Power. Amount of work done per unit of time.

  1. Human power.

It is limited to very light tasks and quality of work produced is low.

They give0.07kw to 0.1kw for healthy human being.

ii.       Animal power.

Power from animals such as donkeys, oxen and camels.

Advantages of animal power.

  1. It does not require skilled workers as compared to engine power.
  2. Animals are cheaper to buy and maintain compared to tractor engine power. iii. Work out from animals is higher than from human beings.
  3. Animals can work in areas where it would be impossible for tractors such as in hilly terrain.
  4. Animals work better on small holdings than tractors.

Disadvantages of using animal power.

  1. Animals need a pig portion of land for grazing as part of their maintenance. ii. They are slower than tractors and cannot cope with very large amount of land. iii.   Animals can damage crops when they are used for weeding. iv.   Animals sometimes get sick hence reducing their work output.

 A yoke.

Piece of wood which is made in such a way that it can rest on the animal’s neck.

Wind power.

Provides power to do light jobs in the farm such as winnowing of crops.

It may be used to pump water.

However wind is rarely used because of its unreliability in direction, strength and availability.

Water power.

It is limited because:

  • Most rivers are small and seasonal.
  • It is expensive to harness the power.
  • Most farms do not have access to large quantities of moving water.

Used to drive maize grinding mills, drive hydraulic pumps, for pumping water.

  • Biomass

Include biogas and wood/charcoal.

Wood and charcoal.

Modern jikos have being designed to reduce energy loss from burning charcoal. Alternatives have also being sought in the use of sawdust and coffee husks.


Gas produced when organic wastes e.g. animal dung is fermented in a digester producing methane.

Stage 1.

Insoluble organic substances are broken down by microbes in digestive system of the animal coming out in form of waste.

Stage 2. 

Soluble substances in the dung are broken down by the microbes in the digester.

Uses of biogas.

  1. Cooking and lighting. ii. Internal combustion engine.


Advantages of biogas.

  1. It is economical for farmers with enough zero grazing animals and resources to construct a biogas plant. ii. The liquid by-product of fermentation process (effluent) is a better quality fertiliser (has more available nitrogen).

iii.      Potentially harmful wastes of cows and pigs are removed from the zero grazing enclosures.  That is, flies cannot breed and unpleasant odours are removed.


  • The initial capital is high. Construction of a biogas digester is expensive.
  • Requires high management to produce the gas.
  • Requires large number of farm animals to sustain the production of the gas.

Solar radiation.

Radiant energy from the sun.

Needed for drying of most crops prior to storage and processing.

General uses of solar energy.

  1. For drying some farm produce and other materials.
  2. For heating water. iii. For distillation of clean drinking water. iv. For cooking.
  3. For generating electricity.

Electrical power.

May be obtained from geothermal power station, hydropower station, nuclear station or a storage battery.


Energy contained in moving water as it descends a lower level or towards a sea level. The power of moving water is harnessed to produce electricity in the farm.

Storage battery.

It stores electrical energy which is supplied when required to operate farm machinery and for general lighting.

Fossil fuel.

These include fossil fuel such as petroleum oils, coal and natural gases.


Extracted from oil wells. It is then refined to get by-products such as petrol, disesel, kerosene, jet oil, lubricants and petroleum gas.


Fossil fuel made up of vegetable matter laid down in swampy areas and buried under other materials. Consist mainly of amorphous deposits. Coal is bulky.

Peat. A young coal consisting of partially decomposed organic matter and inorganic minerals that have accumulated in water saturated environment.

Natural gases.

Consists of liquid hydrocarbons from animal and vegetative matter laid in sedimentary rocks.



Tractor engine.

The modern tractor has an internal combustion engine which burns petrol or diesel to produce power.

Tractor is a mechanical device which converts fuel to mechanical energy.

The tractor engine is a four stroke cycle engine that uses diesel or petrol as fuel.

Four stroke cycle engine.

