WAEC SSCE - Agricultural Science - 1989 (Essay)

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(a) Weathering is the process by which rocks and minerals are broken down into smaller pieces or dissolved by physical, chemical or biological processes, in response to the conditions of the environment in which they exist.

(b) The three processes involved in rock weathering are:

1. Mechanical or physical weathering: This process involves the physical breakdown of rocks into smaller pieces without changing their chemical composition. Examples of mechanical weathering include freeze-thaw cycles, root wedging, abrasion, and exfoliation.
2. Chemical weathering: This process involves the chemical breakdown of rocks and minerals by the action of water, air, and other chemicals. Examples of chemical weathering include oxidation, hydrolysis, carbonation, and acid rain.
3. Biological weathering: This process involves the breakdown of rocks and minerals by the action of living organisms such as plants, animals, and microorganisms. Examples of biological weathering include root penetration, burrowing by animals, and decay by microorganisms.

(c) The agents of mechanical weathering are physical forces such as temperature changes, wind, water, and ice. For example, freeze-thaw cycles occur when water freezes in rock crevices and then expands as it turns into ice, causing the rock to crack and break apart.

The agents of chemical weathering are chemical compounds such as water, oxygen, carbon dioxide, and acids. For example, carbon dioxide in the air combines with water to form carbonic acid, which can dissolve minerals in rocks such as limestone, leading to their erosion and breakdown over time. Another example is acid rain, which results from the combination of rainwater with pollutants such as sulfur dioxide and nitrogen oxides, leading to the corrosion and breakdown of rocks and other structures.

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(a) Stem borers of cereal: Stem borers are a group of insects that cause significant economic losses to cereal crops such as maize, rice, and sorghum. They bore into the stems of these plants and feed on the vascular tissues, causing stunting, wilting, and even death of the plants. This can result in reduced yields and quality of the affected crops. Control measures include the use of resistant varieties, cultural practices such as crop rotation, and the application of insecticides.

(b) Grain weevils of stored produce: Grain weevils are a common pest of stored grains such as maize, rice, and wheat. They feed on the kernels of these grains, reducing their quality and making them unsuitable for consumption or sale. Control measures include proper storage techniques such as drying and fumigation, as well as the use of insecticides.

(c) Cotton stainer: Cotton stainers are insects that feed on cotton plants and stain the fibers with a reddish-brown color, reducing the value and marketability of the cotton. They also reduce yields by damaging the developing bolls. Control measures include the use of resistant varieties, cultural practices such as crop rotation and weed control, and the application of insecticides.

(d) Cassava mealy bug: Cassava mealy bug is a serious pest of cassava, a staple crop in many African countries. It feeds on the leaves and stems of cassava, causing stunting and reduced yields. Control measures include the use of resistant varieties, cultural practices such as intercropping with legumes, and the application of insecticides. In addition, the introduction of natural enemies such as parasitic wasps has been successful in controlling the pest in some areas.

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Land tenure refers to the system of rules and regulations that govern the use, ownership, and transfer of land. In Nigeria, there are four major systems of land tenure, which are:

1. Traditional/Communal land tenure: This system of land tenure is based on the communal ownership of land by families or communities. It is characterized by the absence of private ownership and the existence of customary rules and regulations governing land use, transfer, and inheritance.
2. Individual land tenure: This system of land tenure involves the ownership of land by individuals, who have exclusive rights to use, transfer, and inherit the land. The land may be acquired through purchase, inheritance, or allocation by the government.
3. Leasehold land tenure: This system of land tenure involves the leasing of land for a specified period of time, usually between 50-99 years. The lessee has exclusive rights to use and benefit from the land, but ownership remains with the lessor.
4. Government land tenure: This system of land tenure involves the ownership and control of land by the government. The government may allocate land to individuals or organizations for specific purposes such as agriculture, housing, or industrial development.

Each system of land tenure has its advantages and disadvantages. For instance, traditional/communal land tenure promotes social cohesion and community development, but may not be conducive to individual investment and economic growth. Individual land tenure, on the other hand, encourages individual investment and economic growth, but may lead to land speculation and inequality. Leasehold land tenure provides a middle ground between individual and communal ownership, but may limit long-term investment and development. Government land tenure can facilitate planned development and control over land use, but may be prone to corruption and misuse of power.

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(a) Farm records refer to the systematic recording of important information related to farming activities, such as crop production, livestock management, and financial transactions. Farm accounts, on the other hand, refer to the systematic recording and management of financial transactions related to farm operations.

