The NAMC’s recent assessment of escalating electricity tariffs on South African agriculture put a number to something most producers in the Free State and KwaZulu-Natal already feel every time they fill a tank or pay a monthly bill. Input costs are climbing faster than output prices. That squeeze changes which equipment decisions make financial sense, and it hits TMR feeding operations in a specific place: the time the tractor spends turning a PTO shaft.
Most operators think about diesel in litres per hundred kilometres, or maybe per hectare. Feed mixing operations rarely run that calculation per tonne of ration. They should be. The difference between a 12-minute batch and an 18-minute batch, run three times a day for 200 days, is not a rounding error.
How Extra Minutes Per Batch Multiply Diesel Costs Across a Season
A tractor running a vertical mixer under load sits roughly in the 8 to 15 litres per hour range depending on size and PTO demand. Call it 10 litres per hour for a mid-size unit on a well-matched machine, and higher when the ration is heavy or the auger is working against itself.
Add six minutes to every batch. That is 0.1 hours of additional PTO time per mix cycle. Three cycles a day gives 0.3 extra tractor hours. Over a 200-day winter-to-spring feeding season, that is 60 hours of unnecessary engine time. At 10 litres per hour, you have burned 600 extra litres. Price diesel in KwaZulu-Natal at current pump rates and that number converts to a real rand figure with no difficulty.
The problem compounds when the cause of long mix time is not ration complexity but equipment mismatch. A worn kicker plate, a generic auger sized for a different machine, or a two-stage gearbox straining under a heavy silage load all add minutes to every cycle without adding anything to mix quality. Those minutes are pure cost. For a deeper look at how kicker condition and sizing directly affect cycle time and fuel draw, this breakdown of kicker function and wear covers the mechanism in detail.
Capacity-Matched Augers and Faster Cutting Reduce Tractor Hours
The auger is where most of the PTO energy either gets used productively or gets wasted. A machine with an auger sized for its specific chamber volume pulls less torque to move the same material than one running a generic auger design stretched across multiple model sizes. Torque demand is the thing that burns fuel. Cut the torque demand and you cut the fuel bill, without changing ration size or feeding frequency.
Faster cutting matters too. A square-cutting knife arrangement that forces bales into a high-pressure zone near the auger base does two things at once: it shortens the time the bale spends as an unprocessed mass, and it reduces the number of auger revolutions needed to reach a uniform mix. Fewer revolutions, less fuel, same ration quality.
Gearbox design feeds into this directly. A three-stage planetary gearbox multiplies torque progressively across three stages, distributing load across more gear faces. A two-stage design concentrates that load. Under a heavy ration, the two-stage unit stresses the tractor’s PTO clutch and often forces the operator to slow the feeding process or split batches. Either outcome costs time, and time costs diesel.
LEO Agriculture builds capacity-specific augers into each machine size rather than fitting one geometry across a range. The three-to-four stage planetary gearboxes are standard fitment, not an upgrade. For operators comparing specifications ahead of a spring purchase, the engineering detail behind the Diamond auger geometry explains how knife placement and pressure zones translate to measurable time savings per batch.
A Simple Rand Per Tonne Worksheet
Running this calculation takes five figures. Most operators can pull them from memory or a fuel receipt.
- Tractor fuel consumption under PTO load — litres per hour. If you have not measured it, 10 L/hr is a reasonable working estimate for a 100 kW (134 hp) tractor at 75% load.
- Current diesel price at your nearest depot — rand per litre. Free State and KZN pump prices differ by a few cents but both reflect the same upward pressure from tariff adjustments.
- Actual mix time per batch — minutes. Time it with a phone for a week of normal rations. The number you think it is and the number it actually is often differ.
- Batch size in tonnes of mixed ration — this is your denominator.
- Batches per day and days per season — multiply these to get annual PTO hours.
The formula is straightforward. Divide litres per hour by 60 to get litres per minute. Multiply by mix time in minutes to get litres per batch. Multiply by your rand per litre price to get rand per batch. Divide by batch tonnage to get rand per tonne mixed.
Now run the same calculation with a mix time that is four minutes shorter. That gap is what a functioning, correctly sized kicker, a matched auger, and a competent gearbox are worth in fuel alone. It does not include saved knife wear, reduced PTO clutch stress, or the value of consistent ration uniformity on production outcomes.
What Changes When You Plan for Spring Now
Late winter is the point at which most purchasing decisions for the new feeding season get made. Dealers have lead times to manage. Fabrication slots fill early, particularly on larger HD series machines. If the fuel cost worksheet above reveals that your current machine is costing you R8 to R12 per tonne more than a well-specified replacement would, the case for acting now rather than carrying another season of inefficiency is straightforward arithmetic.
It is also worth thinking past the mixer itself. A ration that mixes well can still arrive at the bunk with quality compromised by the delivery process. What happens between the mixer and the bunk is an underappreciated source of waste, especially on operations where the delivery wagon is an afterthought.
The numbers most producers focus on at this time of year are commodity prices and rainfall forecasts. The diesel rand per tonne figure sits quietly in the background, accumulating batch by batch. It responds directly to the mechanical condition and specification of a single machine. That makes it one of the more controllable costs on the operation, which is a rare thing in the current input environment.
