Implementing new technology comes with steep learning curves and often initial results don’t bode well. This has been the case with mechanised harvesting in South Africa, but with continuous tweaking and adaption RCL FOODS has implemented sugar cane mechanisation with encouraging results. Yields are up, costs are down and operations are more efficient.

While countries like Brazil and Australia have been planting and harvesting mechanically for decades, the technology has had a bad rap in South Africa.

RCL FOODS themselves found that yield declines were the order of the day when they did mechanisation trials ten years ago.

However persistence paid off and through a process of trial and error they have ironed out the creases and today not only achieve yield improvements, but significant reductions in operating costs.

Hennie Greyling, cane operations manager at RCL FOODS’ Sugar & Milling division, said economics drove the company to persist in mechanisation.

“If the implementation is correct the yield is improved and you reduce water consumption by 10% – 18%. Furthermore the cane does not need to be burned, which has positive implications for soil health and less pressure from environmentalists.”

RCL currently mechanises 30% of the land they own and manage. They are aiming for 55% in five years’ time, which is the maximum that the area’s topography will allow.

“The Malelane/Komatipoort area is not overly flat and the machines can’t handle steep hills. This means there will still be 45% of our fields harvested by hand. This is a concern going forward as labour is becoming scarce. A lot can happen in five years and we are hoping over time technology could improve and will be able to harvest mechanically on the steep slopes,” He said.

Mechanical harvesting results in an increase in profit of 6%.

Implementing mechanisation

The first issue RCL hoped to solve with mechanised harvesting was the scarcity and productivity of labour. They replant 10% of their fields every year, equating to nearly 2000ha.

“There is a huge amount of cane that is tipped onto the field which must be cut and planted. Since we only have a limited time slot to get everything done before the rain starts, we started looking at planting mechanically to speed up the process. Since it wasn’t viable to plant mechanically and not harvest as well, we decided to investigate the whole production chain.”

A quick calculation found that mechanical harvesting cost R9 000 a hectare  while cutting by hand cost only R3000 a hectare.

But after three years of statistical trials, Greyling found the former results in an 80% reduction in energy cost, a 40% saving in transport costs and a 50% saving in seed cane. Furthermore the mechanical planter was three times faster than by hand and the cane germinated quicker.

“All of the other benefits aside, you are 6% better off financially planting and harvesting mechanically than manually,” said Greyling.

One of these benefits is the layer of mulch that is left in the fields after harvesting. Since the fields do not need to be burned, the leaves that the harvester throws out after taking in the cane is left on the land. This equates to around 15 tons a hectare of mulch which protects the soil and assists in retaining moisture. This means the farm is not only using less water, but also less electricity to run the irrigation systems.

However, Greyling said the fan speed of the harvester was one of the aspects that needed tweaking to optimise operations.

“When we started mechanising we had a 20 tonsa hectare  reduction in yield than cutting by hand. At that stage we were harvesting with a fan speed of 1 000 revolutions per minute (RPM), which blows much of the cane out with the leaves where it then forms part of the trash that stays behind on the field. We then lowered the fan speed to 550RPM. This means you take more trash to the mill but you have less cane losses. We then saw that we actually had 10 tons a hectare increase in yield compared to hand cutting.”

The leaves however still needed to be removed from the loads delivered to the mill so a trash separator was built that blows the leaves one side and cuts the cane into smaller billets, diverting it to another side. The mills prefer these shorter billets because it goes through the mills much easier and results in less wear and tear on the machines.

Greyling said this cane is clean and fresh because the time from harvest to mill is reduced to ten hours, from the 60 hours it takes to get the cane from the field to the mill with conventional harvesting. The quality and purity of the cane is better the fresher it is.

 

On the straight and narrow

Greyling says there is a perception that the yield decline is faster with mechanised harvesting. “In theory with conventional harvesting one would replant cane every ten years, and with mechanisation it is around six years because the harvester drives over each row, whereas conventional harvesting only requires a tractor to drive over every 6th row or so. This was another aspect we had to investigate.

“Before we mechanised we started seeing yield declines in normal rain seasons. Early and late in the season we would have downpours and would be forced to harvest in those wet conditions with a truck that weighs around 50 tons when fully loaded. The trucks get stuck and have to get pulled out and it would wreck the fields. We found that harvesting in these conditions resulted in having to replant the cane every six years anyway.”

“But with the addition of GPS technology the harvesting machines drive on straight lines, between the rows, never driving over the planted cane. When the field is planted it is also done according to GPS coordinates, so when it is harvested the machine follows the same route. In the old days you would have to harvest with your eyes and when the cane is grown you can’t see where the rows are so the tractors drove everywhere.

“If you plant the field correctly, you harvest it again without any trampling of the cane. And because the tractor is driving the same route, those areas where the machine moves compact and so it stays hard even when it is wet so the machines don’t get stuck. This means there is little damage should the fields be exceptionally wet. Now we have seen an increase in yields,” he said.

Hennie Greyling

Gains

RCL FOODS has achieved record yields this year, which is the first year they have harvested all of the mechanised areas. They have averaged 160 tons a hectare average, up from the 140 tons in a hectare previously. 

Greyling said there were many small but positive spin offs from mechanisation.

“After three years you can see a vast improvement in the soil because the mulch layer has started breaking down. This has resulted in a further saving of R700 a hectare in fertiliser costs. Then you save another R300 a hectare on weeding costs because the mulch layer supresses the weeds. There is less erosion too.

“While you plant you add the fertiliser and any chemicals like that for pineapple rot. So you are doing three things all at once. Because the lines are so straight due to the GPS you get better growth and coverage of the field. The growth is more even because it is all planted at the same time, unlike the conventional that takes longer so there is a big gap between the first and last ratoon that is planted.”

Greyling said sub surface irrigation systems were far more viable with mechanised planting and harvesting because the tractor drives on GPS so it doesn’t cross the field and ride over the irrigation pipes.

“The pipes are put below the cane where the machines don’t drive. We are now confident to go over to sub surface drip irrigation because we know our pipes won’t get damaged. So there is a further saving of 40% on the water due to the irrigation system,” he said.

Top tips for mechanisation

Farmers looking at mechanisation are faced with huge investment costs. To overcome this obstacle and give the farmer time to adjust to the new system, Greyling advised that mechanisation contractors be used. He offered further important points to consider:

  • Don’t do mechanical harvesting if you did not plant mechanically or there will be damage to the fields. The row spacing must be correct and the same GPS coordinates used when planting and harvesting.
  • Make sure the fan speed is correct. If it’s too fast too much cane will stay behind in the field.
  • Harvester blades must be disinfected when moving between the fields to prevent the spread of ratoon stunting disease (RSD).
  • Opt for a machine with tracks rather than wheels for a more stable machine.