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PEC EPE Agricultural practice questions

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Question 1Agricultural Engineering

In a Massey Ferguson MF 4700 tractor's hydraulic three-point hitch, which component controls the working depth of a mounted plough by sensing draft force?

  1. The stabiliser sensing the draft load
  2. The lower link sensing the draft load
  3. The drawbar sensing the draft load
  4. The top link sensing the draft load Correct answer.

Explanation

The MF 4700 senses draft through the top link. Changes in the force transmitted through this link provide the draft-control signal. When draft rises above the set value, the linkage lifts the implement to reduce its working depth and load. Other tractor designs may use lower-link sensing.

Question 2Agricultural Engineering

A centrifugal pump delivers 30 L/s against a total head of 20 m. Taking water density as 1000 kg/m³ and g as 9.81 m/s², what is the hydraulic power output?

  1. 5.9 kW Correct answer.
  2. 0.6 kW
  3. 2.0 kW
  4. 3.0 kW

Explanation

Hydraulic power equals density × g × discharge × head, i.e. 1000 × 9.81 × 0.030 × 20 ≈ 5886 W, about 5.9 kW. The discharge must be converted from litres per second to cubic metres per second before substitution.

Question 3Agricultural Engineering

Which soil moisture tension range is generally used to trigger irrigation for most field crops on a medium-textured soil?

  1. Around 1.5 to 2.0 MPa
  2. Around 3.0 to 4.0 MPa
  3. Around 0.03 to 0.05 MPa Correct answer.
  4. Around 0.5 to 1.0 MPa

Explanation

Field capacity corresponds to about 0.01 to 0.03 MPa and the permanent wilting point to about 1.5 MPa. Irrigation is normally scheduled before the allowable depletion is exceeded, typically when tension reaches roughly 0.03 to 0.05 MPa for sensitive crops. Higher tensions indicate severe stress.

Question 4Agricultural Engineering

A field has a net irrigation requirement of 40 mm and the application efficiency of the system is 80 percent. What gross irrigation depth must be applied?

  1. 32 mm
  2. 40 mm
  3. 50 mm Correct answer.
  4. 64 mm

Explanation

Gross depth equals net depth divided by application efficiency expressed as a decimal, so 40 ÷ 0.80 = 50 mm. Efficiency below 100 percent means more water must be delivered than the crop actually uses.

Question 5Agricultural Engineering

In a seed drill metering system, what is the main function of the fluted roller?

  1. To break soil clods ahead of the seed furrow
  2. To meter seed at a rate proportional to roller speed Correct answer.
  3. To press seed into the furrow after placement
  4. To separate chaff from seed in the hopper

Explanation

Fluted rollers rotate at a speed set by the drill calibration and ground drive, discharging seed from the hopper at a rate proportional to roller rotational speed. Adjusting the roller exposure or gear ratio changes the seed rate. Clod breaking and pressing are handled by separate soil-engaging components.

Question 6Agricultural Engineering

Which threshing principle best describes a conventional rasp-bar cylinder and concave in a combine harvester?

  1. Air blast separation in a vertical chamber
  2. Centrifugal separation in a rotating bowl
  3. Gravity settling on an inclined belt
  4. Impact and rubbing between cylinder bars and concave Correct answer.

Explanation

In a rasp-bar cylinder, grain is threshed mainly by impact from the bars and rubbing against the concave, with some shear. Clearance and cylinder speed control the severity of threshing. Air blast and gravity separation belong to cleaning and conveying stages, not threshing.

Question 7Agricultural Engineering

A disc plough is preferred over a mouldboard plough in a field with hard, dry, stony soil mainly because the disc plough:

  1. Requires a lower draught per unit width in all soils
  2. Inverts the furrow slice more completely
  3. Scours freely and rides over obstructions Correct answer.
  4. Leaves a smoother furrow bottom

Explanation

Rolling discs cut and turn soil by rotation, so they scour in sticky or dry conditions and ride over stones rather than being deflected or broken. Mouldboard ploughs give better inversion but are more easily damaged and fail to scour in hard dry soil.

