WAEC SSCE - Agricultural Science - 2012

Maelezo ya Majibu

Maelezo ya Majibu

To determine the number of pigs that can be housed in a pigsty measuring 5.0 m by 4.0 m, we need to calculate the total floor area of the pigsty. The area of the pigsty = Length x Width = 5.0 m x 4.0 m = 20.0 square meters To find the number of pigs that can be housed, we need to divide the total floor area of the pigsty by the floor space required for each pig. Number of pigs = Total area of pigsty / Floor space per pig = 20.0 m2 / 2.0 m2 per pig = 10 pigs Therefore, the correct option is 10.

Maelezo ya Majibu

A farm business makes a profit when the total revenue exceeds the total cost. This means that the income generated from selling the products or services is greater than the expenses incurred in producing them. In other words, the farm business is earning more money than it is spending. Profit is important for the sustainability and growth of a farm business, as it provides funds for reinvestment in the business, expansion, and future development.

Maelezo ya Majibu

Citrus trees are usually propagated by budding. This is a vegetative propagation method where a bud of a selected variety is inserted into the bark of a rootstock. The bud then grows into a shoot which becomes the scion and the rootstock provides the root system. The use of budding ensures that the new trees have the same characteristics as the parent tree, and also allows for the production of disease-resistant trees. It is a common and effective method of citrus propagation in commercial agriculture.

Maelezo ya Majibu

The first activity to undertake before establishing a plantation is to survey the land. Surveying the land involves conducting a detailed analysis of the site where the plantation will be located. This is an essential step in the planning process as it helps to determine the suitability of the land for planting, and to identify any potential challenges or limitations that may impact the success of the plantation. The survey typically includes an assessment of the soil quality, topography, climate, and water availability. This information is used to determine the best crop to plant, as well as the most suitable planting method, fertilizer application, and irrigation system. By surveying the land, farmers are able to make informed decisions about how to develop the plantation and minimize the risks associated with crop failure or low yields. This can help to ensure the long-term viability and sustainability of the plantation, and maximize the returns on the investment.

Maelezo ya Majibu

Maelezo ya Majibu

The earthworm is important to the farmer because it helps to improve the soil in many ways. It helps to aerate the soil by creating tunnels, which allows oxygen and water to penetrate deep into the soil. The tunnels also provide a way for roots to grow deeper, making the plants more resistant to drought. Additionally, the earthworm eats organic matter and other microorganisms in the soil, breaking them down and turning them into nutrients that plants can use. This process helps to improve soil texture and structure, making it easier for plants to grow. Finally, the earthworm helps to check soil erosion by binding soil particles together, reducing the risk of soil being washed away by heavy rain.

Maelezo ya Majibu

The botanical name of groundnut is arachis hypogaea. Botanical names are a way to identify plants using a standardized system of names, which helps to avoid confusion caused by common names that can vary from region to region or even from person to person. The botanical name of a plant consists of two parts: the genus name, which is capitalized, and the species name, which is not capitalized. In this case, "arachis" is the genus name and "hypogaea" is the species name. Knowing the botanical name of a plant can help people communicate more effectively about it, as well as provide a more accurate way to identify it.

Maelezo ya Majibu

The price of a fixed asset at the end of its useful life is called the salvage value. This refers to the estimated amount of money that the asset can be sold for once it is no longer useful to the business. For example, if a company buys a truck for $50,000 and estimates that it will have a useful life of 10 years, at the end of the 10 years, the truck may be sold for its salvage value. This value is important for businesses to consider when they are deciding whether or not to invest in a fixed asset, as it can help them estimate the total cost of ownership over the asset's useful life. It is also important for accounting purposes, as it is used to calculate the depreciation expense for each year of the asset's useful life.

Maelezo ya Majibu

Marginal cost of production is defined as the increase in total cost as output is increased by one unit. In other words, it is the additional cost incurred by a firm when it produces one more unit of a good or service. This can include the cost of raw materials, labor, and any other variable costs associated with production. By calculating marginal cost, firms can make informed decisions about how much to produce, as they can compare the additional revenue generated by producing an additional unit with the additional cost of producing that unit. This can help firms optimize their production processes and maximize profits.