The cycle is completed in four strokes during which the crankshaft makes two total revolutions. The cycles are;

  • Induction stroke.
  • Compression stroke.
  • Power stroke.
  • Exhaust stroke.

Induction stroke.

The piston is moved down the cylinder causing the inlet valve to open drawing in fresh supply of petrol vapour and air into the cylinder.

Compression stroke.

In this phase, the valves are closed and the piston moves up the cylinder. This compresses the fresh fuel mixture in the combustion chamber.

The power stroke.

Both valves are closed. The fresh fuel mixture is fully compressed and a spark is produced by

the spark plug. This causes the fuel mixture to ignite and expand resulting in pressure that force the piston down the cylinder.

The exhaust stroke.

This is the last phase where the piston move up the cylinder to eliminate the burned fuel mixture through an open exhaust valve.

Advantages of four stroke engines.

  1. The engines produce high power and can do heavy farm work.
  2. They have efficient fuel and oil utilisation. iii. They perform a wide range of farm operations.
  3. The engines are efficiently cooled with water thus allowing the production of large engine size.
  4. The exhaust gases are effectively expelled from the cylinders.


  1. They are expensive to buy and maintain.
  2. Their use is limited in areas. iii. They require skilled personnel and support services.

 The two stroke cycle engine.

Commonly found in small machines like; mowers, chain saws, motor bikes and water pumps that do light jobs.

It has no valves, instead it has three ports namely; inlet, transfer and exhaust.

The ports are located on the cylinder wall and are opened and closed by movement of the piston.


Induction and compression stroke.

At the start of the cycle, the piston is at the bottom. As the piston moves upward, it uncovers the inlet port and the mixture is drawn in., when the piston reaches the top, ignition occurs and the piston is forced downwards compressing the mixture in the crankcase.

Power and Exhaust stroke.

The ignited gases cause a build-up of pressure in the combustion chamber which forces the piston downwards. This covers the inlet port and traps fresh fuel mixture in the crankcase. As the piston moves further down, it uncovers the exhaust port and the transfer of the fuel mixture from the crankcase to the combustion chamber.

Advantages of two stroke cycle engines.

  1. They are not expensive to buy and maintain. ii. They are economical in fuel consumption. iii.       They can be used in a wider range of farm land including hilly areas.
  2. They can do small tasks within the farm which would be uneconomical to do using four stroke engine.


  1. They produce less power hence cannot be used for heavy duties.
  2. They are inefficient in burning fuel to produce power. iii. They are air cooled thus limiting the size of the engine.

Systems of a tractor.

Fuel system.

Categorised into two depending on the fuel used.

The petrol fuel system.

Petrol is put in a tank and passed to the carburettor through a pipe which is fitted with a filter or an on-off tap.

The carburettor is a device that turns liquid petrol into vapour and mixes it with definite amount of air. When air is passes over the end of a narrow tube or a jet that contains the fuel, some of the fuel is drawn out and passed into the air stream.

 Maintenance of petrol fuel system.

  • The carburettor jets should be cleaned regularly to avoid blockage.
  • The fuel filter should be cleaned by washing in petrol.
  • The hole in the fuel tank cap should always be kept clean.


Diesel fuel system.

Does not have a carburettor and the fuel is pumped and distributed in the system by steel pipes. The pump meters inject the exact volume of diesel needed in each cylinder. Deliver pipes are fitted with series of fuel filters where dirt is trapped and the fuel enters the injector pump when it is clean. In the injector pump, it is subjected to very high pressure and it is delivered to the cylinders in spray like drift. A permanent bleed line is fitted to connect the bleed points to the fuel tank. This helps to return excess fuel back to the fuel tank.

Maintenance of a diesel fuel system.

Filters should be replaced as recommended by the manufacturers.

Bleeding should be done in case air is trapped in the system.

The sediment bowl should be cleaned regularly.

Structural and functional differences between petrol and diesel engines.

