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Less Fertiliser Does Not Mean Lower Sugar Yield

Less Fertiliser Does Not Mean Lower Sugar Yield

27 March 2015

AUSTRALIA - Early trial results show a new approach to fertiliser application in Wet Tropics cane farms is ultimately boosting the quality of water heading downstream, with minimal effect on cane tonnage or sugar content.

Department of Agriculture and Fisheries (DAF) scientists are heading into the second season of a three-year trial, which aims to demonstrate to farmers that the Industry Best Management Practice of "Six Easy Steps", or 6ES, is effective for calculating nitrogen application rates.

DAF Senior Agronomist Derek Sparkes said nitrogen was an important fertiliser in cane production, however its run-off was a concern for the health of the Great Barrier Reef.

"Industry best practice under the 6ES method recommends a lower amount of nitrogen than has been traditionally applied," he said.

"In these trials we are using standard and new commercial forms of nitrogen to test if reduced rates still produce the same yield, both in tonnage of cane and sugar content."

Initial trial results:

  • 6ES application rates of 130kgN/ha show no significant difference in cane yield or sugar content than rates of 160kgN/ha.
  • N rate trials after legume fallows showed zero N did result in reduced cane yield and sugar content, but 50kgN/ha produced no significant difference to 100kgN/ha.
  • Two Agrocote Controlled Release (CR) trials were established in Silkwood and Freshwater comparing a 50:50 blend of CR plus urea with straight urea N. Three rates of N were applied (80 kgN/ha, 120 kgN/ha and 160 kgN/ha). There was no difference (in both cane yield and sugar content) between either rates or products with reasonable yields of 80 – 95TC/ha.
  • Mr Sparkes said ratoon trials have had the same nitrogen treatments as applied in 2014.

"These trials will be monitored and harvested again later in 2015," he said. "To keep pace with new products, two Entec (urea with a nitrification inhibitor) trials have been established to monitor its effect on cane production.

"Treatments will be re-applied for a third time in 2015 to ensure we are getting a true picture of the response to the different products and rates."

The nitrogen trials are funded under the Reef Water Quality program administered by the Department of Environmental and Heritage Protection. This program is part of the Queensland Government's commitment to the Reef Water Quality Protection Plan 2013 (Reef Plan), which aims to improve water quality on the Great Barrier Reef.

Under Reef Plan, DAF is working closely with producers, industry bodies and natural resource management groups to facilitate the adoption of improved management practices that will improve farm productivity and profitability as well as the quality of farm runoff.

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