Mulch trials for soil health

July 21, 2020

Mulch trials on Tablelands farms are adding another layer to soil health-boosting practices.

Commercial lime grower Michelle Milicevic hopes trials of tea tree, woodchip and hay mulches will help to reduce chemical inputs and inform other primary producers.

The Milicevics are one of two lime producers involved in trials by natural resource management organisation Terrain NRM and Wet Tropics Soil, a group of more than 60 Far North farmers working to improve soil health on their properties.

“This year we’ve been working on lessening chemical inputs and applying compost and mulch is part of this,’’ Mrs Milicevic said. “We usually spray to keep the weeds down so that our sprinklers work well. Now we’re mowing the weeds and throwing them back under the trees instead, and the trials are giving us an idea of how different types of mulches will perform.”

Terrain NRM’s Rowan Shee said two sites with tea tree, woodchip and hay mulch would be monitored on a six-monthly basis for the next four years.

“We’ll compare baseline soil assessments with a focus on carbon levels and building up the soil’s biology,’’ he said. “We’ll also be looking at things like water infiltration and compaction levels.

The trials are part of Terrain NRM’s Digging Deeper Plus soil health project that has worked with more than 150 farmers from all over the Wet Tropics region through on-farm workshops with soil health practitioners, tailored farm management plans and free soil tests.

The Wet Tropics Soil Group’s Mal Everett said the benefits of mulch were well-documented – from building up organic matter and improving water-holding capacity to suppressing weeds and reducing run-off.

“Now we want to look more closely at the soil biology side of things,’’ he said. “Hay has always been the standard mulch for commercial crops. With a gradual resurgence in the tea tree industry and sources for more woodchip on the Tablelands now seems like a good time to be assessing options.”

The Digging Deeper Plus project is supported by Terrain NRM through funding from the Australian Government’s National Landcare Program.

Mr Shee said annual soil assessments were also happening on seven Tablelands cattle properties where farmers were changing to rotational grazing practices to improve soil health and productivity.

“We are looking at how effective grazing changes are in building carbon in the soils, increasing the root depth of grasses and improving general soil health,’’ he said.

Find out more about your soils with this series of Wet Tropics videos featuring agriculture ecologist David Hardwick.