Question 8Agricultural Engineering

In a sprinkler irrigation system, two sprinklers with the same nozzle size operate at different pressures. What happens to the discharge of the higher-pressure sprinkler?

  1. It increases linearly with pressure
  2. It decreases because pressure reduces droplet size
  3. It increases approximately with the square root of the pressure ratio Correct answer.
  4. It stays the same because nozzle size is unchanged

Explanation

Orifice discharge follows Q = C·A·√(2gH), so for a fixed nozzle area the flow varies with the square root of the pressure head. Doubling pressure therefore raises discharge by about 41 percent, not by 100 percent.

Question 9Agricultural Engineering

A farmer wants to reduce soil erosion on a sloping field used for row crops. Which combination is most effective?

  1. Burning crop residue and leaving the surface bare
  2. Contour cultivation with conservation tillage and grassed waterways Correct answer.
  3. Straight up-and-down slope cultivation with clean tillage
  4. Deep ploughing along the slope each season

Explanation

Contour cultivation shortens slope length and slows runoff, conservation tillage maintains residue cover to protect the surface, and grassed waterways safely convey concentrated flow. Together these reduce both sheet and rill erosion.

Question 10Agricultural Engineering

The term 'field capacity' in soil water management refers to:

  1. Water absorbed by the crop during one day
  2. Water retained after excess gravitational water has drained Correct answer.
  3. Water remaining at the permanent wilting point
  4. Water held in the soil at saturation

Explanation

Field capacity is the moisture content reached after a saturated soil has drained freely for about two to three days, when matric tension is roughly 0.01 to 0.03 MPa. It represents the upper limit of readily available water for most crops.

Question 11Agricultural Engineering

In a combine harvester, excessive cylinder speed with too little concave clearance most likely causes which grain damage pattern?

  1. Whole grain with excessive straw in the tank
  2. Uniform grain with no visible damage
  3. Cracked and broken kernels with high fines Correct answer.
  4. Wet grain with high moisture content

Explanation

High cylinder speed and tight concave clearance increase impact and rubbing energy, which cracks kernels and produces fines. The correct setting balances threshing completeness against grain damage and is checked by inspecting the grain sample.

Question 12Agricultural Engineering

Which of the following best defines the 'lower heating value' of a fuel such as diesel used in farm engines?

  1. The ignition temperature of the fuel
  2. Heat released when all product water is condensed
  3. Heat released when water vapour in the products remains uncondensed Correct answer.
  4. The octane rating of the fuel

Explanation

Lower heating value excludes the latent heat of vaporisation of water in the combustion products, so it is lower than the higher heating value. Engine efficiency calculations normally use the lower heating value because exhaust water leaves as vapour.

Question 13Agricultural Engineering

A tractor engine develops 60 kW at the flywheel. If the transmission and driveline efficiency is 85 percent, what power reaches the drive wheels?

  1. 51 kW Correct answer.
  2. 70.6 kW
  3. 9 kW
  4. 60 kW

Explanation

Drawbar or wheel power equals engine power multiplied by driveline efficiency, so 60 × 0.85 = 51 kW. The remaining 9 kW is lost as heat and noise in the transmission and final drives.

Question 14Agricultural Engineering

In drip irrigation, emitters are rated at 4 L/h and spaced 0.5 m along a lateral, with laterals spaced 1.0 m. What is the average application rate per unit field area?

  1. 8 mm/h Correct answer.
  2. 4 mm/h
  3. 2 mm/h
  4. 16 mm/h

Explanation

Emitter discharge per unit area equals emitter flow divided by the product of emitter spacing and lateral spacing, giving 4 L/h ÷ (0.5 m × 1.0 m) = 8 L/h per m², which equals 8 mm/h. This assumes uniform emission and no losses.

Question 15Agricultural Engineering

A mouldboard plough's suction refers to which geometric feature?

  1. The tendency of the plough to pull sideways into unploughed land Correct answer.
  2. The vertical clearance beneath the share
  3. The length of the mouldboard
  4. The angle between share and landside

Explanation

Suction is the offset of the share and mouldboard towards the furrow wall, creating a lateral force that keeps the plough pressed against the unploughed land. Vertical suction is the downward or upward offset that helps penetration.

