WA trials help de-risking efforts

That's the word from Greg Rebetzke, chief research scientist at CSIRO Agriculture and Food, after he travelled to three Western Australian trial sites last week.

"This project is a national effort co-ordinated to improve understanding and knowledge of agronomic factors important to de-risk deep sowing,' Dr Rebetzke said.

"This is the second year of the national project that incorporates nine research partners and is led by CSIRO, with strong support from the grains industry, including the Grains Research and Development Corporation (GRDC).

"We've got eight sites throughout WA this year that are looking at sowing depth and also the impact of soil amelioration and non-wetting soils, and the capacity for deep sowing to help improve timely emergence when things don't go well in terms of soil types.

"We're looking at some new coleoptile genetics that will permit growers to plant deeper into moisture and the early indications on non-wetting and ameliorated soils are very positive."

Dr Rebetzke said the trial sites he visited most recently were at Corrigin, Muntadgin and Dowerin.

"It rained much later than what we would have liked in those areas, which meant a delay in germination and emergence for shallow sown crops," he said.

"GRDC has been investing in this work looking at these three experiments which represent just a small portion of the wider set of about 20-plus experiments across the country.

"We are looking at what are the necessary agronomic tools needed to support deep sowing if needed, fertiliser requirement, placement and amounts and types of fertiliser, the impact of seed size and press wheel pressure when sowing and also looking at seed dressing such as fungicides and the importance of pre-emergent herbicides, soil temperature and soil moisture.

"It's a huge project - it's about de-risking deep sowing and, with the breeding lines that are coming through the breeding programs, we aim to educate growers so they have the tools and the confidence to reliably sow deep to ensure a crop."

Changing rainfall patterns were a big driver for undertaking this research.

"We hope to mitigate the risk of dry sowing if moisture is available deep and can we use that moisture," Dr Rebetzke said.

"What are the important bits of knowledge growers need to ensure reliable germination and then reliable emergence with deep sowing?

"We're not saying you should deep sow every year, but when you have years when you've had that summer rainfall and you've protected that moisture, it's sitting there, there may be an opportunity of sowing deeper rather than risk dry sowing and ensuring emergence."

Dr Rebetzke said throughout the trials the sowing depth was determined by the coleoptile length.

"The depth is limited by coleoptile lengths," he said.

"Part of the project with current varieties and future varieties is to identify what are the range of coleoptile lengths and how seed size, temperature and soil type will impact the expression of that coleoptile length.

"It depends on the soil type and temperature, but we are looking at up to 10 to 12 centimetre sowing depth, reliably it is 8-10cm, so much deeper than current recommendations are.

"With current varieties we are limited to about 4-5cm."

Once the trials were completed Dr Rebetzke hopes the outcomes will be beneficial to the wider grains industry.

"Yes, we are only looking at wheat," he said.

"But the technology and the findings are being translated into other crops, for example GRDC has an investment in canola and a small investment in oats, so as the technology has been demonstrated to be a value in wheat, GRDC is planning to invest in translating it to other crops."

The trial sites in Queensland, South Australia and New South Wales are next on Dr Rebetzke's itinerary.

"We have multiple trial sites in NSW where there are more heavy textured soils where soil temperature and soil strength are resistant to coleoptile pushing, which is also an issue in South Australia and Victoria.

"Then I will head back to WA and focus on experiments further north in the State at Mingenew and Yuna."