Agricultural Engineering and Farm Machinery
Agricultural Engineering and Farm Machinery covers tillage implements, sowing and threshing machines, tractor power, irrigation systems and field-capacity calculations.
Tillage and implements
- Primary tillage: mouldboard plough, disc plough - inverts soil, buries residues.
- Secondary tillage: disc harrow, cultivator, leveller - pulverises and levels the seedbed.
- Sowing: seed drill for line sowing, planter for bold seeds, rotavator for combined tillage and puddling.
- Threshing: thresher, combine harvester.
Power and irrigation
1 hp = 0.746 kW. Tractor power reaches implements through the PTO and three-point hitch. Drip irrigation saves about 40–60% water compared with flood irrigation and suits wide-row crops and orchards; sprinkler irrigation suits close-grown crops and undulating land.
Field capacity formula
Theoretical field capacity (ha/h) = (width in m × speed in km/h) ÷ 10. Effective field capacity = theoretical × field efficiency.
Worked example
A 2 m seed drill runs at 5 km/h with 75% field efficiency. Theoretical capacity = (2 × 5) ÷ 10 = 1.0 ha/h. Effective capacity = 1.0 × 0.75 = 0.75 ha/h. Time to cover 4 ha = 4 ÷ 0.75 = 5.33 hours. Reasoning: the machine only works productively for three-quarters of the time because of turns and refilling.
Traps that cost marks
Using the divisor 100 instead of 10; forgetting to multiply by field efficiency; mixing primary and secondary implements; quoting kW when the question asks for hp.