THE CLIMATE KELPIE BLOG: Forecast information essential for sugarcane production

Posted by BCG on 28th September 2021

Tweed sugarcane grower Robert Quirk is a regular user of the BoM website and by regular we mean he checks the site as often as millennials check their Instagram account. Robert who owns and works an average-sized sugarcane farm (100ha) with his wife Margaret, needs to know rainfall, wind speed and direction by the hour.

Image 1: Robert is pictured in soybeans he grows a break crop. These beans are growing on rehabilitated acid sulphate scales, all the peat had been burned some years before. It had a surface ph of around 3 and salinity of half ocean water. Robert says it’s “now quite productive”.
Image 2: A sugar cane harvester cuts 1 – 8 metres at a time harvester, 700 to 1000 tonne per day.

“There are 10 of us who own one harvester which runs from June to November. We harvest 20 percent in rotation. Because there is so much rain about, knowing what the rain is doing by the hour is important so we can make the most of our time with the harvester. We also need to know when the rain is coming as many of our chemicals need rain within days and can only be applied in light breezes to avoid chemical drift,” explained Robert whose annual average rainfall is 1600mm. “So far this year we have recorded 1400mm so the rest of the year should be dry or we will exceed our average annual rainfall by quite a lot,” said Robert.

“Hourly rain and wind forecasts including wind direction and speed are particularly important when the cane is being burned for harvest. The fire doesn’t kill the plants but it cleans up the paddock so that there is not so much residue on the stalks of cane for the harvester to remove before it is transported to the sugar mill for crushing. I’ve only started burning this year after realising I was losing an unacceptable amount of cane in the cleaning process as opposed to burning the cane pre harvest. I was cutting green (as opposed to burning) in a bid to retain organic matter and build soil carbon on my property. We still retain a lot of the residue by slowing down the extractor system on the harvester and burning early morning or late afternoon rather than in the heat of the day. Over the last 20 years we have been able to increase our organic carbon levels from two percent to eight percent, which when measured by the NSW DPI is equivalent to the sequestration of 20,000 tons of carbon or 77,000 Co2 equivalents.”

Image 3: Tweed sugarcane grower Robert Quirk with the NSW Premier Gladys Berejiklian and Robert’s local Member of Parliament Geoff Provest who visited his farm to talk about drainage problems and carbon capture by sugar cane.

Robert and the neighbouring farmers all burn together, one week on then three weeks off. Utilising the BoM wind forecast, the team is able to plan the timing of their burning activities. “This site is very accurate,” Robert said.

Climate change

Robert is a third-generation farmer who has been on the land since 1959 when he left school. “I’m dyslexic and schools didn’t cater for that. I couldn’t wait to get out of there, I’d go to school to eat my lunch, then I was gone as quickly as I could!” He educated himself after leaving school and is now a guest editor for two international climate change publications. He has also been an invited speaker in 35 countries on the topics of sustainable farming, remediation of acid sulphate soil, mechanisation of the sugar cane industry and dealing with a changing climate. Robert was also an MCV program Climate Champion for several years and therefore has a long history of working with researchers to improve growers’ ability to management climate variability risks. “The climate is changing faster than farmers can adjust so it is important that we share how each and every one of us is dealing with it,” Robert states.

Image 4: Two of the thousand or so visitor to visit Robert’s farm over the last 20 years: a PR China student and his professor from University of Queensland

During his time, he has seen a lot of changes both to farming practices and the seasons.

“We changed from tillage to minimal till. We still cultivate for planting every six to eight years.”

“The biggest changes I’ve seen is longer dryer periods and then these bloody intense rainfall events and the variability of rain between areas quite close together. For example the Gold Coast can get 25mm and here we get 2mm, we are only 20km apart.”

Robert’s farm is also only half a metre above sea level which not only causes problems in rainfall events due to lack of drainage but also creates more work.

“We have to pump water off our farm and into the river every day during rainfall events,” Robert said, a job that many Australian farmers would find a very foreign concept. With two pumps working, he moves around four megalitres per hour off his farm.