Question 16Agricultural Engineering

Why is a differential lock useful on a tractor working in a wet, slippery field?

  1. It forces both rear wheels to turn together, improving traction Correct answer.
  2. It reduces engine speed to save fuel
  3. It disengages the front axle to prevent wheel slip
  4. It increases hydraulic flow to the hitch

Explanation

A differential normally allows wheels to turn at different speeds, so a slipping wheel takes all the torque. Locking the differential couples both half-shafts so torque is shared and the wheel with grip can pull. It should be disengaged before turning on firm ground.

Question 17Agricultural Engineering

A grain storage bin holds wheat at 14 percent moisture. Which practice best prevents mould growth during storage?

  1. Sealing the bin immediately after filling without ventilation
  2. Storing at higher moisture to avoid kernel breakage
  3. Aerating the grain to keep it cool and below the safe moisture limit Correct answer.
  4. Adding water to reduce dust during handling

Explanation

Mould growth requires adequate moisture and warm temperatures, so keeping grain below the safe storage moisture and cooling it by aeration limits fungal activity. Wheat at 14 percent moisture is near the safe limit and needs prompt cooling.

Question 18Agricultural Engineering

In a hammer mill used for grinding feed grain, what mainly determines the fineness of the ground product?

  1. Diameter of the drive pulley
  2. Number of hammers only
  3. Hopper capacity and feed gate width
  4. Screen hole size and rotor speed Correct answer.

Explanation

Particles leave the grinding chamber only after passing the screen, so screen perforation size sets the upper particle size. Rotor speed and hammer tip speed influence the degree of breakage and throughput. Hopper and pulley dimensions affect capacity, not fineness.

Question 19Agricultural Engineering

A centre-pivot irrigation system has a wetted radius equal to its length. If the pivot length is 400 m, what area is irrigated?

  1. About 50 ha Correct answer.
  2. About 25 ha
  3. About 12.5 ha
  4. About 100 ha

Explanation

The irrigated area of a full circle is π times the radius squared, so π × 400² ≈ 502,655 m², which is about 50 ha. The pivot length acts as the radius from the central tower.

Question 20Agricultural Engineering

Which statement correctly describes the relationship between brake specific fuel consumption and engine efficiency?

  1. Lower brake specific fuel consumption indicates higher efficiency Correct answer.
  2. Lower brake specific fuel consumption indicates lower efficiency
  3. Brake specific fuel consumption is independent of efficiency
  4. Brake specific fuel consumption equals thermal efficiency

Explanation

Brake specific fuel consumption is the fuel mass used per unit of brake power produced, so a smaller value means less fuel per kilowatt-hour and therefore higher efficiency. It is inversely related to brake thermal efficiency through the fuel energy content.

Question 21Agricultural Engineering

In a ploughing operation, the draught of a mouldboard plough is most strongly influenced by which soil property?

  1. Soil pH
  2. Soil texture and moisture content Correct answer.
  3. Soil organic matter colour
  4. Soil colour

Explanation

Draught rises with finer texture and with moisture content away from the friable range, because cohesion and adhesion increase. Soil colour and pH have little direct effect on the mechanical resistance to tillage.

Question 22Agricultural Engineering

Which sensor principle is commonly used in a variable-rate fertilizer applicator to measure ground speed for rate control?

  1. Leaf wetness sensor
  2. Soil moisture probe
  3. Radar or wheel-mounted speed sensor Correct answer.
  4. pH electrode

Explanation

Variable-rate controllers need ground speed to adjust metering rate so that the target application rate per hectare is maintained. Radar or wheel-driven speed sensors provide this signal to the controller. Moisture, wetness and pH sensors measure different variables.

Question 23Agricultural Engineering

A sprayer has a 400 L tank and applies 200 L/ha. How many hectares can be covered with one tank?