Maelezo ya Majibu

The correct answer is: I, II, and III are all used in selecting agricultural extension teaching methods. When selecting agricultural extension teaching methods, the time available for the program, the number of farmers involved, and the agricultural needs of the farmers are all important criteria. For example, if there is limited time available for the program, methods that are quick and easy to implement, such as demonstrations or group discussions, may be preferred. If a large number of farmers are involved, methods that can be scaled up easily, such as radio broadcasts or video presentations, may be preferred. And if the agricultural needs of the farmers are diverse, methods that can be tailored to specific needs, such as individual counseling or farm visits, may be preferred. Therefore, all three criteria are important in selecting the most effective agricultural extension teaching methods.

Maelezo ya Majibu

The correct answer is: I and II only. Mulching is a farming practice where organic or inorganic materials are placed on top of the soil surface. One of the advantages of mulching is that it helps to control weeds by depriving them of sunlight, which they need to grow. Mulching also helps to conserve soil moisture by reducing evaporation from the soil surface. This helps to maintain a steady supply of moisture for crops to grow. However, mulching does not increase soil temperature and does not directly affect soil pH.

Maelezo ya Majibu

The type of weed control involved when tilapia feeds on aquatic weeds is biological. This is because the control method involves the use of living organisms (tilapia fish) to naturally reduce the growth and spread of aquatic weeds in a water body. The tilapia fish feed on the weeds and thereby limit their growth, without the use of any chemical or mechanical means. This method is a sustainable and environmentally friendly approach to weed control in aquatic environments.

Maelezo ya Majibu

If an injured goat is bleeding without clotting, the goat is likely deficient in Vitamin K. Vitamin K is an important nutrient that helps the blood clot. When an injury occurs, the body needs to form a blood clot to stop the bleeding. Without enough Vitamin K, the blood will not clot properly and the bleeding will continue. This can be dangerous because the goat can lose too much blood and become very sick. Other vitamins like vitamin D, vitamin E and vitamin C are important for the body, but they don't play a direct role in blood clotting. Vitamin D helps the body absorb calcium and promotes bone health, vitamin E is an antioxidant that protects cells from damage, and vitamin C is important for immune function and collagen production. However, a deficiency in these vitamins would not directly cause bleeding without clotting.

Maelezo ya Majibu

The process where bacteria remove oxygen from nitrates in the soil, resulting in the loss of nitrogen from the soil, is known as denitrification. During denitrification, bacteria convert nitrate into nitrogen gas, which is then lost to the atmosphere. This can occur in soils that are saturated with water or have low oxygen levels, which creates an environment conducive to denitrifying bacteria. Denitrification can be problematic for agricultural systems because it results in a loss of nitrogen from the soil, which can lead to decreased crop yields and environmental pollution.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The correct answer is: I and III only. Rubber production involves coagulation, which is the process of solidifying liquid latex into a coagulated mass, and tapping, which is the process of collecting latex from the rubber tree through incisions made on the bark of the tree. Fermentation is not a process associated with rubber production, as it is used primarily in the production of some agricultural crops and beverages.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Government finances agriculture through various means to support farmers and promote food security. These include the reduction of tariffs on agricultural inputs, granting of subsidies to farmers, establishment of agricultural colleges, and the establishment of credit sources. However, one of the options is not a way government finances agriculture. In this case, the option is "except," which implies that it is not a way government finances agriculture. Therefore, the correct answer is that all of the options listed are ways that government finances agriculture, and there is no option that is not a way government finances agriculture.

Maelezo ya Majibu

Agricultural production in West Africa can be improved by several practices, including the use of modern farm implements, the application of proven agricultural research findings, and the supply of improved seeds and livestock to farmers. However, the legislation of communal land holding system is not a practice that can improve agricultural production in West Africa. In fact, communal land holding system can create challenges for farmers as it often involves multiple individuals or families sharing a single piece of land, making it difficult to implement modern farming practices or to make decisions about how to use the land. Additionally, communal land holding system can create disputes over land ownership or usage, which can lead to conflict and further hinder agricultural productivity. Therefore, while other practices can contribute to improving agricultural production in West Africa, the legislation of communal land holding system is not one of them.

