Robert Quirk
Region: Tweed River, New South Wales coastal region
Commodities: Sugar cane and cattle
Farming area: 126 hectares of sugar, plus land for a few cows
Rainfall: 1600 mm rainfall per year
Email: rgquirk@bigpond.com
Phone: 02 6677 7227
Other involvement: founding chair of The Better Sugar Cane Initiative, Bonsucro
My colleagues in the Climate Champion program say, ‘Yeah, we really want to know when the rain’s coming.’ I want to know when it’s not coming. Historically the Tweed grows its best crops in the dust. So typically the less rain we get, the more cane we grow.
See what Robert has to say about:
- From dairy to sugar cane
- Climate change - warmer earlier summers
- Drainage, pumps and the threat of sea level rise
- Laser-levelling paddocks to deal with acid sulfate soils
- Building up the mounds
- Trash retention reduces greenhouse gas, good for the soil
- Break crop of soybeans to keep the soil healthy
- Smarter farming reduces inputs
- Using zero till and controlling weeds chemically
From dairy to sugar cane
My grandfather bought the farm in 1905, when it was just open swamp country. It was just half a metre above sea level. The tide used to come into the fields twice a day from a tributary of the Tweed River.
My dad ran 2 dairy farms that weren’t doing too well. The cattle had to be moved every time it flooded. Over the next 30 years, Dad and his brothers dug 10 km of drains with shovels. This reduced the inundation time after floods from 100 days to a week and allowed for the start of our sugar cane farming on the land.
Then my mother decided that my brother and I weren’t the sort of blokes who’d want to keep dairy farming, and convinced Dad to go into sugar cane. When I left school in 1959, we had 40 acres [16 hectares] of cane, and built that up to about 600 acres [243 hectares] before splitting the farm with my brother.
Climate change - warmer earlier summers
We are one of the few areas in the world that will benefit from climate change. We’ll get warmer winters and hotter summers, so we’ll become more tropical. That will be a plus for us because sugar cane needs heat and sunshine to grow.
But there’s a downside. Cyclones will come 500 km further south for every degree the ocean warms, and 2.5°C would put us right in the cyclone impact zone. Science suggests the ocean will probably rise about 1 cm per year. The farm is only 50 cm above sea level now, so we have a problem.
I’ve noticed changes in the climate. Back in 1959, no-one cut ratoon cane before early September [after being cut, sugar cane re-grows from the same stems the following year; this is ‘ratoon cane’]. Now we’re cutting it in June/July, at least six weeks earlier.
No-one ever planted before the first week in September. Now we can start in early August, as long as the weather and the temperature are right. Sugar cane needs a ground temperature of 17°C for the ratoons to shoot, and 19°C for the plant to strike. Those temperatures are coming much earlier.
We’ve got a thermometer in the swimming pool which reflects what the soil temperature is doing pretty well. If the water in the pool is 18°C, we can plant our cane. It’s just a theory but it seems to work for us.
Drainage, pumps and the threat of sea level rise
Sea level rise is the big concern for us. Projections are for about a centimetre a year, and we’re only 50 cm above sea level, so in 50 years we won’t have any drainage at all.
Dad put floodgates in McLeod’s Creek in the 1930s; these were not successful as they kept washing out. Flood mitigation (the Government) straightened the creek in 1964 and fitted modern floodgates. That was the start of the drainage system we have built on ever since.
We pump water out every day. The pumps used to be manually operated, so every morning I’d walk down and see the water had risen through the soil profile, bringing iron and aluminium to the surface and killing the cane.
Now they’re automatic and start as soon as there’s a 10 cm rise in the drainage system, and that’s made a real difference. We pump about 4.5 mL an hour into the river.
But it won’t be enough to save us if sea levels rise. Within 30 years, we won’t have enough freeboard [the distance between the water level and soil surface] to be able to pump all the water out.
Laser-levelling paddocks to deal with acid sulfate soils
All the farming techniques we use to cope with acid sulfate soils also help reduce our greenhouse gas emissions. This was accidental to some degree – we had to beat the soil problem – but now we’re very conscious of what we put on the field, and what goes into the atmosphere.
I’ve seen a photo from 1962 showing the burnt-out acid sulfate soils. We used to have holes through the crop where the cane was killed by the acid and salt coming up from underneath.
There was a big fish kill here in 1987 and everything in the river died. In the past, the community had blamed the sugar industry. They said the mill and farmers were putting pesticides and poisons in the river, even though the mill wasn’t working at the time.
