PEC EPE Agricultural flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

PTO standard speed

Power take-off shaft speed defined by standard, commonly 540 rpm or 1000 rpm, allowing implements to be matched to tractor engine speed and gearing.

Drawbar power formula

Drawbar power in kilowatts equals draft force in kilonewtons multiplied by forward speed in metres per second. It excludes power lost to wheel slip and rolling resistance.

Wheel slip percentage

Slip equals the difference between no-load and loaded travel distance divided by no-load distance, expressed as a percent. Field target is roughly 8 to 15 percent.

Draft of tillage tool

The horizontal force a soil-engaging implement exerts against the tractor. It rises with depth, width, soil strength and speed, and determines required drawbar power.

Seed rate calibration

Procedure of turning the metering unit a known number of revolutions, weighing the seed delivered, and converting to kilograms per hectare using the effective wheel circumference.

Sprayer application rate

Litres per hectare equals nozzle flow in litres per minute times 600, divided by the product of nozzle spacing in metres and speed in kilometres per hour.

Nozzle flow and pressure

Nozzle flow varies with the square root of operating pressure. Doubling pressure increases flow by about 41 percent, so pressure alone is a coarse rate control.

Reference evapotranspiration

ET0 estimates water loss from a reference grass surface using weather data such as radiation, temperature, humidity and wind, commonly via the Penman-Monteith method.

Crop coefficient Kc

A dimensionless factor multiplying reference evapotranspiration to estimate actual crop water use at a given growth stage. Values change through the season.

Drip irrigation efficiency

The fraction of applied water available to the crop. Drip typically reaches 85 to 95 percent, compared with roughly 50 to 70 percent for furrow systems.

Field capacity moisture

The water content remaining in soil after free drainage has largely ceased. Traffic on soil near field capacity causes the greatest compaction damage.

Soil compaction indicators

High axle loads and high tyre inflation pressure increase compaction risk. Low inflation pressure and wide tyres spread load and reduce surface damage.

Grain safe storage moisture

Moisture content below which grain can be stored without mould growth at ambient temperature, about 13 to 14 percent for wheat and maize.

Grain drying airflow

The rate of air passed through a grain bulk, usually in cubic metres per minute per tonne. Higher airflow permits faster moisture removal and deeper drying fronts.

Three-point hitch categories

Standardised linkage sizes, Category I to IV, differing in pin diameter and lift capacity, ensuring compatible mounting of implements on tractors of different power classes.

Tractor power-to-weight ratio

Mass per unit of engine or PTO power. Field work commonly targets about 25 to 35 kilograms per kilowatt to balance traction and fuel use.

Mouldboard plough function

A primary tillage tool that inverts and pulverises soil to bury residue and loosen compacted layers, typically working to 20 to 30 centimetres depth.

Disc harrow action

A secondary tillage implement using concave discs to cut, mix and level soil and residue. Disc angle and spacing control aggressiveness and clod size.

Seed drill metering types

Mechanisms that meter seed at a controlled rate, including fluted rollers, studded rollers and belt metering, matched to seed size and desired population.

Combine harvester threshing

Separation of grain from straw and chaff by a rotating cylinder or rotor against a concave, followed by sieving and cleaning before grain enters the tank.

Grain header loss

Grain lost at the cutting front before entering the machine, influenced by reel speed, ground speed, header height and crop condition.

Baler twine and net wrap

Binding materials used to hold round or rectangular bales. Net wrap speeds baling and sheds water better than twine on round bales.

Spray drift reduction

Lowering drift by using larger droplets, lower boom height, lower pressure, air-induction nozzles and spraying in low wind, typically below about 15 kilometres per hour.

Boom height for spraying

Nozzle-to-target distance, usually 40 to 50 centimetres for flat fan nozzles. Excessive height widens the pattern and increases drift risk.

Sprayer tank mixing order

Sequence for adding products to water, generally water conditioners first, then granules, wettable powders, suspension concentrates, emulsifiable concentrates and finally adjuvants.

Tractor hydraulic flow

The volume of oil delivered per minute by the tractor's hydraulic pump, determining how quickly implement cylinders and motors can operate.

Diesel engine torque backup

The increase in torque from rated to maximum torque as engine speed falls, giving a tractor resistance to stalling under sudden load.

Rolling resistance

The force resisting forward motion from tyre deformation and soil deflection. It rises with soil softness, tyre load and lower inflation pressure.

Traction efficiency

The ratio of drawbar power to axle power, reduced by wheel slip and rolling resistance. It is highest on firm soil with appropriate ballast.

Irrigation scheduling

Deciding when and how much to irrigate using soil moisture, evapotranspiration estimates or crop stress indicators to avoid both deficit and overwatering.

Furrow irrigation losses

Water lost to deep percolation, runoff and uneven distribution in furrow systems, giving application efficiencies typically around 50 to 70 percent.

Sprinkler uniformity

Evenness of water distribution across a sprinkler pattern, described by the coefficient of uniformity; higher values reduce over- and under-watered zones.

Grain moisture meter

An instrument estimating grain water content, commonly by electrical capacitance or resistance, needing calibration against oven-dry reference methods.