Petrol engine. Diesel engine.
It has a carburettor. It has an injection pump.
Fuel and air are mixed in the carburettor before it gets into the engine. The fuel and air are mixed within the cylinder.
Fuel is ignited by an electric spark. Fuel is ignited by compression of air and fuel mixture in the cylinder.
It produces little smoke because petrol is completely burnt. It produces a lot of smoke since the diesel is not completely burnt.
Petrol engine is light in weight and suited for light duties. It is relatively heavy in weight and suited to heavy duties.

Electrical system.

Consist of the ignition circuit generator (dynamo) circuit, starter motor circuit and lighting circuit. The battery stores electrical energy supplied by the charging system.  The electrical energy produced by the running engine which is driven by a generator charges the battery.

Care and maintenance of a tractor battery.

  1. The level of electrolyte should be kept just above the plate by topping with distilled water.
  2. Corroded terminals should be scrapped clean and smeared with grease. iii. The battery should be tightly fixed in a box to avoid spillage and damage.
  3. The battery should be fitted correctly on the tractor.
  4. The battery should be charged regularly and periodically.
  5. In case of long storage the battery the contents should be emptied and the battery kept upside down. vii. The generator fan belt should always be functional to ensure the battery is always charged.

The ignition system.

The ignition system of petrol engine consists of ignition coil, the distributor, contact breaker and the condenser. In spark ignition system, the battery or generator supplies the sparks required for ignition.

The ignition coil.

Converts the battery voltage from 12 volts to about 600 volts. Provides a spark at the sparking plugs located in the engine cylinders.

The distributor. 

Causes the spark to occur at each cylinder in the required firing sequence.

Contact breaker. 

It interrupt the normal flow of current in the primary circuits. This results in the generation of high voltage from the coil that produces the required spark.


Absorbs the self  induced current in the primary circuit thus preventing the contact breaker points from excessive heating.


Common faults of ignition system.

Sudden stopping.

Caused by:

  • Poor terminal connection.
  • Faulty ignition system.


  • Proper tightening of the terminals.
  • Proper cleaning and readjustment of the terminals.

Continuous engine running.


  • Broken leads.
  • Poor terminal connection.
  • Faulty contact breaker.


  • The broken leads should be replaced.
  • The leads should be cleaned and tightened regularly.

Maintenance of ignition system.

  1. The carbon deposits on the spark plug electrodes should be removed.
  2. The spark plugs whose electrodes are worn out should be replaced.
  3. The contact breaker points should be cleaned.
  4. The breaker points should be adjusted so that they lie between 0.3mm and 0.5mm.
  5. The condenser should be replaced regularly.

 Cooling system.

Power production gives a lot of heat. This heat should be reduced. Too much heat within the engine may lead to overheating and hence expansion of engine components. Expansion of engine components distorts its shape causing gas leakage, valve burning, and loss of engine power and even cracking of the cylinder or its end.

Cooling system aims at preventing the engine from overheating which would cause piston seizure in the cylinder.


Types of cooling systems.

Air cooled system.

Commonly used in light weight farm machine such as mowers, motor-bikes and landmasters.

Characteristics of air cooled engines.

  • They are simple in construction.
  • They have a fan blade which assist the circulation.
  • They are light in weight as they have no radiators and water jackets.

Problems of air cooled Engines.

  • They get hot quickly and use heavy lubricating oils.
  • The cooling is not adequate under all conditions especially when carrying heavy loads.

Water cooled system.

Water is used to absorb heat from the engine block. The major components of water cooled engine are the radiator, water jackets, water hoses, water pump, thermostat and a fanning mechanism. Cooled water is sucked from the bottom part of the radiator with the help of a water pump. It is pushed through the water jackets and circulates within the engine block and the cylinder head. Thermostat is used to regulate the temperature of water in the engine at 8090 degree. When water is too hot it is forced back to the radiator for further cooling.

Care and maintenance of water cooling system. 

  1. The water pump should be lubricated regularly.
  2. Clean water should be used in the radiator and trash removed from the fins.
  3. All pipes should be fitted tightly to avoid leakage.
  4. The radiator should be filled with clean water before starting day’s work.
  5. Fan belt tension should be checked regularly and if too tight or too loose should be adjusted accordingly.