Eventually Clive Easton, an entomologist working for Tweed Shire Council, said, ‘I think this is a result of acid sulfate soils and acid discharge.’ He did some tests and it was, so we had to work out how to deal with the problem. There were 50 tonnes of oxidised sulfuric acid per hectare.
Neutralisation wasn’t an option because there was too much acid, so we sat down with Ian White from CSIRO and Mike Melville from the University of New South Wales to work out how we could contain the acid in the landscape.
The first step was laser-levelling the paddocks. The natural slope was away from the drains, so we had to turn it around. We’ve given the fields a gradient of 0.6%, so everything runs down to the drains and out through the pump. The scalded areas affected by acid and salinity disappeared virtually as soon as we laser-levelled the paddocks.
Laser levelling has been the most expensive remediation work we’ve done, but we saw a return from the year we did it. Now everybody’s laser levelling, everybody’s liming and everybody has a drainage management plan. We are pretty much on top of the problem now.
Building up the mounds
The spaces between the rows are highly compressed by tractor traffic and impervious to water. We plant and cultivate using GPS systems, and tractor traffic has created hard zones between the rows.
We decided to mound the soil and grow the cane above the surface of the ground, between the compacted tracks, to create a micro-environment.
The top of the mound is the only bit we work. The fertiliser goes on there. When the watertable rises, it has to pass through the lime in the mound, and this neutralising medium captures the acid and the nitrous oxide.
Also, when you add nitrogen to anoxic [without oxygen] soils, it volatilises and turns into nitrous oxide, which a nasty greenhouse gas. The soil in our mounds has oxygen in it, so mounding improves our soil and it also reduces our greenhouse emissions.
We don’t lose the nutrients through volatilisation, so we’ve been able to cut the fertiliser way back to about 50% of what we used to use.
The mounds are heavily limed at 10 tonnes of lime per hectare-equivalent, so they’re pretty healthy. The hard zones have a pH of 3.7 [about as acidic as tomato juice], while the mounds have earthworms in them. And earthworms start to survive at around a pH of 6.0 [about as acidic as milk].
Liming was expensive. We’ve got enough calcium in the system to grow 10 crops of sugar cane, but all the carbonate is used up neutralising the acidity. So we’re actually putting the lime on for environmental rather than agronomic benefit.
It took us about 5 years to get the system to work, and it cost a lot of money, but the results have been worth it.
Trash retention reduces greenhouse gas, good for the soil
I don’t burn the cane; instead, I leave the trash on the ground after harvesting. The scientists doing research on the farm helped us work out our processes of trash retention and mounding. It meant a lot of experimenting and some failures, but we eventually got it right.
Brazil cuts 10 times as much cane as Australia and they don’t burn trash at all. If you burn the cane, you retain the potassium and phosphorous, but all the nitrogen’s gone.
The latest research shows that 50% of all the available nitrogen to the crop comes from the breakdown of organic matter, so if you keep organic matter on the ground you can use a lot less fertiliser. Sugar cane has big biomass: 100 to 150 tonnes per hectare.
CSIRO found microbes in my fields that were not present in fields where trash was burnt. So retaining trash is the main thing. We’ve got earthworms – we’ve got all the little goodies that convert organic matter to nitrogen and other available nutrients.
Break crop of soybeans to keep the soil healthy
We do 4 years of cane, one year of beans, and then back to cane, to break the monoculture. We get the same amount of cane off that 4 years as we would growing cane five years straight, we can make money on the beans, and the soil health is also much better.
The beans break the monoculture cycle. They kill some of the nematodes. We don’t need any fertiliser on the plant crop, and they make soil healthy. Before, when the birds followed the ripper or the cultivator, they were eating cane grubs [a native and significant cane pest], but now they’re eating earthworms.
Using zero till and controlling weeds chemically
We used to cultivate every week. So 16 or 17 times in a year, we’d go over the whole farm destroying the organic matter, killing weeds, ripping the roots off and all the things you don’t really want to do. We now do minimum to zero tillage; this allows us to cut in much wetter conditions without damage to the soil or crop.
Now we’ve turned to zero-till and the only cultivation is raking the tops off the stool [the stumps of the cut cane] so we can add the fertiliser and raise the temperature in the mound.
Instead of heavy ripping and busting, we’re spraying. It’s chemical weed control. The energy costs have gone down enormously and so have the tractor hours.
It’s the biggest technological change we’ve made in my 50 years of farming.
Interview date: 1 September 2010
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