31 August, 2009
Around 100 growers and consultants attended a series of dryland cotton information meetings in southeast Queensland hosted by Cotton Seed Distributors and Monsanto.
CSD’s Darling Downs based extension and development agronomist John Marshall said the main purpose of the meeting was to highlight the new technologies that are available to dryland growers – tools that reduce the risk and uncertainty that has been traditionally associated with the crop.
“With sorghum prices down this year, a lot of growers are looking for other dryland summer alternatives and some of these people are dismissing cotton because of memories they had of the crop in the 1990s,” he said.
“Since that time we’ve seen the introduction of Bollgard II, Roundup Ready Flex and Liberty Link technologies which simplify insect and weed control practices in cotton and allow better management of costs,” he said.
“Because of these technologies, many people now consider dryland cotton to be as easy to manage as sorghum. Using data from the past two seasons, those growers using these technologies averaged two ground rig sprays for sucking pests, one over-the-top herbicide, a shielded sprayer as a lay-by application, and occasionally an inter-row cultivation and chipping – mostly for fleabane,” he said.
In the past, one of the major downsides of dryland cotton was the risk of major cost blow-outs due to insect control problems, but according to John Marshall, the Bollgard II product has all but eliminated this.
“Bollgard II offers season-long control of heliothis, our major insect pest. It works whether it’s wet or dry so we don’t get those situations where you need to get the plane in to treat skip-row crops – that was where costs got out of control,” he said.
“When you compare the growing costs of cotton and sorghum, cotton is about 40 percent more but almost half of these costs are incurred around the time of harvest – in fact up to this point sorghum and cotton’s input costs are almost identical,” Mr Marshall said.
According to John Marshall, a cotton rotation into fields that have grown predominantly summer and winter cereals will be invaluable in improving soil structure and utilising nitrogen deep in the profile.
“We see many instances of a ‘nitrogen bulge’ at about a metre depth in soils that have grown a lot of sorghum and wheat because its leached down the profile and out of reach of these crops,” he said.
“Cotton, with its tap root, can forage up to two metres into the profile, turning this nitrogen into dollars,” he said.
“We’ve also seen plenty of instances in recent years where the good dry-down that cotton provides does an excellent job of breaking up the compaction layers from headers in no-till situations,” Mr Marshall said.
Despite these new technologies, Goondiwindi-based CSD extension and development agronomist David Kelly said there are still some ‘golden rules’ that people need to follow if they’re contemplating dryland cotton.
“You need the right soil type – soils that allow good exploration by roots and are able to hold plenty of moisture – a plant available water-holding capacity of somewhere around 150mm in the milder areas and maybe a bit more as you head further west and north would be a good starting point,” he said.
“Ideally, cotton should only be planted into a full moisture profile – anything less than this will increase the risk significantly,” he said.
“Using stubble cover greatly improves water infiltration in fallow and in-crop, and minimises the sand-blasting we often get during those hot, windy November days,” he said.
“Cotton’s vigorous root systems mean it is ideally suited for skip row situations – there is a lot of research that allows growers to weigh up the yield, cost management and fibre quality interactions between the different row configurations,” he said.
“You need to establish a good, even stand – not doing so will put you on the wrong foot straight up,” he said.
“Finally, growers should employ an experienced agronomist to regularly check their crop. While the Bollgard II and Roundup Ready Flex technologies take away a lot of the complications, it’s still a high value crop and a good person keeping an eye on it is a great investment,” he said.
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