Maelezo ya Majibu

The statement that is true about the effects of diseases on crops is that they lead to a reduction in the quality of products (I), a reduction in the photosynthetic ability (II), and a reduction in the yield of the produce (IV). Crop diseases can cause discoloration, spots, and other blemishes that lower the market value of the crop. They can also interfere with the plant's ability to perform photosynthesis, which reduces its growth and productivity. Moreover, some diseases can cause the plant to wither or die, which ultimately reduces the yield of the crop. While diseases may not necessarily increase the cost of production (III), they can still have a significant economic impact by reducing the quantity and quality of the produce. Therefore, the correct option is I, II, and IV only.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The crops that are useful to the soap-making industry are coconut and shea nut. Coconut oil is commonly used in soap-making due to its ability to create a rich, creamy lather and its moisturizing properties. Shea butter, which is derived from the shea nut, is also commonly used in soap-making due to its moisturizing and healing properties for the skin. Kolanut, on the other hand, is not typically used in soap-making. Therefore, the correct option is II and III only.

Maelezo ya Majibu

Striga spp. is a parasitic weed of sorghum. It is a serious threat to sorghum production in many parts of Africa, including West Africa. The weed attaches itself to the roots of sorghum and absorbs nutrients and water from the host plant, resulting in stunted growth, reduced yield, and even crop failure. It is important for farmers to manage Striga spp. through a combination of cultural practices, such as crop rotation and intercropping, and chemical control methods, such as the use of herbicides.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The term that is not associated with surface irrigation is "tile". Tile drainage is a type of subsurface drainage system used to remove excess water from the soil. The other three terms, basin, dyke, and furrow, are all related to surface irrigation. - Basin irrigation is a method where water is applied to a level or gently sloping field and allowed to pond, providing water to crops from the bottom up. - Dyke irrigation involves constructing small earthen embankments to create small basins in which crops are grown. - Furrow irrigation is a method where water is applied in small channels, or furrows, between crop rows to provide water to crops.

Maelezo ya Majibu

Fish ponds in arid areas should be deeper than those in the rain forests to prevent loss of fish through extreme temperatures. Arid areas have higher temperatures and lower humidity levels compared to rain forests, which can lead to high rates of evaporation and water loss from shallow ponds. By making the fish ponds deeper, the water can be stored at cooler temperatures, reducing the risk of heat stress and dehydration for the fish. This can promote healthy growth and survival of the fish in arid areas.

Maelezo ya Majibu

Pedigree selection in animal improvement is based on the performance of the ancestors. This means that animals are selected based on the performance of their parents, grandparents, and other ancestors. This is done in the belief that an animal's genetic potential for desirable traits can be inherited from its ancestors. Therefore, the selection of animals for breeding is based on the performance of their ancestors in terms of traits such as growth rate, milk production, meat quality, disease resistance, and other desirable characteristics. By selecting animals based on their pedigree, it is hoped that the desirable traits will be passed down to the next generation, resulting in improved performance of the offspring.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Fruits should be harvested at the appropriate time in order to ensure good quality produce. Harvesting fruits at the right time helps to maximize their flavor, texture, and nutritional content. If fruits are harvested too early or too late, their quality can be compromised, resulting in a loss of taste, texture, and nutrient value. Therefore, it is important to carefully monitor and determine the appropriate time for fruit harvesting to obtain high-quality produce.

Maelezo ya Majibu

Maelezo ya Majibu

The soil water that is readily available for absorption by plant roots is called capillary water. Capillary water is held in the soil by capillary forces, which are the forces that allow water to move through narrow spaces, such as the tiny spaces between soil particles. This type of water is easily accessed by plant roots and is essential for plant growth and survival. Gravitational water, on the other hand, is water that drains out of the soil due to gravity and is not available to plants. Hygroscopic water is water that is held tightly to soil particles and is also not available to plants. Superfluous water is excess water that can lead to waterlogging and soil erosion, and is also not available to plants. Therefore, capillary water is the type of soil water that is most important for plant growth and is readily available for absorption by plant roots.

Maelezo ya Majibu

The cost price of a farm equipment can be calculated using the straight-line method of depreciation. This method assumes that the value of the equipment decreases by an equal amount each year over its useful life. To calculate the cost price, we can use the formula: Cost price = Salvage value + Total depreciation The salvage value of the equipment is given as N500,000.00. The annual depreciation is given as N400,000.00, and the useful life is 10 years. Therefore, the total depreciation over the useful life of the equipment is: Total depreciation = Annual depreciation x Useful life Total depreciation = N400,000.00 x 10 Total depreciation = N4,000,000.00 Substituting the values into the formula, we get: Cost price = Salvage value + Total depreciation Cost price = N500,000.00 + N4,000,000.00 Cost price = N4,500,000.00 Therefore, the cost price of the farm equipment is N4,500,000.00.