Rising sea levels

Robert has also noticed the sea level rising and its effect on his farming operation.

“I’ve noticed changes in the way the moon cycle came closer to the earth early this year which helped to explain the very high low tides we had in March, the prediction is that this phenomenon will return around 2030 when once again we will experience tides of plus 50 centimetres above the predicted tides. We are experiencing more extreme tides which means at these times, our sugarcane has little natural drainage so we have to pump most of the water.” Drainage is critical to sugar cane. Up to five days there is very little damage, after that there is a production loss of 7 tonnes per hectare per day. “For every centimetre rise in the sea level we have to pump an extra ten Olympic size swimming pools off the farm,” Robert said

Image 5: One of the pumps Robert uses to pump water off his farm. This one is electric and starts as soon as the rain starts. The second is driven by a tractor when needed. At the time the picture was taken the river was about 1 – 5 metres higher than Robert’s farm.

Robert is hoping these events are not the new norm “but we are thinking they are”. If the sea level was to rise to 30cm, Robert would find it difficult to farm his land: “It would be very, very challenging. In saying that the Netherlands have been farming below sea level for centuries, so nothing is impossible.”

Robert manages the water in a number of ways: “We use levees, pumps, mound planting and minimum tillage as well as larger drainage channels to take advantage of the lower tides when they occur. In a perfect world to keep this very productive land in production we will need government funded infrastructure to help drain these flood plains.  These flood plains are very productive producing three times the global average for rain-feed sugar cane.”

Using the weather and climate forecasts

For Robert, knowing what rain is coming from June through until the following March is critical for his farming operation. By keeping a close eye on several key climate drivers and using a mix of weather forecasts he can better prepare for the growing season as well as the day-to-day activities on farm.

This year with the current negative Indian Ocean Dipole event underway and the constant threat of water drowning his farm each day, Robert is “worried”. “We really don’t want any more rain at the moment. More and more farmers in the Tweed area are now planting at or above the natural ground level. This is done by making mounds and planting into them, each 1.8m inter row then becomes a drainage channel. While it only gives us elevation of 20cm, the mounds become oxygenated very quickly after an event allowing for microbes to do their work. Some are also trying to run another ratoon rather than replant,” (ratoons are a new shoot that grows from the base of the existing cane plant after harvest (up to 6 – 10 ratoons)).

“The MJO is another one of the predictions we watch closely, so each week when Roger Stone releases his opinion on the climate for northern Australia, we read it with interest: when the MJO will next be in our region. Most if not all our major rainfalls this year has been when the MJO is in our region. The one in late August to early September was the first dry visit this year, let’s hope this continues!”

Robert has been involved in providing feedback to researcher partners involved in the nationwide project, ForeWarned is ForeArmed (FWFA), funded by the Australian Government Department of Agriculture, Water and the Environment’s Rural R&D for Profit program with co-investment from 14 project partners. “The project aims to deliver state-of-the-art forecasts beyond the traditional seven-day weather forecast so that farmers can make more informed decisions when it comes to extreme weather and climate events,” Robert said. “They are valuable products. Being forewarned we can change things around in our system according to what these products are forecasting.

However, when the BoM releases its climate outlooks predicting the chances of above or below average rainfall, Robert would like more detail, specifically when and how much. “In the old scale there was a year when Tweed had 26 inches of rain and it was a good year, rain came regularly. Then there was a dry year when we had 140 inches. The rain came in the first few months of the year, then nothing.”

For planning day-to-day activities on farm Robert and other growers in the area use the Norwegian site YR, MetEye which Robert believes “is very accurate” as well as the BoM’s radar, especially in storm season. “We also watch the high-pressure systems and the weaken polar vortex to estimate if we will get frosts.”

Robert keeps one other climate forecast up his sleeve: “This is not very scientific but if the foxes and hares are building in the bottom of our drains and scrub turkeys are building on the flats and in gullies, we feel mother nature is telling them it is OK.”

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