Lubrication system.

Aimed at supplying oil to all parts of the engine where friction is likely to occur.

Importance of lubrication system.

  1. Helps to increase efficiency of the machine and reduces the rate of wear and tear of moving parts.
  2. Reduces the heat created by the rubbing surfaces and acts as a seal between them.
  3. Acts as a cleaning agent because it washes off all the dust, dirt, soot and meat chippings from the oil paths to the sump.
  4. Oiling prevent rusting of stationery machines.

 Types of lubrication systems.

  1. Splash feed type,

The cranks of the crank shafts are dipped in the oil and splashed up as they move. Not a good type of lubrication.

  1. Force feed type.

The oil in this case circulates around the engine and drips back to the oil sump. A dip stick is used as an indicator of how much oil is in the oil sump. The components of this system are:oil sump, pump, filters and oil ways around the cylinder block, pistons, connecting rod, camshaft, crankshaft and the valves.

  1. Oil mist type.

Common with two stroke cycle engines. The oil is mixed with fuel mainly petrol in the tank at the rate of 0.25L of oil to 6L of petrol.


Types of lubricants. 

The type of lubricant is identified with its thickness (viscosity index) which is indicated by S.A.E scale (Society for Automobile Engineers). The lower the SAE number, the thinner the oil.

  1. SAE 10. Thin engine oil that gives little protection when heated.
  2. SAE 50. Thicker engine oil recommended for protecting the bearings.
  3. SAE 90-150. Transmission oils recommended for clutch, gear box, wheel lubrication and ball bearings.

Care and maintenance of lubrication system.

  1. Old or contaminated oil should not be used for lubrication.
  2. Oil; should be drained when still hot to avoid sticking on the walls of the sump.
  3. The oil filters should be replaced when necessary.
  4. The correct type of oil should be used as per the manufacturer’s instructions.

The power transmission system.

The function if this system is to transfer power from the engine to the drive shaft, the axle wheel, the power take off shaft and the hydraulic system.

The clutch.


  •  Connect or disconnect the drive shaft to and from the engine respectively.
  • Enables the driver to take off gradually and smoothly.The clutch uses friction force to transmit power from the engine. The friction depends on resistance motion and the roughness. Has three basic parts: crank shaft, friction disc and the pressure plates

Pressure plate.

Provides force on the friction disc when the clutch is engaged. Made up of either brass, copper or asbestos which are good conductors and hard to break.


Has external splines which are meshed with internal splines of the friction disc.

The gear box.

Provides different forward speeds. Allows the driver to select any forward or reverse gear to suit the operation.

Can also allow change in the speed. Allows the driver to stop the tractor without suddenly stopping the engine or without keeping his foot pressed on the clutch.


The differential. 

It allows change in direction of the drive to right angles so that power is transmitted to the rear wheels. Enables the rear wheels to travel faster or slower than the other especially when negotiating a corner. Thus enables the tractor to turn without skidding. Wheel skidding would make it difficult to control the tractor and increase rate of wear of the tyres.

The presence of differential lock avoids the wheel slip or skidding.

Composed of the drive pinion, the ring pinion gear, differential side gears and the axial drive to the wheel.

This is where the wheels propel the tractor machine either forward or backward enabling the tractor to move and do useful work. The tyres allow maximum grip/traction. The wheel provide large surface area of contact between the tyres and the ground.

Power transmission mechanism.

Power from the engine is made available through the following.

  • The propeller shaft.
  • The power take off shaft.
  • The hydraulic system.
  • The draw bar.
  1. The propeller shaft.

Connect the gearbox to the differential that has axles which drive the wheels making the tractor to move.

  1. The power take off shaft. (PTO)

Located at the rear part of the tractor and rotates at same speed as the crankshaft. Can be connected to machines such as mowers, planters, Rotavators, sprayers and fertiliser spreaders.

  • The hydraulic system.

