An ingenious strategy for paddock adaptation to high-rainfall zone (HRZ) cropping has seen Derrinallum growers Matt and Rachel Hinkley overcome waterlogging as the main constraint to grains productivity and profitability in their farm business.
The couple's strategy, integrating raised beds, drains and controlled-traffic farming (CTF) practices, has also achieved a year-on-year lift in average crop yields across the 1750-hectare property in the western districts of Victoria.
For instance, the Hinkleys' long-term average wheat yields have lifted about two tonnes per hectare in the past eight years since they implemented the strategy on most of the farm's cropping area.
Testament to these gains was the 2019-20 season, in which the Hinkleys' cereals averaged 8t/ha - even though they faced their fourth-wettest winter on record and received 460 millimetres of growing season rainfall.
In the past, before they implemented the strateg - particularly its framework of raised beds and drains - such high rainfall caused waterlogging that wiped out 70 to 100 per cent of their crops.
Underpinning these gains - reduced waterlogging losses and increased crop yields - are more resilient, robust soils that promote optimal crop performance.
The beneficial effects of soil amelioration as part of the on-farm earthworks range from improved soil structure and aeration to better moisture infiltration and increased microbial activity, Matt says.
The strategy, custom-built on a paddock-by-paddock basis, consists of flat-top raised beds, which are 150 to 200mm-high, with centres spaced two metres apart.
The raised beds are linked to a network of head, intermediate and tail-drains that control water movement over the soil surface.
Also helping to conserve and promote improved soil quality is the Hinkleys' transition to a 12-metre, 3:1 CTF system, geared to restrict heavy machinery to permanent wheel tracks.
Matt estimates that expenditure on the ongoing work to develop raised beds and drainage, using their own machinery, is about $200/ha.
To date, they have invested more than $1 million in these works on about 1200ha in the past 17 years. Of this outlay, the couple has recouped their capital investment in each stage of the works within two years, Matt says.
This year, they built the raised bed-drainage system on another 270ha of cropping country during dry conditions in February and March to help minimise soil compaction from heavy machinery.
The Hinkleys use a laser bucket with GPS guidance, followed by a grading machine, 12m grader board and bed-former for the earthworks, the paddock design for which is guided by topographical mapping.
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More information: Matt Hinkley, 0428 531 731,firstname.lastname@example.org