Maelezo ya Majibu

Maelezo ya Majibu

Out of the given options, the only insect-pest that possesses biting and chewing mouthparts is the grasshopper. Biting and chewing mouthparts are specialized structures that enable an insect to cut, crush and grind solid food materials, such as plant tissues. Grasshoppers are known to cause significant damage to agricultural crops due to their feeding behavior. They feed on various types of plants, including grasses, cereals, vegetables, and fruits, by biting and chewing through the plant tissues.

Maelezo ya Majibu

Termites are useful in agriculture because they improve soil aeration. Termites are soil-dwelling insects that feed on organic matter, and in doing so, they create tunnels and burrows in the soil. These tunnels help to improve the structure of the soil and increase its permeability to water and air, which in turn enhances soil aeration. Improved soil aeration can have several benefits for agriculture. It can help to reduce soil compaction, which can improve root growth and nutrient uptake by plants. It can also improve water infiltration and retention, which can enhance crop productivity and reduce water runoff and erosion. While termites can sometimes be pests that cause damage to wooden structures, in agricultural systems they can be useful allies in promoting healthy soil ecosystems and improving crop productivity.

Maelezo ya Majibu

The feed conversion ratio (FCR) is the amount of feed consumed by an animal per unit of weight gain. To determine the FCR of the sheep, we divide the total amount of feed consumed by the amount of weight gained. In this case, the sheep gained 20 kg of weight after consuming 60 kg of feed. So, the FCR can be calculated as follows: FCR = Feed Consumed / Weight Gain FCR = 60 kg / 20 kg FCR = 3:1 Therefore, the feed conversion ratio of the sheep is 3:1. This means that the sheep consumed 3 kg of feed for every 1 kg of weight gain.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The symptom that is typical of louse infestation in livestock is itching of the body. Lice are ectoparasites that live on the skin and hair of livestock and feed on their blood. As they feed, they cause irritation and itching, which can lead to the animal rubbing and scratching against hard surfaces to relieve the itching. This can result in hair loss, skin lesions, and even secondary infections. While abdominal pain and profuse salivation are symptoms of other livestock diseases, oozing out of blood is not a common symptom of louse infestation.

Maelezo ya Majibu

One limitation to the practice of shifting cultivation in modern day agriculture is population pressure. This is because as population increases, there is less land available for shifting cultivation, and this can lead to overuse of the available land, which can cause soil degradation, reduced fertility and yield, and land-use conflicts. Additionally, population growth also leads to increased demand for food, which may require more intensive and sustainable agricultural practices to meet the demand.

Maelezo ya Majibu

Maelezo ya Majibu

(a) Four factors that affect the type of soil formed at a place [2 marks]

• Nature of the parent rock (parent material).
• Climate (rainfall and temperature).
• Living organisms (vegetation and soil organisms).
• Topography (relief) and length of time of soil formation.

(b) Uses of land [4 marks]

• (i) Two agricultural uses: for growing crops (crop cultivation) and for rearing/grazing livestock.
• (ii) Two non-agricultural uses: for building houses and roads (construction) and for mining/industrial and recreational purposes.

(c) Functions and deficiency symptoms of the nutrients [8 marks]

(d) Two ways soil structure is important in agriculture [2 marks]

• It determines soil aeration and drainage, which affect root respiration and water movement.
• It influences root penetration, water-holding capacity and the ease of tillage of the soil.

Maelezo ya Majibu

(a)(i) Incubation in poultry production [2 marks]

Incubation is the process of applying the correct warmth (heat), humidity and turning to fertile eggs for the period (about 21 days in the fowl) needed for the embryo to develop and hatch into a chick.

(a)(ii) Natural incubation: two advantages and two disadvantages [4 marks]

Advantages:

• It is cheap and needs no equipment or electricity.
• The mother hen provides warmth, turning and brooding, and cares for the chicks after hatching.

Disadvantages:

• Only a few eggs can be hatched at a time (limited number).
• The hen stops laying while brooding, and hatching cannot be planned/controlled; diseases and parasites may also be passed to the chicks.

