After months of late nights, painstaking maths, and trial and error, Condamine, Queensland grain grower Jake Hamilton is using the summer months to “shift dirt” after specially designing contour banks to improve water management on his 5600-hectare family farm.
For Jake, the contour banks are part of a broader plan to improve water management across the farm. “While it remains dry, we are continuing a program of repairing gully erosion on our steeper country and building contour banks to prevent future damage. At the moment, water can run across the surface, like a scar across the land. It takes the topsoil with it,” he says.
Jake farms with wife Felicity, his father Scott and his wife Janne. Although the farm, on Queensland’s western Darling Downs, is not in the reef catchment and therefore not subject to catchment regulations, it is something the family is still keen to control. “We don’t want to lose that soil and see it run into waterways. Levelling solves waterlogging issues by controlling water flow across the soil surface and allows us to begin to repair uneven soil fertility.”
The work is unique because Jake is building contour banks that follow a graduated design. Essentially that means the banks get larger in size as the length and water volume increases.
“This achieves a 60 per cent efficiency gain because we are reducing the amount of dirt that needs to be shifted. It follows a formula we developed and was made possible by the land-forming design software from Stuart Pocknee and his team at T3RRA.”
The summer earthworks also include levelling another 300ha of melon holes on brigalow country. Melon holes are naturally occurring depressions, up to four metres deep on the Hamilton property, surrounded by associated mounds. “Like a series of little hills,” he says.
Levelling is an expensive exercise, at about $500 a hectare, so the plan is to do a few hundred hectares every year. The benefits make the cost worthwhile. “In an average-to-wet rainfall season, moisture profiles are refilled and waterlogging is eliminated, while management practices such as spraying efficiency and harvester performance are also improved.”
Jake says levelling the farm is something the family business has wanted to do for some time. “We are always trying to follow best management practice and wanted to level melon holes and address run-off for some time, but it was too expensive.”
Technology changes and a collaborative approach have helped see it through. With neighbours, the Hamiltons jointly purchased an aerial, high-accuracy LiDAR (light detection and ranging) elevation survey to assist with planning.
The remote-sensing method is used for measuring exact distances and Jake says it was critical for the design. “Spending a bit more on a higher-quality survey leads to greater savings down the track and getting a heap of neighbours together helped us all be able to afford it.”