(b) There are several reasons for keeping farm records and accounts, including:

1. Planning: Farm records help farmers to plan their activities, such as deciding which crops to plant or when to breed their animals.
2. Monitoring performance: Farm records allow farmers to monitor the performance of their crops and animals over time, which can help them to make informed decisions about how to improve their operations.
3. Budgeting: Farm accounts help farmers to create and manage budgets for their operations, which can help them to control costs and improve profitability.
4. Tax reporting: Farm accounts are important for tax reporting purposes, as they provide the necessary financial information for filing tax returns.
5. Obtaining credit: Farm records and accounts are often required when applying for loans or other forms of credit.
6. Evaluating profitability: By keeping detailed records of their expenses and income, farmers can evaluate the profitability of their operations and identify areas for improvement.
7. Compliance: Farm records and accounts may be required to comply with regulations related to environmental and food safety, as well as labor and employment laws.

Overall, keeping accurate and up-to-date farm records and accounts is essential for effective farm management and decision-making.

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(a) Five factors required for establishing a fish pond are:

1. Location: A suitable location for a fish pond should be chosen, which has adequate water supply, good soil quality, and is free from pollution.
2. Topography: The land should be properly leveled to prevent water from accumulating in certain areas and to allow for even distribution of water in the pond.
3. Water supply: An adequate and reliable source of water is necessary for the fish pond. This can be from a natural spring, stream, or well.
4. Pond design: The pond should be designed in a way that allows for easy water circulation, adequate depth for fish growth, and proper aeration.
5. Fish species: The type of fish to be reared should be chosen based on the water conditions, climate, and market demand.

(b) Six management practices for maintaining high fish yield are:

1. Feeding: Proper feeding of the fish is essential for growth and development. The type of feed and frequency of feeding should be based on the fish species and size.
2. Water quality: Maintaining good water quality is important for the health of the fish. Regular water testing and monitoring should be done to ensure the pH level, temperature, and oxygen levels are optimal.
3. Harvesting: Fish should be harvested at the right time to avoid over-crowding and to ensure maximum yield. Harvesting should be done carefully to avoid stress and injury to the fish.
4. Disease control: Proper sanitation, quarantine procedures, and regular health checks should be done to prevent and control disease outbreaks.
5. Pond maintenance: Regular pond maintenance, including removing debris and dead fish, and repairing leaks and damaged equipment, is important for maintaining a healthy environment for the fish.
6. Record keeping: Keeping accurate records of feed usage, water quality, and fish growth is important for tracking performance and identifying areas for improvement.

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(a) Work animals: Animals such as oxen, horses, and donkeys have been used as a source of farm power for centuries. They can be used for plowing, harrowing, planting, and transportation of farm produce. The advantage of work animals is that they do not require fuel and can be fed on farm-grown crops. However, they require proper care and maintenance, and their use can be limited by their physical strength and endurance.

(b) Machine engines: Machine engines such as tractors, combine harvesters, and tillers are popular sources of farm power in modern agriculture. They are efficient, reliable, and can perform a wide range of tasks. The engines are powered by diesel, gasoline, or electricity. Their advantages include increased productivity, reduced labor requirements, and faster completion of farm tasks. However, they require significant capital investment and skilled operators to maintain them.

(c) Water: Water can be used as a source of farm power through the use of watermills and hydroelectric generators. Watermills can be used to grind grains and pump water for irrigation. Hydroelectric generators can provide electricity for farm operations. The advantage of water power is that it is renewable and does not require fuel. However, it is limited by the availability of water sources and the topography of the farm.

(d) Sun: Solar power can be used to provide electricity for farm operations. Solar panels can be used to power lights, pumps, and other electrical equipment. The advantage of solar power is that it is renewable and does not produce greenhouse gas emissions. However, it requires significant capital investment and is limited by the availability of sunlight.

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(a) Selective exploration refers to the process of extracting resources from an area by selectively removing only certain trees or other natural resources, while leaving the rest of the area undisturbed. This is commonly used in forestry and mining operations to minimize environmental damage and ensure sustainability.

(b) Deforestation is the process of clearing forests and trees on a large scale, usually to make room for agriculture, urbanization, or other forms of human development. Deforestation has significant environmental impacts, including soil erosion, loss of biodiversity, and climate change.

(c) Regeneration refers to the natural regrowth and recovery of an ecosystem after it has been damaged or disturbed. This can happen after a natural disaster, such as a forest fire or hurricane, or as a result of human activities like logging or mining. Regeneration is important for maintaining ecosystem health and biodiversity.

