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Goomalling Trial Moulds Clay Knowledge

04 January 2012

AUSTRALIA - Claying at a rate of 260 tonnes per hectare and using a rotary spader to incorporate the clay is a cost effective and profitable way of ameliorating non-wetting sands on a farm near Goomalling, according to preliminary trial results.

Details of the three-year study conducted on Trevor and Renae Syme’s property are outlined in the latest edition of the Grains Research and Development Corporation (GRDC) magazine Ground Cover.

The on-farm trial, which started in 2010, aims to investigate the most profitable rates and incorporation methods for clay, and is supported by WA’s Wheatbelt Natural Resource Management under the Australian Government’s Caring for our Country initiative.

It is testing different clay rates (nil, 260t/ha and 520t/ha) combined with a variety of different incorporation systems: rotary spader, rotary hoe and offset discs.

In a separate paddock in 2010, the Syme family also tested nil incorporation with spading and mouldboard ploughing.

By June 2010 there was a noticeable difference in crop germination between the clayed and non-clayed treatments after receiving 15 millimetres of rain.

The area treated with 260t/ha of clay and spading, seeded at 70 kilograms per hectare, went on to yield 1.41t/ha of noodle wheat, while the nil plot yielded 0.66t/ha.

Although Mr Syme estimated the cost of spreading and incorporating clay to be about $880/ha, he said the exercise never had to be repeated and the returns began to add up after two years, depending on grain prices and crop yield.

Mr Syme first attempted claying in 2001, when he decided he could no longer afford to allow the patches of non-wetting sand within his paddocks to spread.

He said wheat planted on untreated, non-wetting sand yielded from 1.0 to 1.5t/ha in an average season, well below the 3.5t/ha potential of other soils.

Another challenge of non-wetting sands was that weeds tended to germinate all year round, making effective control difficult when they were at different stages of maturity.

“You gain a lot of production through claying and you don’t lose any land,” Mr Syme said.

TheCropSite News Desk

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