(b) Four factors that affect pasture establishment in West Africa [4 marks]

• Rainfall/moisture availability.
• Soil type and fertility.
• Type/quality of seed and species of forage used.
• Method of land preparation and control of weeds, pests and bush fires (and grazing pressure).

(c) Causal organisms and symptoms of the diseases [6 marks]

Maelezo ya Majibu

(a) Forest reserve [2 marks]

A forest reserve is an area of forest land set aside and protected by law, mainly for the conservation and controlled production of forest resources, especially valuable tree species.

(b) Advantages of the taungya system of farming [4 marks]

(i) To farmers:

1. They obtain fertile land on which to grow food crops, often at little or no cost.
2. They obtain food, income and employment while the forest trees are still young.

(ii) To foresters:

1. Farmers weed and tend the young forest trees while cultivating their crops.
2. The cost of establishing and maintaining the forest plantation is reduced.

(c) Life cycle of yam beetle, Heteroligus metes [6 marks]

The yam beetle undergoes complete metamorphosis, as shown below.

1. The adult female beetle lays eggs in moist soil, usually under mulch, at the beginning of the yam-growing season.
2. The eggs hatch into larvae or grubs. The grubs feed mainly on decaying organic matter in the soil.
3. The larva moults through three larval stages and later changes into a pupa in the soil.
4. The pupa develops and moults into an adult beetle.
5. The adult beetle attacks yam tubers by boring into them and feeding on the tuber tissue. The female subsequently lays eggs and the cycle continues.

(d) Advantages of organic fertilizers over inorganic fertilizers [2 marks]

1. They add humus and improve soil structure and water-holding capacity.
2. They release nutrients gradually and are less likely to make the soil acidic.

(e) Varieties of oil palm [2 marks]

1. Dura
2. Tenera

Maelezo ya Majibu

(a) Loan and subsidy

• Loan: a repayable credit, in cash or kind, granted to a farmer for agricultural purposes. It may attract interest.
• Subsidy: non-repayable financial assistance, usually provided by government, to reduce part of the cost of farm inputs or services.

(b)(i) Supply

Supply is the quantity of a commodity which producers are willing and able to offer for sale at various prices over a given period of time.

(b)(ii) Supply curve for cocoa

Supply of cocoa (tonnes)	Price of cocoa (Le)
450	10,000
550	15,000
700	20,000
1,000	25,000
1,700	30,000

Plot the points (450, 10,000), (550, 15,000), (700, 20,000), (1,000, 25,000) and (1,700, 30,000), with supply on the horizontal axis and price on the vertical axis. Join the points to obtain the supply curve.

(b)(iii) Relationship between price and supply

The supply curve slopes upwards from left to right. This shows a direct relationship between price and quantity supplied: as the price of cocoa rises from Le10,000 to Le30,000, quantity supplied rises from 450 tonnes to 1,700 tonnes. Conversely, a lower price leads to a lower quantity supplied.

(c) Farm and home visits in agricultural extension

Advantages

1. The extension worker obtains first-hand knowledge of the farmer's farm and the actual problems faced.
2. It promotes personal contact, goodwill, confidence and mutual trust between the farmer and the extension worker.

Disadvantages

1. It is expensive and time-consuming, especially where farms are widely scattered.
2. Only a few farmers can be reached at a time.

(d) Characteristics of agricultural produce in marketing

1. Perishability: many agricultural products spoil rapidly after harvest.
2. Seasonality: production is seasonal, causing fluctuations in supply and price.
3. Bulkiness: many products are bulky and costly to transport and store.

Maelezo ya Majibu

(a) Communal land tenure system [2 marks]

Communal land tenure is a system of land ownership in which land belongs to the whole community (village or family) as a group, and individual members are only given the right to use portions of it, but no single member owns the land outright.

(b) Two objectives of each development programme [6 marks]

• (i) Farm settlement schemes: to settle and employ young school-leavers and unemployed people in modern farming; and to increase agricultural production and demonstrate improved farming methods.
• (ii) River basin authorities: to provide water for irrigation so that farming can go on all year round; and to control flooding and provide water for domestic, fishing and hydro-electric use.
• (iii) Agricultural development projects (ADPs): to provide extension services and improved inputs to farmers; and to construct rural infrastructure (feeder roads, dams, markets) that boosts food production.