  1. 20 ha
  2. 4 ha
  3. 2 ha Correct answer.
  4. 0.5 ha

Explanation

Area covered equals tank volume divided by application rate, so 400 L ÷ 200 L/ha = 2 ha. This assumes the sprayer is completely emptied and the rate is uniform.

Question 24Agricultural Engineering

In a four-stroke diesel engine, which sequence correctly describes the strokes?

  1. Intake, compression, power, exhaust Correct answer.
  2. Compression, intake, power, exhaust
  3. Intake, power, compression, exhaust
  4. Power, intake, compression, exhaust

Explanation

The four-stroke cycle runs intake of air, compression raising temperature, power after fuel injection and ignition, then exhaust of burned gases. Diesel engines draw air rather than a fuel-air mixture during intake.

Question 25Agricultural Engineering

A farm uses a 10 kW solar pump to lift water through a total head of 25 m. Assuming a pump efficiency of 60 percent, what approximate discharge can be expected?

  1. 24 L/s Correct answer.
  2. 2.4 L/s
  3. 40 L/s
  4. 10 L/s

Explanation

Useful hydraulic power equals input power times efficiency, so 10 kW × 0.60 = 6 kW. Discharge is power divided by density × g × head, giving 6000 ÷ (1000 × 9.81 × 25) ≈ 0.0245 m³/s, about 24 L/s.

Question 26Agricultural Engineering

In a combine harvester, what is the main function of the straw walkers located behind the threshing concave?

  1. To cut and chop the straw into short lengths before it leaves the machine
  2. To separate remaining grain from the straw mat by agitation and gravity Correct answer.
  3. To regulate the speed of the cleaning fan according to crop moisture
  4. To pre-thresh the crop before it reaches the cylinder

Explanation

Straw walkers carry the straw mat rearward over oscillating steps, so loose grain and chaff fall through the walker grates and are collected on the grain pan. Their role is separation after threshing, not cutting, fan control, or pre-threshing.

Question 27Agricultural Engineering

Which soil condition makes a mouldboard plough produce a poor, cloddy furrow slice that does not invert cleanly?

  1. Soil at a moisture content well below the plastic limit, when it is dry and hard Correct answer.
  2. Soil with a high proportion of well-decomposed organic matter
  3. Soil at a moisture content near the plastic limit, when it is friable
  4. Soil that has been loosened by a previous shallow cultivation pass

Explanation

Mouldboard ploughing relies on the furrow slice bending and turning over the mouldboard, which works best when soil is friable near its plastic limit. Very dry, hard soil cracks and breaks into clods instead of flowing over the board, leaving an uneven, poorly inverted surface.

Question 28Agricultural Engineering

A centrifugal pump is used to move irrigation water from a canal. If the discharge is throttled on the delivery side while the pump speed stays constant, what happens to the pump head and power requirement?

  1. Head decreases and power increases, following the pump characteristic curve
  2. Both head and power remain exactly constant
  3. Head increases and power decreases, following the pump characteristic curve Correct answer.
  4. Both head and power increase proportionally with discharge

Explanation

Along the characteristic curve of a centrifugal pump, reducing discharge by throttling moves the operating point to a higher head and a lower power draw. This is why throttling a centrifugal pump is a safe way to reduce flow, unlike throttling a positive-displacement pump.

Question 29Agricultural Engineering

A seed drill is calibrated and found to be delivering 20 percent more seed than the target rate per hectare. If the metering is driven by a ground wheel and the drive ratio is adjustable, what is the most direct correction?

  1. Reduce the metering drive ratio so the metering unit turns more slowly per ground-wheel revolution Correct answer.
  2. Decrease the working width of the drill by removing outer coulters
  3. Increase the forward speed of the tractor while keeping the drive ratio unchanged
  4. Increase the fan speed of the seed delivery air stream

Explanation

Seed rate per hectare depends on the volume metered per ground-wheel revolution, so reducing the drive ratio lowers delivery per unit distance travelled. Tractor speed changes do not alter the rate per hectare when metering is ground-driven, and air speed affects transport rather than metering.

Question 30Agricultural Engineering

In a flat-fan nozzle sprayer, which factor most directly controls the spray droplet spectrum and drift potential at a fixed pressure?

