Fallow crops reduce soil run-off in Ingham floods

Fallow crops have reduced soil run-off in the Ingham region in the wake of recent flooding rain.

As crops re-emerged from paddocks that were lakes, Herbert Cane Productivity Services Limited Manager and cane grower Lawrence Di Bella said farmers from around the district were reporting significantly less soil erosion in areas with ground cover on fallow fields.

Lawrence and Hayden Di Bella are trialling mixed fallow crops thanks to Project Catalyst - a partnership between innovative Queensland cane growers, The Coca Cola Foundation, WWF, Bayer CropScience, the Australian Government, Terrain NRM, Reef Catchments, Catchment Solutions, NQ Dry Tropics, Wilmar and Farmacist.

Their small plot trials include separate and mixed plots of 25 species from soy beans, cow peas and pigeon peas to sunn hemp, sunflowers, canola, lablab, tillage radishes, tropical mustard, stylos and desmanthus.

The trials began in late 2016 and are producing promising results.

“We can see the positive effects of a mixed crop – in shading out weed species, in providing organic nutrients that go back into the soil and in reducing the rate of inorganic fertilisers,’’ Lawrence said.

“We know fallow crops help with soil nutrients and weed pressure and we know monocultures create unhealthy soil conditions by building up soil pathogens.

“What we are exploring in this trial is whether greater diversity in the fallow period reduces the need for inorganic nutrient application, reduces fertiliser costs, helps with inorganic nutrient losses and creates a healthier soil profile.”

Soil tests have revealed mixed plots have a low ratio of bad and a high ratio of good nematodes. Higher nitrogen, potassium and phosphorous counts have also been recorded when crops are mixed, bringing different benefits from each species and in some cases balancing out less favourable traits out.

Herbert Cane Productivity Services Limited’s Megan Zahmel, who is working with the Di Bella family on the Project Catalyst trial, said the sunflower-sunn hemp plot was a good example of this.

“Sunflowers have a lot of good points – they pull up zinc and phosphorous that is down deep in the soil and they have produced good worm counts compared to other fallow crops,’’ she said.

“But we’ve also seen that our sunflowers have increased root knot nematodes. When mixed with sunn hemp we see a decrease in bad nematodes and additional positive results like an increase in nitrogen and biomass levels.”

Terrain NRM’s Project Catalyst Coordinator Michael Waring said fallow crops would always face more challenges than cane in periods of flooding.

“What we are learning from soil experts is that we need diversity in our fallows to gain the most from them,’’ he said.

“Most Wet Tropics cane farmers who are planting fallow crops are growing legumes like cow peas or lablab, a type of running bean.

“In the Herbert River catchment during usual rain events, growers have had success with cow peas on raised beds, reducing root rot from waterlogged soils.

“The challenge is finding beneficial plants that will grow together and survive the rigors of the Wet Tropics. To date we have found that some mixed fallow crops have minimised the risk of crop failure because different species are dominant at different times and when climatic conditions change, like dry or wet periods.

“It’s about trying new things, something a lot of farmers are continuing to do to improve soil health and, by doing so, improve water quality leaving their farms.”

Lawrence said mixed fallow cropping now had a place in his family’s farming practices.
“We implemented controlled traffic 14 years ago and we have seen numerous benefits,’’ he said.

“Hayden and I want to continue to improve soil health and carbon levels on farm. We believe that mixed fallow cropping is the next step and is a relatively simple way of achieving some of our goals.”

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