Soil & Land

Sowing strategies could boost crop yields on sandy soils

Research is demonstrating the potential for sowing strategies to significantly improve crop productivity on sandy soils in the southern cropping region.

Sandy soils, a dominant feature of the southern region especially in low rainfall zones, are often subject to low productivity due to conditions such as water repellence, low water-holding capacity and low fertility affecting crop emergency and early vigour.

However, research partly funded by the Grains Research and Development Corporation (GRDC) is showing that the choice and operation of seeding system technology can have a positive impact on crop productivity.

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Dr Therese McBeath from the CSIRO in Adelaide (South Australia) and Dr Jack Desbiolles from the University of SA have been involved in a collaborative research effort that has produced insights for grain growers in areas of low rainfall and sandy soils.

Speaking at GRDC Grains Research Updates in the southern region, Dr McBeath and Dr Desbiolles said research at various trial sites in SA and Victoria had shown that sowing strategies can influence soil moisture, nutrition and disease, and ultimately grain yield potential.

“For example, field trials suggest crop performance in sandy soils improves under paired row seeding systems,” Dr Desbiolles said.

“Preference should be given to systems with higher seedbed utilisation using paired row or spreader boot designs to reduce the risk of fertiliser toxicity, secure seed placement onto undisturbed soil moisture, and effectively maximise crop establishment and yield potential.”

Dr Desbiolles said sowing into non-wetting sands could significantly benefit from furrow seeding technology that effectively clears the top water-repellent layer away from the seed row and promotes seed placement into moisture. Pilot trials using a proof-of-concept scooping share design ahead of a triple disc achieved 90 percent wheat establishment, up from 64 pc without it.

“Furrow sowing can also benefit from wide ‘V’ press wheel profiles to create stable furrows, and also maximise water harvesting potential.”

GRDC-funded work in Western Australia has shown that moisture in non-wetting sands tends to be greater directly under the previous year’s rows where stubble is kept standing. Sowing on or near the previous year’s standing rows also significantly improved crop establishment and biomass in non-wetting sands during the southern trials, however, this did not translate to grain yield benefits following the dry springs of 2014 and 2015.

Dr Desbiolles said the use of in-furrow banding of fungicides in liquid fertilisers consistently boosted control of Rhizoctonia root rot disease and crop response relative to seed treatments alone during the course of a research program supervised by Dr Alan McKay (South Australian Research and Development Institute) over the past five years.

Rhizoctonia is one of the major biological constraints to cereal crops on sandy soils in the Mallee region and on SA’s Eyre Peninsula, especially where non-wetting soils are an issue. The combination of seed fungicide treatment and in-furrow banding produced the highest levels of protection.

Dr McBeath said further work was needed to validate whole-of-paddock approaches integrating the abovementioned early recommendations and to demonstrate best-practice solutions.

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