  1. The colour of the nozzle body
  2. The length of the boom section
  3. The nozzle orifice size and the spray angle rating Correct answer.
  4. The tank agitation rate

Explanation

Nozzle orifice size and spray angle determine flow rate and the droplet size spectrum, which in turn govern drift potential at a given pressure. Larger orifices and wider angles generally produce coarser sprays with less drift, while finer sprays increase drift risk.

Question 31Agricultural Engineering

A tractor is fitted with a three-point hitch using draft sensing. When the implement encounters a sudden increase in soil resistance, what does the draft control system do?

  1. It locks the hitch in position until the operator reacts
  2. It increases engine speed automatically to maintain forward speed
  3. It raises the implement slightly to reduce draft and then lowers it again as resistance falls Correct answer.
  4. It reduces hydraulic oil pressure to the lift cylinder to soften the ride

Explanation

Draft control senses the increased pull on the lower links and signals the hydraulic system to raise the implement, reducing working depth and draft. As resistance falls, the implement is lowered back, giving automatic depth adjustment on variable soils.

Question 32Agricultural Engineering

Which statement correctly describes the purpose of a tailings return in a combine harvester?

  1. It cools the engine radiator using the cleaning fan air stream
  2. It spreads chaff and straw evenly behind the machine
  3. It discharges clean grain into the grain tank by air pressure
  4. It returns partly threshed material from the cleaning shoe back to the threshing unit for reworking Correct answer.

Explanation

Tailings are the unthreshed heads and partly threshed material that pass over the cleaning shoe. Returning them to the cylinder or a separate rethresher recovers grain that would otherwise be lost and prevents tailings from accumulating.

Question 33Agricultural Engineering

A grain dryer uses heated air at a fixed temperature. If the airflow rate through the grain bed is doubled while the air temperature is unchanged, what is the most likely effect on drying?

  1. Drying rate decreases because the grain is cooled too quickly
  2. Drying rate increases, but the air leaves with a lower temperature rise and less saturated Correct answer.
  3. Drying rate stays the same because temperature is unchanged
  4. Drying rate increases and the exhaust air becomes fully saturated

Explanation

Higher airflow supplies more energy and removes moisture-laden air faster, so drying rate rises. Because each unit mass of air picks up less moisture and gives up less sensible heat, the exhaust air is cooler and less saturated than at low airflow.

Question 34Agricultural Engineering

In an engine, what does the compression ratio of a diesel engine primarily influence?

  1. The thermal efficiency and the ignition quality of the compressed charge Correct answer.
  2. The colour of the exhaust smoke only
  3. The lubricating oil viscosity required
  4. The battery charging voltage

Explanation

Compression ratio sets the temperature and pressure reached at the end of compression, which governs thermal efficiency and ensures the fuel ignites spontaneously. Higher ratios generally raise efficiency but also increase peak cylinder pressure and NOx formation.

Question 35Agricultural Engineering

A farmer wants to compare two tractors for fuel economy during ploughing. Which measure gives the most meaningful comparison of engine efficiency independent of load size?

  1. Brake specific fuel consumption expressed in grams per kilowatt-hour Correct answer.
  2. Fuel tank capacity in litres
  3. Total fuel used per day of ploughing
  4. Engine displacement in litres

Explanation

Brake specific fuel consumption normalises fuel use by the power produced, so engines of different sizes can be compared fairly. Total daily fuel depends on workload and hours, tank capacity is a storage figure, and displacement indicates size rather than efficiency.

Question 36Agricultural Engineering

Which practice best reduces drift when applying a herbicide with a boom sprayer on a windy day?

  1. Removing the outer boom sections to shorten the boom
  2. Increasing pressure to produce finer droplets that settle faster
  3. Raising the boom height to improve coverage
  4. Using lower pressure with larger-orifice nozzles and a coarse spray quality Correct answer.

Explanation

Drift is dominated by fine droplets that remain airborne, so lowering pressure and using larger orifices to produce coarser droplets reduces the fine fraction. Lower boom height and shielded or air-induction nozzles further limit drift.