It is operated by use of a lever near the driver’s seat. Attached to the three point linkage which lowers or raises the mounted implements such as ploughs, mowers, planters and sprayers.

iv.      Draw bar.

Located at the rear part of the tractor. Serves for the attachment of trailed implements used during harrowing, transportation or rolling.


Short term service.

  1. The engine oil should be checked daily by use of a dip stick. If the oil level is low it should be added. ii. The fuel level should be checked at the start of every day’s work and added if necessary.
  2. Water level in the radiator should be inspected and if necessary topped up.
  3. The level of the electrolyte should be checked daily and if it drops below the recommended level, it should be topped up withy use of distilled water.
  4. The nuts and bolts should be tightened every day if loose. Lost nuts and bolts should be replaced before the day’s work.
  5. Grease should be applied by use of grease gun through the nipples. vii. Large sediments from the sediment bowl should be removed.
  6. The tyre pressure should be checked every morning before the day’s work by use of pressure gauge. It should be inflated or deflated as required in the machines manual.
  7. The fan belt tension should be checked to ensure that it deflects between 1.9cm-2.5cm when pushed.
  8. The brake shaft bearing should be greased. Ensure that the brake fluid level is maintained at the recommended level.


Long term service.

  1. The engine oil should be drained completely from the sump and replaced with new oil.
  2. The steering gear box oil should be inspected and refilled if it goes below the recommended level.
  3. The oil in the differential should be replaced as recommended.
  4. The linkage and the pulley attachment should be replaced. The pulley oil level should also be checked and added if necessary.
  5. The dirty oil should be removed and replaced with clean one.

Farm implements.

Tractor drawn implements.

Categorised depending on the attachment method.

Attachment methods.

  1. One-point hitch implements.

Attached to the tractor at only one point that is the drawbar.  Include: trailed implements such as trailers, heavy harrows, planters and rollers.

  1. The three-point hitch implements.

Attached to the tractor at three points that is the top linkage point and two lower link attachment points. Are operated by the hydraulic system of the tractor.  Include: ploughs, most harrows, sub-soilers, planters, mowers, ridgers, sprayers, Rotavators etc.


Used mainly for transporting goods. Attached to the rear by means of the drawbar. They have double rear wheels. Some are fitted with a hydraulic mechanism for off-loading.


  1. All the moving parts of the trailer should be lubricated.
  2. The tyre pressure should be checked regularly. If the pressure is low or high, it should be adjusted to the correct pressure.Worn-out tyres should be replaced.
  3. Nuts and bolts should be checked. If loose they should be tightened and those wornout should be replaced.
  4. The implement should be kept under a shed if not in use.



Implements for primary cultivation. There are two types of ploughs.

  • Disc ploughs.
  • Mouldboard ploughs.

 Disc plough.

Has heavy concave discs of about 60-70cm in diameter. Each disc is mounted on a standard an all standards are fixed to the beam. Most ploughs have three discs. The discs may be plain or notched. Notched discs are more effective in cutting into hard soil. The disc plough does not turn the furrow slice completely. The rolling action of the disc enable the plough to ride over obstacles.

It also works well in wet, sticky, non-scourin

Parts of a disc plough.

  1. The beam.

Long heavy bar that provides attachment for all parts of the plough.

ii.       Disc.

Concave in shape. They cut, turn and invert the furrow slices.

iii.    Scrapers.

Each disc has a scarper to remove wet from the disc. They also aid in turning and inverting the furrow slice.

iv.     Standards.

Also known as hangers. Connect the disc to the plough beam. Have hubs fitted to them which facilitate the movement of the discs.

  1. Furrow wheel.

Fitted at the rear of the plough. Rides over the dead furrow counteracting the thrust created by the discs thereby balancing the whole equipment. Also used to adjust the depth of ploughing.

Maintenance of a Disc plough.

  1. The hubs and furrow wheel bearings should be lubricated as recommended.
  2. The plough should be cleaned after a day’s work. iii. Broken discs should be repaired immediately.
  3. All unpainted surfaces of the plough should be smeared with old engine oil during long storage.
  4. Loose nuts and bolts should be tightened.
  5. Blunt discs should be hammered.

