Power Tiller or Mini Tractor for a 1.6 ha Farm
A young farmer in Theni district has 1.6 ha of irrigated land, two bullocks and a pair of hired labourers available at ₹600/day. Labour is increasingly scarce at peak tillage time. A custom-hiring tractor is available at ₹1,500/h, and a custom power tiller at ₹800/h. The farmer is offered an 8 hp power tiller for ₹1.8 lakh with a 40% subsidy, or a 20 hp mini tractor for ₹4.5 lakh with no subsidy. The power tiller would carry a 0.6 m rotavator at about 2.2 km/h with 75% field efficiency. The mini tractor would carry a 1.2 m rotavator at about 3.0 km/h with 80% field efficiency. The farm needs about 60 hours of tillage and spraying work a year. A three-phase electricity connection is already available for irrigation.
1. Calculate the effective field capacity and the time needed for one rotavator pass with each machine.
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Use: effective field capacity (ha/h) = (width in m × speed in km/h)/10 × field efficiency.
Power tiller:
- Width × speed = 0.6 × 2.2 = 1.32
- Divide by 10 = 0.132 ha/h at 100% efficiency
- Apply 75% efficiency: 0.132 × 0.75 = 0.099 ha/h, about 0.1 ha/h
- Time for 1.6 ha = 1.6/0.099 = 16.2 h per pass
Mini tractor:
- Width × speed = 1.2 × 3.0 = 3.6
- Divide by 10 = 0.36 ha/h at 100% efficiency
- Apply 80% efficiency: 0.36 × 0.80 = 0.288 ha/h
- Time for 1.6 ha = 1.6/0.288 = 5.6 h per pass
The mini tractor is about 2.9 times faster per pass. If two passes are needed, the power tiller takes about 32 h and the mini tractor about 11 h. These figures exclude turning time on small plots, which penalises the larger machine more.
2. Compare the annual ownership cost of each option with custom hiring, and recommend a machine strategy. State your assumptions.
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Assume a 10-year life, 10% salvage value, 10% interest on average investment, ₹3,000/year for shelter and insurance for the power tiller and ₹8,000 for the mini tractor, and variable costs of ₹250/h for the power tiller and ₹450/h for the mini tractor at 60 h/year.
Power tiller: subsidy 40% of ₹1,80,000 = ₹72,000, so net price = ₹1,08,000. Depreciation = (1,08,000 - 10,800)/10 = ₹9,720. Interest = (1,08,000 + 10,800)/2 × 0.10 = ₹5,940. Fixed cost = ₹9,720 + ₹5,940 + ₹3,000 = ₹18,660. Variable = 60 × ₹250 = ₹15,000. Total = ₹33,660/year, or about ₹561/h.
Mini tractor: depreciation = (4,50,000 - 45,000)/10 = ₹40,500. Interest = (4,50,000 + 45,000)/2 × 0.10 = ₹24,750. Fixed cost = ₹40,500 + ₹24,750 + ₹8,000 = ₹73,250. Variable = 60 × ₹450 = ₹27,000. Total = ₹1,00,250/year, or about ₹1,671/h. Break-even against custom tractor at ₹1,500/h is ₹73,250/(1,500 - 450) = about 70 h/year.
Recommendation: buy the subsidised power tiller for rotavation and spraying, and hire the custom tractor for heavy or deep tillage. The mini tractor is cheaper only above about 70 h/year, and this farm has about 60 h. Custom power tiller at ₹800/h is also more expensive than owning at this use level, but owning carries repair and breakdown risk.
3. What operational, safety and subsidy factors could change this recommendation?
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Operational factors: the power tiller is slow on 1.6 ha and causes operator fatigue; it cannot haul produce or run a thresher. If the farmer plans to expand to 3 ha, take up transport, or do custom work for neighbours, the mini tractor becomes viable because its fixed cost can be spread over more hours. Field shape also matters: small bunded plots reduce the advantage of a wider rotavator.
Safety factors: power tillers have exposed rotating tines, no cab, and high vibration; the operator needs training, guards and sturdy footwear. A mini tractor needs a certified ROPS or at least a strong frame, a guarded PTO shaft, and a trained operator. Neither machine should be used on public roads without the required lighting and registration.
Subsidy factors: the 40% subsidy may require the farmer to attend training, keep the machine for a minimum period, or allow custom hiring to other farmers. If custom hiring is a condition, the power tiller's low cost per hour becomes an advantage. If the subsidy is delayed, the cash-flow comparison changes.
Power connection: the three-phase connection supports irrigation pumps, not tillage, so it does not replace a machine. It may, however, make a stationary thresher or sprayer more attractive than a tractor-mounted unit.