degradation:

• Practise soil-conservation measures such as afforestation, cover cropping, terracing and controlled grazing.
• Avoid bush burning and enforce laws against deforestation and pollution.

(iii) Use of crude farm tools:

• Introduce and subsidise modern machines and improved implements for farmers.
• Train farmers in the use and maintenance of modern equipment and provide credit to buy them.

(b) Three precautions when using each type of farm power:

(i) Animal power:

• Do not overload or overwork the animals; give them rest.
• Feed and water them well and keep them healthy.
• Use well-fitting harnesses to avoid injuring the animals.

(ii) Electrical power:

• Avoid touching electrical wires/switches with wet hands.
• Repair faulty wiring and insulate/earth all connections properly.
• Switch off the mains before servicing equipment and avoid overloading circuits.

(c) Six reasons for maintaining farm tools and implements:

• To make them last longer (increase durability).
• To keep them in good working condition and efficient.
• To prevent rust and damage.
• To reduce the cost of frequent repair and replacement.
• To prevent accidents/injury during use.
• To ensure good quality of work and save time and labour.

Answer Details

(a)

(i) Soil texture refers to the proportion of sand, silt, and clay particles in the soil. The texture affects the soil's water-holding capacity, aeration, and nutrient retention capacity.

(ii) Soil profile refers to the vertical section of soil, showing different layers or horizons, with varying physical and chemical properties. These layers are formed over time due to weathering and biological processes and are important for understanding the soil's characteristics and potential for crop production.

(b)

(i) Three advantages of grafting are:

• Increased resistance to pests and diseases
• Improved plant vigor and yield
• Ability to grow different varieties on the same rootstock for efficient use of space and resources.

(ii) Two crops that could be propagated by grafting are fruit trees (such as apples, peaches, and plums) and grapevines.

(c) Four cultural practices that could be used to replenish nutrients in the soil are:

• Crop rotation: growing different crops in sequence to reduce soil depletion of specific nutrients
• Cover cropping: planting non-cash crops to add organic matter to the soil and fix nitrogen
• Green manuring: intentionally growing and then plowing under specific crops to improve soil fertility
• Addition of organic matter: applying compost, manure, or other organic materials to the soil to improve its nutrient content and structure.

(d) Four measures that could be adopted by farmers to control pests in grain stores are:

• Proper storage: using clean and dry containers with tight-fitting lids to prevent entry of pests
• Regular cleaning: sweeping, vacuuming, and removing debris to eliminate hiding places for pests
• Fumigation: using chemicals to kill pests in stored grains
• Monitoring: regularly checking for signs of pest infestation and taking immediate action to prevent further spread.

Answer Details

(a) Cultivation of Citrus spp

(i) Method of propagation: Citrus is propagated both sexually (by seeds) and, more commonly for commercial orchards, vegetatively by budding (T or shield budding) onto a resistant rootstock such as rough lemon or sour orange. Budding is preferred because it keeps the desirable qualities of the parent, ensures early fruiting and gives uniform trees.

(ii) Spacing in the field: Citrus is planted at about 6 m x 6 m to 8 m x 8 m (approximately 150 to 280 trees per hectare), depending on the species and soil fertility. Wide spacing allows light penetration, air circulation and easy movement for spraying and harvesting.

(iii) Nursery practices:

• Prepare fine, well drained nursery beds and sow rootstock seeds.
• Provide partial shade and water regularly.
• Weed, and apply fertilizer to raise vigorous seedlings.
• Bud the seedlings when the stems reach pencil thickness.
• Harden off seedlings before transplanting to the field.

(iv) Pests: Aphids, citrus leaf miner, fruit flies, mealy bugs, scale insects and citrus psyllid.

(v) Diseases: Citrus canker, gummosis (foot rot caused by Phytophthora), citrus greening (HLB), tristeza virus and sooty mould.

(b) Definitions

(i) Surface irrigation: The application of water to farmland by allowing it to flow over the soil surface by gravity, for example through furrows, basins or borders, so that it infiltrates into the root zone.

(ii) Surface drainage: The removal of excess water from the top of the land surface by means of open channels, ditches or graded slopes so that waterlogging is prevented.

(c) Advantages

(i) Surface irrigation:

• It is cheap and simple, requiring little equipment or technical skill.
• It does not require pumping energy where gravity flow is available.
• It can cover large areas and helps leach out harmful salts from the soil.

(ii) Surface drainage:

• It removes excess water and prevents waterlogging, improving soil aeration.
• It reduces soil erosion and the incidence of water-borne diseases.
• It allows earlier cultivation and prevents root rot, improving crop yield.

Answer Details

(a)(i) Area of the rectangular farmland

Area of a rectangle = length x breadth. The two measurements must first be in the same unit. Converting the length to kilometres, length = 0.2 km and breadth = 2,200 km.

\[ \text{Area} = 0.2\,\text{km} \times 2{,}200\,\text{km} = 440\,\text{km}^2 \]

(If the breadth is taken as 2,200 m, then converting length 0.2 km = 200 m gives Area = \(200\,\text{m} \times 2{,}200\,\text{m} = 440{,}000\,\text{m}^2 = 44\ \text{hectares}\). The key principle is to keep both dimensions in the same unit before multiplying.)

(a)(ii) Two importance of a balance sheet to a farm manager

• It shows the financial position (assets, liabilities and net worth) of the farm business at a particular date.
• It helps the manager to obtain credit or loans, since lenders assess the farm's solvency from it, and it guides sound financial planning and decision making.

(b) Five sources of agricultural loans in West Africa

• Commercial banks.
• Agricultural development banks (for example the Bank of Agriculture in Nigeria).
• Cooperative societies and thrift/credit unions.
• Government agencies and special credit schemes.
• Money lenders, friends and relatives.

(c) Three reasons wood shavings are preferred to sawdust on a deep litter floor

• Wood shavings absorb moisture well yet remain loose and do not cake, keeping the litter dry.
• Sawdust is fine and dusty and can be eaten by the birds or inhaled, causing respiratory problems and impaction; shavings avoid this.
• Wood shavings allow better aeration and are easier to turn and manage, reducing dampness, ammonia and disease.