Mouldboard plough.

Plough suited to fields that do not have many obstacles such as roots, stones and stumps.

During operation the plough cuts and turns over the furrow slice completely thus covering surface vegetation. It operates at a uniform depth once adjusted.


Components of the mouldboard plough.


Made of cast iron thus can break easily. Makes horizontal cutting on the furrow slice, and thereafter starts turning it over. Wears off easily.


Continues with the action of turning the furrow slice that had been initiated by the share. Completes the turning of the furrow slice.

The disc coulter.

Rotating disc with a sharp edge. Located above the share. Cut the furrow slice separating it from the unploughed land. Also cuts trash.


Presses against the wall of the land being ploughed hence helps to counteract side pressure excreted by furrow slices on the mouldboard and share thus stabilising the plough.

 Depth wheel.

Fixed at the back of the plough. Used to control the depth of ploughing.

Maintenance of mouldboard ploughs.

  1. The moving parts of the plough should be lubricated.
  2. Shares should be kept tight and sharp. iii. All nuts and bolts should be checked regularly and if loose they should be tightened.
  3. All trash and wet soil should be scarped clean or washed from the surface of the implement at the end of the day.
  4. All unpainted surfaces should be coated with old engine oil in order to preventing rusting during storage for long periods.
  5. Worn-out parts should be replaced.

Operational differences between a disc and a mouldboard plough.

Disc plough.


Mouldboard plough.
Can be used on a field with obstacles such as stones, roots and stumps because of the rolling action of the disc. It is rigid and slides along in operation therefore it cannot be used on fields which have hard soils, stones or stumps because it cannot ride over them.
Does not invert the furrow slice completely. Therefore it leaves a rough field. Inverts the furrow slices completely leaving a clean filed.
More secondary operations are necessary after a disc plough has been used. Fewer secondary cultivation are needed.
Cuts at varying depths because whenever it comes across obstacles it rides over them. Operates on uniform depth because once the share is in the soil it follows the same depth.
It is not easily broken by obstacles because it rides over them. It is rigid and therefore can easily be broken by obstacles it comes across.
Requires less power to pull when operating. Requires more tractor power to pull when operating.



Used for secondary tillage. Their main uses are to level the seedbed, break soil clods, stir the soil and destroy weeds. They may also be capable of burying trash.

Types of harrows.

Disc harrows.

Has concave discs which are in series f 5-8 discs. Are joined together on a shaft to form gangs and are set at a certain angle to the direction of travel. Discs can be plain or notched. Notched discs tend to cut the furrow slice and the soil better. Gangs on discs are arranged in patterns called tandems. Tandem arrangement makes operations more effective.

Maintenance of Disc plough.

  1. The disc bearings should be lubricated after a day’s work.
  2. The discs that are damaged should be repaired or replaced.
  3. Trash or soil should be removed from the harrow after use.
  4. Old engine oil should be applied on all parts of the harrow before storage for long periods.
  5. Bolts and nuts that are loose should be tightened.

Spring tine harrows.

Has coiled steel tines which are mounted on a frame of beams. They break the soil colds by means of a vibrating effect of the tines. It also collects trash and level the ground.

Maintenance of spring tine harrows.

  1. The worn out tines should be replaced.
  2. Bolts and nuts should be checked and those that are loose tightened and the lost ones replaced.
  3. Should be cleaned at the end of the day’s work.
  4. Unpainted parts should be oiled if the implement is to be stored for a long time.

Spike tooth harrow.

Has several strong pointed spikes or tines which are mounted on a frame of beams. Spikes are either curved or pointed at the tips. Used for incorporating fertilisers into the soil, breaking the soil clods, levelling the surface and to remove trash from the field.

Maintenance of spike tooth harrow.

  1. Worn out parts should be replaced.
  2. Should be cleaned at the end of the day’s work.
  3. Loose nuts and bolts should be tightened.
  4. Unpainted parts should be oiled before long storage.


