Agricultural Engineering, Mechanisation and Farm Structures
This domain covers machinery, calibration, water and structures. Expect calculations on sprayer or planter output and questions on matching implements to tractors and designing safe, functional farm facilities.
Core rules
- Tractor power must match implement width and soil conditions; a wider implement needs more power. PTO-driven machinery runs at standard 540 rpm.
- Primary tillage includes mouldboard ploughing and ripping; secondary tillage includes discing and harrowing. Conservation tillage reduces passes and residue loss.
- Calibrate sprayers and planters before use. For a boom sprayer, litres per hectare = (nozzle output in L/min x 600) divided by (speed in km/h x nozzle spacing in metres).
- Farm structures include stores, kraals, crush pens, dip tanks, silos, fences and water troughs. Design them for animal flow, drainage, shade and safety.
- Irrigation systems include drip, sprinkler and furrow; schedule irrigation from crop water need and soil moisture, not habit.
- Safety requires PTO guards, jack stands, chemical protective equipment and secure guards on moving parts.
Worked example
A boom sprayer has nozzles delivering 1.2 L/min, spaced 0.5 m apart, and operates at 6 km/h. Application rate = (1.2 x 600)/(6 x 0.5) = 720/3 = 240 L/ha. The reasoning uses the standard formula, keeping speed in km/h and spacing in metres. To apply 240 L/ha over 5 ha, the sprayer must deliver 1 200 L. Check each nozzle, not just one, and avoid overlap.
Traps
- Mixing centimetres and metres in the calibration formula.
- Using boom width instead of nozzle spacing.
- Running a PTO implement at the wrong speed.
- Designing a crush without an escape route or non-slip floor.
- Irrigating by schedule without checking soil moisture.