Improving the value & sustainability of Esperance port zone grain growers.

Peter Luberda - Coomalbidgup

Non wet web
Long term DAFWA trial site on non-wetting deep sands

Area: 1,100 ha
Annualrainfall: 550 mm
Soil types: non wetting sand and sand over gravel
Livestock: 1200 merino-cross ewes
Cropping: canola/wheat/barley/serradella
History: In 2000, 40ha of clay was spread, and a further 260ha was clayed in 2004. Clay on the property is too deep for delving. A further 240 ha on the property was clayed in 2012.

Peter Luberda farms with his father, John on fragile sandplain country close to the Esperance coast alongside the West Dalyup River. The property consists of non-wetting deep sands and sand over gravel, which is prone to both waterlogging and erosion. The soils are generally acidic (pH5).

Over the years, the Luberdas have tried various soil soaker products to deal with water repellence. These gave mixed success and so they began to experiment with clay spreading in early 2000, initially focusing on the very difficult soils. This area had been cleared of banksias and was severely water repellent in the top zero to 10cm layer and contained less than one per cent organic carbon. Weed control was an issue as germination could be staggered and germination of crops was not uniform.

However, in 2004, a dramatic incident occurred when a fire triggered from an electricity pole swept through the back of the home block. This resulted in completely denuded paddocks that required immediate attention to ensure that the topsoil was not lost through erosion. The obvious approach was to clay spread the area and a contractor was used.

Since 1999, DAFWA’s David Hall has been running trials on the Luberda’s front paddock, funded by GRDC and WANTFA. These included several clay rates in conjunction with deep ripping. The claying rate for the burnt area was determined from the DAFWA experiments at the front of the Luberda’s property. These experiments had used subsoil material sourced from the property, which contained between 30 to 40 per cent clay. The clay was predominately kaolite. The rates applied were: 0; 50; 100; 200 and 300t of clay-rich subsoil/ha. The treatments were deep ripped at a later date.

The experimental site was managed as a commercial operation. Rainfall was monitored, crop emergence and biomass measurements were collected and soil samples were taken. The profitability of the treatments were assessed using discounted cash flows. The results showed that after eight years, only the treatments receiving more than 100t/ha of clay-rich subsoil, resulting in greater than three percent clay in the topsoil, were more profitable than the control.

Peter therefore chose the highest rate of subsoil material of between 200 to 300t/ha of clay rich subsoil to apply to his damaged back paddocks.The clay was spread with a carry grader, left on the surface, and further spread by smudging. This consisted of up to three passes using a railway girder. The soil was then two-way ploughed to a depth of fit to 10cm. Unfortunately Peter discovered that it is a fine line between leaving the clay-rich subsoil on the surface to be broken down by rain and the surface setting hard in the sun. When the latter occurred, water would either puddle or run-off and after significant rainfall the paddocks would become un-trafficable.

Peter soon realised that better incorporation of the clay was imperative and in 2009/10 he invested in a Farmax spader. This has a power roller on the back that can further break down clods and pack down the topsoil. He chose this machine partly due to the ease of being able to replace worn parts.

The 4m wide spader is towed behind a 250hp Fendt tractor fitted with GPS guidance and autosteer. This helps improve the precision of the spading operation.

In 2010, the damaged paddocks were spaded to a depth of 25 to 45cm to better incorporate the spread clay. Unfortunately, the spading operation brought iron stone rocks from the subsoil material to the surface, which had to be removed to avoid damaging the harvester later in the season. A Mungie rake was used to clear the rocks.

Since spading, Peter’s cropping system has become more productive and flexible. Cereal yields on clayed areas increased from 2.5t/ha up to 4.6t/ha the first year after. The soil has become healthier as a result also – with more fungal activity and earthworms.
Peter suspects that the clay now absorbs nutrients that previously leached through the sandy profile. He has also found that crop rotations are more flexible and because the crops appear healthier they are more able to out-compete disease.
Due to the positive results, Peter invested in his own equipment with the purchase of a second-hand JR carry grader which has a capacity of 15t. This is hauled by a 410hp Caterpillar tractor to reduce some of the compaction on the paddocks.

Peter now also contracts out to other farms in the region with his equipment and will continue further work on his farm also.

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