(c)(i) Farm machinery versus farm implements [2 marks]

Farm machinery are engine-powered (self-propelled or motorised) equipment that generate their own power to do farm work, whereas farm implements are the simpler, non-powered tools/attachments that either do work by hand or are coupled to and drawn by a source of power such as a tractor.

(c)(ii) Six examples of each [6 marks]

Farm machinery: tractor, combine harvester, power tiller, milking machine, water pump, sheller/thresher.

Farm implements: plough, harrow, ridger, planter, cutlass, hoe.

Maelezo ya Majibu

(a) Subsistence agriculture [2 marks]

Subsistence agriculture is a type of farming in which the farmer produces crops and livestock mainly to feed himself and his family, with little or nothing left over for sale.

(b) Interdependence of agriculture and industry [6 marks]

• (i) Tools, implements and machinery industries: Agriculture depends on these industries for the supply of cutlasses, hoes, ploughs, harrows and tractors used in farm operations, while the industries in turn depend on agriculture as a market for their products and for raw materials such as metals and rubber; a strong farming demand keeps such factories in business.
• (ii) Processing industries: Agriculture supplies the raw materials (cocoa, oil palm, cotton, cassava, grains) that processing industries convert into finished goods, while the processing industries provide farmers with a ready market and add value to farm produce, thereby raising farmers' income.
• (iii) Agro-chemical industries: These supply farmers with fertilizers, herbicides, insecticides and drugs that raise crop yield and protect livestock, while agriculture provides the demand that sustains the chemical industries and, in some cases, the plant raw materials they use.

(c)(i) Farm surveying [2 marks]

Farm surveying is the measurement of a piece of farmland to determine its size (area), shape, boundaries and the relative positions of features on it, and to represent them on a plan or map.

(c)(ii) The 3, 4, 5 method [6 marks]

The 3, 4, 5 method is used to set out or check a right angle (90°) at a corner of a farm. It is based on Pythagoras' theorem: a triangle whose sides are in the ratio 3 : 4 : 5 must contain a right angle between the sides 3 and 4, because

\[3^2 + 4^2 = 9 + 16 = 25 = 5^2.\]

To use it: from the corner peg (O), a distance of 3 units (e.g. 3 m) is measured along one line and a peg fixed (A); from the same corner, 4 units are measured along the second line and a peg fixed (B); the distance between A and B (the hypotenuse) is then adjusted until it is exactly 5 units. When AB = 5, the angle at O is a perfect right angle. See diagram.

Maelezo ya Majibu

(a)(i) Natural pasture [2 marks]

Natural pasture is grassland made up of grasses, legumes and other herbs that grow on their own (naturally) without being deliberately planted or managed by man, and on which animals graze.

(a)(ii) Four characteristics of natural pastures in West Africa [4 marks]

• They are made up mainly of grasses with few legumes.
• They are dominated by tall, coarse grasses of low nutritive (feeding) value.
• They grow luxuriantly in the rainy season but dry up and become poor in the dry season.
• They contain a mixture of many different (unimproved) species and are often subject to bush burning.

(b) Root-knot disease of tomato [6 marks]

• (i) Causal organism: a nematode (eelworm), Meloidogyne species.
• (ii) Mode of transmission: spread through infested soil, and through movement of infected seedlings, farm tools, irrigation/run-off water and soil carried on implements or feet.
• (iii) Two symptoms: formation of knots, galls or swellings on the roots; stunted growth with yellowing and wilting of the plant (poor yield).
• (iv) Two control measures: practise crop rotation and use resistant varieties; treat/sterilise the soil with nematicides and destroy (uproot and burn) infected plants.

(c) Grafting versus budding [2 marks]

In grafting, a portion of stem (scion) bearing several buds is joined onto the rootstock, whereas in budding only a single bud is inserted into the bark of the rootstock.

(d) Two uses of sugarcane [2 marks]

• It is used for the production of sugar and syrup.
• It is chewed as food and used in making alcohol/ethanol and animal feed (by-products such as molasses).

Maelezo ya Majibu

(a) Four characteristics of a fertile soil [4 marks]

• It is rich in plant nutrients (nitrogen, phosphorus, potassium, etc.).
• It has good structure and texture that allow proper aeration and root penetration.
• It has a good water-holding capacity while still draining well.
• It has a favourable (near-neutral) pH and a good population of soil living organisms plus adequate organic matter (humus).