Question 37Agricultural Engineering

A centre-pivot system applies water at a rate that exceeds the soil infiltration rate. What is the most likely consequence?

  1. Runoff and ponding, with uneven water distribution down the field Correct answer.
  2. Increased wetted radius of each sprinkler
  3. Improved uniformity because water spreads laterally
  4. Reduced evaporation losses from the soil surface

Explanation

When application rate exceeds infiltration, water cannot enter the soil as fast as it arrives, so it ponds and runs off. Runoff carries water downslope, causing over-application at the low end and under-application where it originated.

Question 38Agricultural Engineering

In a solar-powered irrigation pump, what is the main reason a storage tank is often included between the pump and the field distribution system?

  1. To raise the pressure at the drip emitters
  2. To buffer the mismatch between variable solar output and the water demand pattern Correct answer.
  3. To replace the need for a pump controller
  4. To increase the total pumping head available to the system

Explanation

Solar output varies through the day and with cloud cover, while irrigation demand may be steady or timed for other hours. A storage tank decouples supply from demand, allowing the pump to run when energy is available and water to be delivered when needed.

Question 39Agricultural Engineering

Which factor most strongly determines the draught requirement of a disc harrow working in a given soil?

  1. Diameter of the hydraulic hoses
  2. Number of grease nipples on the bearings
  3. Working depth and forward speed Correct answer.
  4. Colour of the disc blades

Explanation

Draught rises with the depth of soil engaged and with forward speed, because both increase the volume and rate of soil disturbance. Disc geometry and soil condition also matter, but depth and speed are the operator-controlled variables with the largest effect.

Question 40Agricultural Engineering

A four-wheel tractor has a wheelbase of 2.4 m and its centre of gravity is 1.0 m ahead of the rear axle. What approximate share of the tractor weight is carried by the rear axle when standing on level ground?

  1. About 75 percent
  2. About 50 percent
  3. About 42 percent
  4. About 58 percent Correct answer.

Explanation

Taking moments about the front axle, the rear axle load fraction equals the distance from the front axle to the centre of gravity divided by the wheelbase. The front axle is 2.4 m from the rear, the centre of gravity is 1.4 m behind the front axle, so 1.4/2.4 gives about 58 percent on the rear axle.

Question 41Agricultural Engineering

Which of the following is the main reason for using a pre-cleaner or cyclone ahead of the air filter on a tractor working in dusty field conditions?

  1. To cool the intake air before it enters the engine
  2. To increase the compression ratio of the engine
  3. To remove a large share of coarse dust before it reaches the main filter element Correct answer.
  4. To reduce the engine oil consumption

Explanation

A pre-cleaner uses centrifugal action or baffles to eject coarse dust before the air reaches the paper element, extending filter life and reducing restriction. It does not cool the charge, change compression ratio, or affect oil consumption directly.

Question 42Agricultural Engineering

In a grain storage silo, which combination of conditions most favours insect and mould development?

  1. Grain stored in a sealed, gas-tight structure with controlled atmosphere
  2. Warm grain at high moisture with poor aeration Correct answer.
  3. Grain cooled to below 15 degrees Celsius with low moisture
  4. Cool, dry grain with regular aeration

Explanation

Moulds and storage insects thrive when grain is warm and moist, and poor aeration lets heat and moisture accumulate in pockets. Cooling the grain and keeping moisture low, or using sealed controlled-atmosphere storage, suppresses both hazards.

Question 43Agricultural Engineering

A hammer mill is fitted with a screen having smaller perforations. Assuming the same rotor speed and feed rate, what is the expected effect on the ground product and the mill?

  1. No change in fineness but lower power draw
  2. Coarser product with higher throughput
  3. Finer product with higher throughput and lower power draw
  4. Finer product, lower throughput, and higher specific energy per tonne Correct answer.

Explanation

Smaller screen openings retain particles longer and limit the rate at which ground material can exit, so the product is finer. Throughput falls and the energy required per tonne rises because more size reduction work is done per unit mass.

Question 44Agricultural Engineering

Which statement correctly describes the role of the thermostat in a tractor engine cooling system?

