Adding cover crops to rotation improves cotton yield

Infiltration rates of red brown earth soil improved by cover crops


Cropping
NSW DPI Cotton Researcher, Hayden Petty said their trial found planting a cover crop in between cotton improves yield.

NSW DPI Cotton Researcher, Hayden Petty said their trial found planting a cover crop in between cotton improves yield.

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Trial helps Southern NSW growers adapt soil to cotton

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A NSW DPI trial has indicated in red brown earth soils found in Southern NSW, planting a cover crop between cotton can improve yield.

A barrier to growing cotton in Southern NSW has been the soil type.

DPI cotton researcher, Hayden Petty explained red brown earth soils have more issues surrounding infiltration and water-holding capacity compared to grey self-mulching clay soils which cotton production is more suited to.

He said the study looked at how infiltration on red brown earth could be improved by different rotation strategies.

The first was a long fallow coming out of a winter crop, mimicking what most growers are doing currently.

"Cereals are harvested in December, when it's too late to plant cotton, so fields are long fallowed through the following summer and winter season," Mr Petty said.

The second was a cover crop followed by sorghum as it could be planted later than cotton and provide more cover during the summer season.

While, the third, having the most impact on infiltration rates, was back to back cotton with a cover crop sprayed out early between each season.

The control was back to back cotton with a fallow instead of a cover crop.

Mr Petty said they also tested the affect of three different species of cover crop, barley, radish and a vetch and oats mix.

But they found there was little difference in yield increase between the species.

The last 12 months of the trial will look at how spray out times for cover crops affect cotton yield. Photo supplied.

The last 12 months of the trial will look at how spray out times for cover crops affect cotton yield. Photo supplied.

"It was more the rotation that had the effect, having the cover instead of bare ground seemed to increase the yield on this soil type," Mr Petty said.

He said despite the findings there were some practical limitations to growing back to back cotton with cover crops in between.

"Water and time are the big ones, growers need to prepare their ground before planting cotton, so there are implications of having cover crops," Mr Petty said.

He said with 12 months left of the study they would now look at the affect of different spray out times for cover crops.

"We've gone a shot gun approach and sown every plot down to have mixture of the barley, oats, radish and vetch," Mr Petty said.

"The variable this year will be the spray out times, what's the impact of the cover-load."

"How much biomass will change what's actually happening under the ground to have an influence on the pores and water available to the plant."

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