(b) Three factors that affect land availability for agricultural production in West Africa [6 marks]

• Land tenure system: Communal and fragmented ownership makes it difficult for a farmer to acquire and hold large continuous pieces of land for farming.
• Population pressure and urbanisation: Growing population and the expansion of towns, roads and industries take away farmland for building and other non-farm uses, reducing the land available for agriculture.
• Nature/topography and soil condition: Rocky, mountainous, waterlogged, eroded or desert (arid) land is unsuitable for cultivation, so such areas reduce the amount of usable farmland.

(c) Four benefits of draining farm lands [4 marks]

• It removes excess water and prevents waterlogging of the soil.
• It improves soil aeration, which favours root respiration and the activity of soil organisms.
• It raises soil temperature and allows the land to be worked and planted early.
• It reduces the incidence of water-borne pests, diseases and root rot, and reduces leaching of nutrients.

(d) Two sources of soil nitrogen [2 marks]

• Fixation of atmospheric nitrogen by leguminous plants (Rhizobium bacteria) and lightning.
• Decay of organic matter (plant residues, animal dung) and application of nitrogenous fertilizers.

Maelezo ya Majibu

(a)(i) Malnutrition in animal production [2 marks]

Malnutrition is a condition in which an animal is poorly nourished because its diet is unbalanced, that is, it lacks or has too little (or an excess) of one or more essential nutrients such as proteins, minerals, vitamins or energy.

(a)(ii) Four effects of malnutrition on farm animals [4 marks]

• Stunted (retarded) growth and loss of body weight.
• Low productivity, that is, poor milk, egg or meat yield.
• Reduced fertility and poor reproductive performance.
• Lowered resistance to diseases, leading to easy infection and sometimes death.

(b) Methods of rangeland improvement [6 marks]

• (i) Rotational grazing: The range is divided into paddocks and the animals are moved from one paddock to another in turn, so that grazed portions are rested and allowed to regrow; this prevents overgrazing and gives even utilisation of the pasture.
• (ii) Reseeding: Improved and more nutritious grass and legume seeds are sown to replace poor or worn-out species, thereby raising the quality and quantity of forage on the range.
• (iii) Controlled stocking: The number of animals kept on the land is matched to its carrying capacity so that the pasture is neither overgrazed nor undergrazed, keeping the range productive.

(c) Four objectives of animal improvement programmes in West Africa [4 marks]

• To develop breeds that grow faster and give higher meat, milk or egg yield.
• To breed animals that are resistant to diseases and parasites.
• To produce animals well adapted to the tropical (hot) climate and local feeds.
• To improve fertility/prolificacy and the overall quality of the national herd.

Maelezo ya Majibu

(a) Law of diminishing returns

The law of diminishing returns states that when successive units of a variable factor are added to fixed factors of production, total output will initially increase, but after a certain point each additional unit of the variable factor adds less to total output than the preceding unit.

(b)(i) Input-output graph

Using the scale shown by the axes, plot the following points and join them with a smooth curve:

Fertilizer input (bags)	Sorghum yield (kg)
0	8
6	30
12	50
18	90
24	140
28	170
32	190
36	200
40	200
46	190

(b)(ii) Relationship between fertilizer input and sorghum yield

1. As fertilizer application increases from 0 to 36 bags, sorghum yield increases from 8 kg to 200 kg.
2. After about 24 bags, additional fertilizer gives progressively smaller increases in yield: 30 kg from 24 to 28 bags, 20 kg from 28 to 32 bags, and 10 kg from 32 to 36 bags. This is the stage of diminishing returns.
3. At 36 to 40 bags, the maximum yield of 200 kg is reached. Further application to 46 bags reduces yield to 190 kg, showing negative returns.

(c) Functions of an agricultural extension agent

1. Teaches and demonstrates improved farming methods and innovations to farmers.
2. Serves as a link between farmers, government and agricultural research institutions.
3. Disseminates agricultural information and advises farmers on farm management problems.
4. Assists farmers to obtain farm inputs, credit facilities and marketing information.

(d) Benefits of commodity boards in the marketing of agricultural produce in West Africa

1. They provide a ready market for agricultural commodities.
2. They announce guaranteed prices and help to stabilize farmers' incomes.
3. They carry out grading, standardization and quality control of produce.
4. They provide storage, processing, transportation and other marketing services.
5. They assist farmers with credit, subsidies, farm inputs and technical advice.