Cutting edge technology cuts irrigation costs

Cutting edge technology and improved water management practices have enabled sugarcane farmers Johan and Cobus Horn to cut irrigation production costs by up to 30% and by 2021 they would have added a further 60 “vertical” hectares to their 300ha farm outside Pongola.

Cobus said the recent drought and the expansion by commercial farmers had forced him to re-think his management and farming practices to make the hectares available to him work harder and at a reduced cost.

The father and son partnership started converting their sugarcane operation from flood and sprinkler irrigation to drip irrigation four years ago.

“The challenge we have here is land is very expensive,” said Cobus.

“The bigger sized farmers can afford to buy land more easily through economies of scale. I am surrounded by other commercial farmers so I had to make a plan to grow my farm vertically. I had to make a way to produce more tons per hectare without sacrificing sucrose content. With rising input costs, particularly the cost of electricity, I also had to find a way to spend less money per hectare.”

The move to install the drip system, said Cobus, resulted in a 30% reduction in electricity usage and an exponential return on the multi-million rand investment after just 24 months.

He said the irrigation system had also allowed them to sustainably use a mix of soil types, ranging from shale to red loam.

“The variety we prefer to plant is N53 because it is one of the few varieties that has high sucrose content even if pushed for higher tonnages. The only limitation is it needs good soils. I have all kinds of soils here, from pure shale to sand to red loam. But drip irrigation has allowed us to schedule even in rocky soils and get good returns.”

Furthermore, the drip irrigation scheme helped them survive one of the worst droughts in living memory. “Honestly, we wouldn’t have managed if we hadn’t had the drip irrigation. We were able to use the reduced water quotas from the dam more effectively,” he said.

Water from the Bivane Dam which is managed by the Impala Water Users Board and used to irrigate sugarcane and fruit farms around Pongola and provide water to the town, was at a historical low at the height of the drought last year holding just 10% of its capacity. “The water restrictions were severe. We only got water for one week every three weeks.”

On why more farmers had not converted to drip irrigation in the past, Cobus said he believed it was because the system was management intensive. “But now we have cutting edge technology. We are using probes in the field to measure water and moisture content. There are trials underway at the moment using Canesim* together with the probes. I like to use both the probes and Canesim because then I can adjust according to the readings I am getting from the probes.”

Regardless of the technology that relayed real time data to his mobile phone and his desktop computer, the father of three said it was essential to keep “the dirt under my feet” if the system was to work efficiently. “We flush each block once a week. It’s no good just sitting in your office and thinking technology will do the work for you. You have to keep an eye on everything all the time,” he said.

Canegrowers Area Manager in Pongola Theuns Theunissen said drip irrigation was also one of the most effective when it came to saving water.

He said semi-permanent overhead sprinklers were between 70% to 83% water use efficient, while a centre pivot system ranged between 80% and 90%. Surface flooding using earth canals was the least efficient at between 60% and 86% with sub-surface drip infrastructure the most efficient at between 90% and 95%.

The cost of the water to farmers who use the canal system from the Bivane Dam is R2 198 a hectare, inclusive of a R1 098 dam and canal system maintenance and management fee.

Cobus said he stumbled on the drip system by chance. “It’s quite a funny story. A nearby farm came up for sale. It was producing something like 50 tons a hectare but land for sale is scarce here. The layout was not suitable for pivot irrigation. I discussed it with my dad and we decided to install drip irrigation. Last year we harvested 200 tons a hectare from one of our fields under drip and that was in one of the worst droughts in living memory.”

In comparison, Cobus said some of the fields that were still under sprinkler and flood irrigation had dropped to as little as 38 and 45 tons-a-hectare.

“It was really bad. We also spent a lot on drilling and re-covering existing boreholes so we could keep going,” he said.

Cobus anticipated that by 2021 all 272ha under sugarcane (the remainder are planted to pecan and macadamia nuts) would have been converted to drip irrigation. “Because of the capital outlay it is just not practical to rip up your whole farm all at once.

“I am busy with an eight-year development phase. I am now on year four. I don’t think my method is perfect but what I am doing is dividing the fields up into 40ha blocks. I then plough them out, re-do the whole pump house, install a new pump and the whole main pipeline. As a result I have some fields that are giving me very high yields while the old fields give me very low yields. But as I am putting in the drip irrigation I am keeping everything behind me clean and clear and then what is in front of me, I do whatever I can to keep them going. There are some fields though that are going on for 15 ratoons now.”

Excluding the cost of new pump house infrastructure, the development had cost R43 000 a hectare including the installations inside the pump house, automatic filter banks, irrigation controllers, pump motors, the main pipe line and side laterals and the sub-surface drips or emitters and subsurface drip lines.

Three of the new pump houses were also fitted with storage tanks so that liquid fertilisers could be added to the water system creating a cost-effective fertigation programme.

Cobus said improved design and planning had meant he was able to introduce better harvesting practices. “The fields are designed now for controlled traffic, I am using a Slew loader. That means a tractor isn’t going over them during harvesting so we get better stool longevity. I am hoping to get at least 15 years from these new fields,” he said.

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