Mallee yield boost with seed treatment

The project, based at Loxton and led by Nurtrien Ag Solutions Berri agronomist Shane Phillips, focused on how a newly created seed treatment made from Seasol, zinc, manganese, molybdenum and bacterial isolates and metaboliates, performed in low-rainfall cropping areas.

It was applied at five litres a tonne to chickpeas, lentils and peas in plots at Loxton and surrounds, as well as at Kapunda.

Mr Phillips said highly variable pulse crop performance in the region prompted the trial because poor inoculant performance had caused plant growth issues, including disease resistance and size.

"The northern Mallee of SA is associated with alkaline soils and generally low rainfall in most seasons and it impacts some crop growth," he said.

Mr Phillips said growers in the region were in search of a better-performing break crop to help boost soil nitrogen levels.

"Growers increased canola planting but it was high risk and it meant growers needed more information about pulse crops and how to make it work better in their system," he said.

"This also meant inoculant benefits increased in significance."

A NEW project to help enhance cereal production in low-rainfall environments was launched last year by a Riverland agronomist, after a previous seed coating trial to help boost rhizobia inoculant performance showed "great results".

Nurtrien Ag Solutions Berri agronomist Shane Phillips said the new project will run until 2023.

"A three-year pulse trial at Loxton has formed another long-term project targeted at specific weather conditions," he said. "We are researching the role that bacteria can play in enhancing cereal production in low-rainfall districts.

"We are looking at seed coating, down the seed tube and foliar applications with bacteria to lower frost risks in crops.

"Research in other areas suggests that boosting colonisation, growth, of bacteria could play a very important role in the rhizosphere and also impacting on plant leaf surface areas."

The pulse trial at Loxton had plots of chickpeas, lentils and peas that were coated with 3 per cent bacterial isolates and metaboliates, 2.4pc zinc, 2.2pc manganese, 0.08pc molybdenum and 30pc Seasol, while control plots were coated with rhizobia strain only.

The coating cost, including inoculant, was about $23 a tonne and Mr Phillips said inspection of crops throughout the three growing seasons showed significantly different visual plant growth vegetative responses between the seed coated and conventionally sown crops.

"Lentils' plant colour was also increased in the coated seeds and there was a reduction in rhizoctonia infections, suggesting a possibly biological suppression as a result of increased colonisation," he said.

"It had significant benefits in plant performance and there was a very clear visual reduction of root disease."

At harvest, there were significant yield increases, while the inspection of root nodules also showed increased nodulation because of the seed treatment and greater colour intensity, suggesting an increased nitrogen fixation.

Lentils yielded 677 kilograms a hectare, while the control was 614/ha. Field peas went 911kg/ha with a 729kg/ha control, but chickpeas did not increase yield significantly, going 640kg/ha compared with a 602kg/ha control.

"Seed coats consistently enhanced inoculant performance and caused significant increases in soil nitrogen reserve," Mr Phillips said.

Soil samples also identified that sowing coated seed increased post-harvest soil nitrogen.

Post-harvest deep nitrogen tests revealed increased soil nitrogen from 41kg/ha to 61kg/ha in lentil crops at Loxton and 16kg/ha to 88kg/ha with faba beans grown at Kapunda.

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