(d) Afforestation is the process of planting trees in an area where there was no previous forest cover. Afforestation can help combat climate change by sequestering carbon dioxide from the atmosphere, as well as provide habitat for wildlife, protect soil from erosion, and improve air and water quality.

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(a) Agricultural extension refers to the process of transferring knowledge and technology related to agriculture from research centers to farmers. It involves the use of various methods and techniques to teach farmers how to adopt new and improved farming practices, technologies, and innovations.

(b) The following methods can be used to disseminate new ideas and techniques to farmers in Nigeria:

1. Mass media: This method involves the use of electronic and print media to reach a large number of farmers. For instance, radio and television programs can be used to disseminate information on new farming techniques, market prices, weather forecasts, and government policies. Similarly, agricultural magazines and newspapers can be used to provide information on farming practices and innovations.
2. Individual method: This method involves one-on-one interactions between agricultural extension workers and farmers. It involves visiting farms to assess the problems faced by farmers and to provide advice on how to solve them. The method is effective in situations where farmers are scattered across a wide area, and it helps to provide personalized attention to each farmer's needs.
3. Group method: This method involves organizing farmers into groups or associations, and then training them collectively on new farming techniques and innovations. The method is effective in situations where farmers are concentrated in a particular area. It allows for the exchange of ideas and experiences among farmers, which can enhance learning and adoption of new techniques. Group method can also create a platform for collective bargaining and accessing credit facilities.

In conclusion, agricultural extension is crucial in disseminating new ideas and techniques to farmers in Nigeria. The use of various methods and techniques such as mass media, individual method, and group method can enhance the effectiveness of agricultural extension services.

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a) Irrigation and drainage are two distinct processes in agriculture. Irrigation is the process of applying water to plants through various methods to supplement natural rainfall and ensure optimal plant growth and yield. On the other hand, drainage is the process of removing excess water from the soil or land to prevent waterlogging, soil salinity, and other problems that can lead to poor plant growth.

b) There are several systems of irrigation and drainage, and some of them are:

Systems of Irrigation:

1. Flood Irrigation: In this system, water is allowed to flood the entire field, and it is left to infiltrate the soil by gravity. It is a traditional and less efficient method of irrigation.
2. Sprinkler Irrigation: This system involves the use of sprinklers to distribute water on the plant leaves or over the field. Water is delivered to the plants in a spray-like manner, which simulates rainfall. It is suitable for areas with high temperatures and low humidity.
3. Drip Irrigation: In this system, water is applied slowly and directly to the root zone of plants. Water is delivered to the plants through a network of pipes and emitters that release water in droplets. It is a highly efficient irrigation method that saves water and energy.
4. Center Pivot Irrigation: This is a mechanized irrigation system that involves the use of a large sprinkler that rotates around a pivot point. Water is sprayed over the field as the sprinkler moves in a circular pattern. It is ideal for large, flat fields.

Systems of Drainage:

1. Surface Drainage: This system involves the use of surface channels or ditches to remove excess water from the land surface. It is useful in flat areas with poor drainage.
2. Subsurface Drainage: In this system, pipes or drain tiles are installed beneath the soil surface to remove excess water from the soil profile. It is useful in areas with high water tables and heavy soils that are prone to waterlogging.

In summary, irrigation involves the application of water to plants, while drainage involves the removal of excess water from the soil. Flood, sprinkler, drip, and center pivot irrigation are some of the systems of irrigation, while surface and subsurface drainage are some of the systems of drainage.

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(a) Causal organism: Rinderpest is caused by a virus called the rinderpest virus, which belongs to the Paramyxoviridae family.

(b) Transmission: The virus is highly contagious and is transmitted through contact with infected animals, their bodily fluids or excretions, and contaminated equipment or surroundings.

(c) Symptoms: Rinderpest has an incubation period of about 3-9 days, after which the animal starts to exhibit symptoms such as fever, loss of appetite, nasal and ocular discharges, diarrhea, and severe dehydration. The animal may also develop sores in the mouth and on the skin. In the later stages of the disease, the animal may show neurological signs such as paralysis and convulsions.

(d) Effects and economic importance: Rinderpest is a highly fatal disease that can wipe out entire herds of cattle, buffalo, and other cloven-hoofed animals. It has caused devastating losses in the past, leading to famine and poverty in many regions of the world. The disease has also had a significant impact on the economies of affected countries, reducing the availability of meat, milk, and draft power.

(e) Control: The most effective way to control rinderpest is through vaccination. Mass vaccination campaigns have been successful in eradicating the disease from many parts of the world. Other control measures include quarantine of infected animals, movement restrictions, and disinfection of contaminated equipment and surroundings.