Heavy implements used for breaking hard pans and facilitating aeration and water infiltration.

Maintenance of sub-soilers.

  1. Worn out parts should be replaced or repaired.
  2. Unpainted parts should be oiled during long storage to prevent rusting.
  3. Should be cleaned after the day’s work.
  4. Should be stored in a shed when not in use.



Implements used to make ridges. Made of two mouldboards fixed on the standard back to back.

Maintenance of ridgers. 

  1. The soil sticking onto the mouldboards should be scrapped off after a day’s work.
  2. The worn out shares should be replaced and broken parts repaired.
  3. Should be stored in a shed when not in use.
  4. Loose nuts and bolts should be tightened.
  5. Unpainted parts should be oiled to prevent rusting for long storage.


Implements used in soft soil conditions. Useful in rice paddy fields where they produce a fine mud in preparation for planting. Operated by P.T.O.

Maintenance of Rotavators.

  1. Should be cleaned after day’s work.
  2. Worn out parts should be replaced.
  3. Moving parts should be lubricated.
  4. Loose nuts and bolts should be tightened.


Machines used for cutting grass for hay making and cutting silage crops where forage harvesters are not available. Used to clear vegetation before ploughing.

Many are driven by P.T.O shaft and mounted onto the tractor.

Types of mowers.

  • Reciprocating mower.
  •  Rotary mower.

 Reciprocating mower.

Has fingers fixed on a cutter bar held horizontally during the operation. Has a set of cutting blades fixed on a long metal bar to form the cutting knife.

Maintenance of reciprocating mowers.

  1. Blades of the cutting knife should be kept sharp.
  2. Worn out blades should be removed and then replaced.
  3. Loose bolts and nuts should be tightened.
  4. Moving parts should be lubricated with grease before the start of the day’s work.

Rotary mower (Gyro-mower).

Driven by P.T.O. some are trailed while others are mounted on the three hitch point. Cutting of the vegetation is done by blades fitted on a horizontal disc. Blades are rotated at a high speed by the rotating disc. The blades and the disc are enclosed in a metal cover on the upper side. This prevents flying objects thrown by the blades from causing damage. Works better on uneven ground.

Maintenance of rotary mower.

  1. The blades must be checked for sharpens. If blunt they should be sharpened.
  2. Worn out blades should be replaced.
  3. The mower should be cleaned after a day’s work.
  4. Loose nuts and bolts should be tightened.
  5. Worn out guard should be repaired or replaced to ensure total protection.
  6. Rotating parts should be lubricated. vii. Unpainted parts should be cleaned and oiled before long storage.



Machines used for placing seeds at the correct spacing, depth and density. Have a mechanism for opening seed drills which enable the seeds to be planted in rows. The depth of planting can be controlled by adjusting the coulter. There is a mechanism for covering lightly by the trailing wheels.

Maintenance of planters and seeders.

  1. Moving parts should be lubricated.
  2. Seed hoppers and fertiliser containers should be cleaned after use.
  3. Loose nuts and bolts should be tightened.
  4. Broken parts and worn out parts should be repaired or replaced.
  5. The coulter tubes should be free of any blockage for efficient seed passage.


Implements used for shallow cultivation in light soils. The beam is fitted with adjustable tines which make it suitable for weeding crops of different spacing.

Maintenance of cultivators. 

  1. Loose nuts and bolts should be tightened.
  2. Trash and soil should be removed from the implement after use.
  3. Broken and worn out tines should be replaced or repaired.
  4. Should be kept in the shed during long storage.


Used for applying either pesticides, herbicides or foliar feeds. Consist of a pump that lifts the chemical from the tank to a boom containing a number of spray nozzles. Have a mechanical agitator that continuously mixes the liquid for uniformity.

Maintenance of sprayers. 

  1. The tank of the sprayer should be drained before and after use.
  2.  All the nozzles should be removed and cleaned when blocked.
  3. The tank and all other parts should be washed thoroughly with clean water and dried.
  4. All parts that are prone to rusting should be cleaned and painted.