  1. It monitors coolant level and warns the operator
  2. It regulates coolant flow to the radiator to maintain a stable operating temperature Correct answer.
  3. It adjusts the ignition timing as the engine warms up
  4. It controls the speed of the cooling fan according to engine load

Explanation

The thermostat is a temperature-sensitive valve that opens as coolant warms, allowing flow to the radiator, and closes when the engine is cold to speed warm-up. It does not drive the fan, sense coolant level, or control ignition timing.

Question 45Agricultural Engineering

A boom sprayer has nozzles spaced 0.5 m apart on the boom. If each nozzle delivers 1.2 L/min and the sprayer travels at 6 km/h, what is the approximate application rate?

  1. 120 L/ha
  2. 240 L/ha Correct answer.
  3. 60 L/ha
  4. 480 L/ha

Explanation

Application rate equals nozzle flow divided by the area covered per unit time per nozzle. At 6 km/h the sprayer covers 6000 m per hour, so each 0.5 m nozzle strip covers 3000 square metres per hour; 1.2 L/min is 72 L/h, and 72/0.3 ha gives about 240 L/ha.

Question 46Agricultural Engineering

In a ploughing operation, what is the purpose of the landside on a mouldboard plough?

  1. To cut the furrow slice vertically ahead of the share
  2. To adjust the working depth of the plough
  3. To resist the side thrust created by the mouldboard and keep the plough running straight Correct answer.
  4. To pulverise clods behind the mouldboard

Explanation

The mouldboard pushes the plough sideways as it inverts the furrow slice, and the landside bears against the furrow wall to resist that thrust. This keeps the plough tracking straight and maintains a uniform furrow width.

Question 47Agricultural Engineering

A farmer must choose between a drag hose and a hard hose reel irrigator for a field with a long, narrow shape and a single water source at one end. Which factor most favours the hard hose reel machine?

  1. It requires no water pressure to operate
  2. It works only on flat land with no wheel tracks
  3. It can travel long distances along a lane while irrigating a strip, reducing the number of moves Correct answer.
  4. It applies water without any sprinkler head

Explanation

A hard hose reel machine pulls itself along a lane while the sprinkler operates, covering a long strip from a single hydrant. This suits long narrow fields because fewer relocations of the machine are needed compared with hand-moved systems.

Question 48Agricultural Engineering

What is the main agronomic purpose of a roller-crimper used in conservation agriculture?

  1. To incorporate crop residues into the topsoil
  2. To break surface crusts after rainfall
  3. To flatten and crimp a cover crop so it forms a mulch that suppresses weeds Correct answer.
  4. To compact the subsoil to improve trafficability

Explanation

A roller-crimper bends and crimps standing cover crop stems, killing the cover and leaving it as a surface mulch. The mulch protects the soil and suppresses weeds, which is central to no-till and organic conservation systems.

Question 49Agricultural Engineering

A tractor tyre is operated at too high an inflation pressure for its load. What is the most likely consequence in field work?

  1. Increased traction because the tyre is stiffer
  2. Reduced tyre footprint and increased soil compaction in the wheel tracks Correct answer.
  3. Improved flotation on soft, wet soil
  4. Lower fuel consumption due to reduced rolling resistance

Explanation

Over-inflation stiffens the casing and reduces the contact area, so the same load is carried on a smaller footprint and contact pressure rises. This increases rutting and subsurface compaction and reduces traction in soft soil.

Question 50Agricultural Engineering

Which of the following best explains why a combine harvester's cleaning shoe uses a fan and oscillating sieves together?

  1. The sieves drive the fan through a mechanical linkage
  2. The fan cools the sieves to prevent overheating during harvest
  3. The fan provides an air stream that lifts light chaff while the sieves stratify grain and chaff by size and density Correct answer.
  4. The fan presses grain through the sieves while the chaff stays on top

Explanation

The cleaning shoe combines two separation principles: sieves stratify material by size and density, and the fan air stream carries light chaff rearward while heavier grain falls through. Together they clean grain with minimal loss.