Testimonials

Outstanding results from split decision

A Burdekin cane farm has achieved some significant yield increases, thanks to a switch to split nitrogen applications using EASY N® fertiliser.

Justin Luckel, Farm Agronomist for 1,400 hectares of irrigated farmland owned by SISL Group, started trialling split nitrogen applications on the worst performing of their six farms near Giru in 2009.

Results from the first year showed yield increases of 5-12% compared with the area where all of the crop’s nitrogen supply was applied straight after harvest.

Yields in this standard treatment area averaged just under 104 t/ha. In the trial area, 70% of crop nitrogen needs were applied after harvest using granulated fertiliser and the balance was applied as EASY N around 14 weeks later. Similar results were repeated the following year using a liquid dunder blend.

Phosphorus, potassium and sulphur applications were balanced so that the same rates of nutrients were applied across each area.

Due to the success of the split nitrogen trial, the treatment was extended to the whole 270 hectares of that farm in 2010.

In addition, split nitrogen trials were established on three more of their farms in 2010.

“This first farm just wasn’t performing as it should, so I thought splitting nitrogen was worth a try,” Justin said.

“In cotton and other irrigated broadacre crops, it is standard practice to split nitrogen applications to improve nitrogen use efficiency, and I thought it might work in cane too.”

Justin said the soil on the farm was light with a low cation exchange capacity, indicating nitrogen was more likely to be leached than in heavier soils. EASY N was chosen for its ease of application.

“We use a high clearance spray rig with droppers, aiming a stream of EASY N at the base of the cane,” he said.

“It is applied just on the edge of the hill, so we minimise contact with the leaves and keep it up out of the water.

“Once the irrigation goes past, it pulls the nitrogen into the soil for use by the crop.”

Justin added that water testing of tail water where EASY N had been applied showed no significant increases in nitrogen levels.

EASY N is stored in an on-farm tank which holds a B-double load of fertiliser. He said the change to split nitrogen applications has turned the Giru farm around.

“We’ve got some of our best plant cane there this year,” he said.

For cane growers considering the potential for split nitrogen applications on their farm, Justin recommended leaving an area aside and testing it for themselves.

“The results will probably depend on the soil’s ability to hold on to a full year’s nitrogen supply,” he said.

“My advice to anyone running on-farm trials is to always be there when the trial is being cut,” he said.

“It’s too easy for the results to be lost in harvest if you’re not in the paddock at the time.”

Soils under scrutiny

Justin uses soil testing extensively to fine tune crop nitrogen requirements on the 1,400 hectares of irrigated cane land.

“The soil types on the six farms range from heavy Barratta clays and good structured cracking clays, though to sodic duplex and alluvial soils,” he said.

“We’re building up our average yields and expect to harvest 155,000 tonnes this year, but it’s not an overnight achievement. It’s a result we have been working on over the past five years.”

He said last year was particularly challenging with most of the crop harvested from the backup track machine and around 30% of the cane left in the paddock, due to the wet conditions.

“My role covers everything to do with growing the crop, including water, herbicides, fertiliser and soil management,” he said.

“We are in an area where soil testing is a requirement under the Reef Regulations. Last year I conducted 16 soil tests, while under the regulations, we only needed to do five,” Justin said.

He also uses yield maps, EM maps and elevation data from a GPS to provide information on his cane paddocks.

Yield mapping, for example, picks up high and low yielding points in the paddock, so Justin can target them for soil testing, which may reveal the reasons behind the variation in the results.

This approach has been used successfully in the past to reveal clear cut issues such as low phosphorus and zinc levels in specific areas of the paddock. In some cases, it has been sodicity issues, addressed through variable rate gypsum applications.
“You can’t just change your fertiliser strategy based on yield mapping – you’ve got to see what the underlying issue is,” he said.

“It might come down to some hollows in the paddock where the water is sitting, soil issues or it might be a nutrient issue.

“In the Burdekin region, soil types can be quite variable too, which can make a big difference. I’ve seen paddocks with four or five different soil types in 20 hectares, for example.

“We are not quite ready to go to variable rate nutrients yet. I don’t think we have enough information on blocks, but we are working towards it.”

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