  1. Combine harvester for harvesting grain crops.

They are not tractor drawn or mounted implement but are self-propelled machines which do all the harvesting operations including threshing and cleaning the grains. Harvest different cereal crops with appropriate adjustments.

  1. Root-crop harvesters.

Harvest crops like potatoes and groundnuts. Most common root harvesters are the ridgers.

iii. Forage harvesters.

Implement use to harvest forage crops such as maize, sorghum and nappier grass. Mounted on the tractor and operated by P.T.O shaft. The harvest and chop the forage materials to appropriate size. Other implements that may be used are hay balers and mowers.

Maintenance of forage harvester. 

  1. Moving parts should be lubricated.
  2. Cutting edges should be sharpened.
  3. Bolts and nuts should be tightened if loose.
  4. Trash and dirt should be removed after use.
  5. Should be kept under a shed when not in use.
  6. For long storage it should be oiled to prevent rusting.




Stationary implements which are either hand or tractor-driven depending on the size. Consist of rotating serrated disc, which scrapes off maize from the cob as they are fed into the machine.



Used for ploughing, weeding, opening furrows for planting and harvesting crops such as groundnuts.

Parts of ox-plough.

  1. Beam

Component onto which all other parts of the plough are attached. Also adds weight to the plough for better penetration.

  1. Handles

There are two handles. Enables the operator to set the implement in the proper direction when ploughing.

  • The mouldboard.

Inverts furrow slices.

iv.      Share.

Cut the furrow slice horizontally.

  1. Landside.

Presses against the wall of the unploughed land thus helps to stabilise the plough.

vi.         Land wheel.

Regulate the depth of ploughing.

vii.       Draft rod.

Metal bar attached to the main beam of the plough. At the front end of the draft rod there is a chain that connects it to the yoke. The rod and the chain forms the draught mechanism of the plough.

Maintenance and repairs of an ox-plough.

  1. The land wheel bearing should be lubricated.
  2. Worn-out shares should be replaced. iii. Blunt shares should be sharpened by hammering.
  3. Before the day’s work check for loose nuts and bolts and tighten them if they are loose.
  4. If the ox-plough is to kept for long periods, its surfaces should be coated with old engine oil.
  5. Should be kept in a shed when not in use.

Ox-tine harrow.

Used for breaking soil clods. Collecting trash, levelling the seed-bed and covering planted seeds.

Maintenance of ox-tine harrow.

  1. Any broken or worn out tine should be repaired or replaced.
  2. Should be cleaned after use.
  3. Should be stored in a shed.
  4. For long storage, oil should be applied to prevent rusting.


These are harnessed to the animals by means of a yoke.



  1. The moving parts should be oiled or greased regularly in order to reduce friction wearing.
  2. The yoke should be properly maintained.
  3. Tyre pressure should be checked daily before the start of the work and adjusted accordingly.
  4. Other visible damages on the cart should be repaired. 

Advantages of animal drawn implements compared to tractor drawn implements.

  1. The initial cost of purchasing the animals, the yoke and the implements is much lower than that of buying the tractor and the implements drawn by the tractor.
  2. A person who operates animal drawn implements requires less training than one who operates the tractor.
  3. Tractor need regular maintenance and minor repairs which most farmers do not have the skill to carry out. These are also expensive.
  4. Animal drawn implements can be used in areas where land is steep which are not suitable for tractor drawn implements.

Disadvantages of animal drawn implements as compared to tractor drawn implements.

  1. They are more tedious than tractor drawn implements. The operator has to keep on guiding the implement and the animal.
  2. More than one person is required to guide the plough and the animal while cultivating whereas one person is required to plough using a tractor. iii. Animal drawn implements are slower than tractor drawn implements.
  3. Animals get tired at times and this slows down the work.
  4. There are diseases in some areas which makes it difficult to use some animals.
  5. A farmer need to set aside a piece of land where he can either grow a fodder crop or develop a pasture for the animals.




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