Mill mud and phosphorus forums gather in Tully

Mill mud and phosphorus were hot topics at forums for cane growers in Tully recently.

Organised by the Wet Tropics Sugar Industry Partnership, the events brought soil scientists Dr Phil Moody and Dr Peter Larsen to the region to talk about crop nutrition and trial results.

WTSIP’s Tully district extension officer Alex Lindsay said growers had been asking for more information about mill mud and phosphorus application.


“This was an update on issues related to mill mud distribution, regulation and its value for crop nutrition, and on key aspects of phosphorus in sugarcane crop nutrition, as well as selection of phosphorus fertiliser forms and rates,’’ he said.

“Phosphorus behaves differently in soils to nitrogen and it’s even more important than with nitrogen that soil is sampled correctly. The way phosphorus is absorbed differs significantly between soil types, even from one metre to the next, so to get the best results growers should sample before any cultivation occurs, follow the SRA Guideline values for determining fertiliser rates and consider using precision agriculture for blocks with variable soil types.

phosphorus forum

“If the phosphorus levels are too low, the crop won’t be able to use the nitrogen fertiliser as efficiently as it otherwise could. If phosphorus levels are too high, it can interfere with the uptake of zinc and other micronutrients, which again could limit growth as well as potentially causing environmental problems by stimulating blue-green algae growth in waterways. There’s a fine line between avoiding overuse and making sure the crop is getting optimum levels of phosphorus.”

He said Wet Tropics growers had been trialling innovative practices with mill mud and the forum was a chance to share knowledge. WTSIP trainee extension officer Simon Cristaudo presented data on the nutrient content of mill mud produced in Tully, showing there can be great variation in the rate of application per metre.

Dr Peter Larsen spoke about Wilmar Sugar Australia’s trials and recommended growers introduce mill mud banding practices to localise benefits to the stool, increase productivity and reduce costs and the risks of run-off to the Great Barrier Reef.

“Mill mud and mill ash are important soil ameliorants that contain nutrients, so we also need to consider how it fits in with a grower's overall nutrient plan. We recommend using the Six Easy Steps to work out how much to reduce fertiliser by, and this will vary from block to block,’’ he said.

phosphorus forum

The two events brought more than 80 farmers, extension officers and agribusiness representatives to Tully. Growers also had the chance to quiz an expert panel including representatives from the Department of Agriculture and Fisheries, Incitec Pivot, Metagen, Sugar Research Australia, Total Grower Services, and Tully Cane Productivity Services. The mill mud seminar was chaired by Tully Sugar Productivity Services Manager Greg Shannon.

These events were funded by the Queensland Government’s Reef Water Quality Program and the Australian Government’s Reef Trust III program, and delivered by WTSIP thanks to funding from the Great Barrier Reef Foundation.

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