An innovative, Australian presentation offers inspiration for South African farmers. It demonstrates how using a motor grader for water ponding can rehabilitate soil and increase its moisture content.
What is water ponding?
Traditionally, water ponding just refers to the accumulation of rainwater or seepage on a flat surface. Where drainage is poor, this is obviously undesirable.
In Australia’s dry conditions – not dissimilar to those in South Africa – water ponding has been adapted to farmers’ advantage. Rather than modifying surfaces to encourage run-off, farmers construct vast ponds to help capture and retain water.
Allowing rainwater to pool and stand on hard-crusted surfaces causes the soil to soften and swell.
This process naturally breaks up scalded surfaces and hard crusts. Water can then infiltrate the soil beneath.
The end result is better soil quality with improved water retention.
By helping rehabilitate drought-stricken land, water ponding can provide farmers with more productive, arable land.
Water ponding using graders: example from Australia
Role players in land rehabilitation and farming in Western Australia established that high-powered motor graders are the most effective construction equipment for water ponding.
They have put together a practical video presentation of the dos and don’ts of building water ponds.
The video provides precise information on construction techniques, and the recommended pond and pond bank dimensions. It also covers adjusting and operating a grader for the best results.
Key points in the video include the following recommendations:
- Water pond size and scope: 210 metre bank length, holding 10 cm of water, over 0.4 hectares.
- Cutting edges: ¾ cutting edges with the blade tilted at a right angle, approximately 10 to 12 cm forward of the base. The blade must be in line with the outer side of the wheel.
- Wheel lean: into the bank.
- How to put blocks at the end of the bank: lift the grader blade at the end of the survey mark.
- Ripping the soil: rip along the survey marks, and through the centre of the pond, to allow for the maximised blending of the surface and graded soils.
- 1st, 2nd and 3rd passes: to construct a bank with a 2-metre base width and 60 cm height.
- Water pond maintenance post construction: the importance of seeding and good stock control.
Surveying tips
Proper surveying of the land is crucial to the water-pond construction process. It is conducted from the top of the clay bed, down.
Surveying can be effective using hand-held or vehicle-based laser equipment. Ponds are only constructed on the survey lines.
Water pond configuration
Water ponds are typically U-shaped, cover 0.4 hectares and have single crest banks of approximately 210 to 220 metres in length. The optimal slope is 0.1 to 0.3% or 10 to 30 centimetres in 100 metres.
Motor grading tips for water ponding
With efficiency and economy in mind, a heavy-duty 16 motor grader is the equipment of choice. It’s used to construct shallow pond banks and rip the hard surfaces on either side.
The construction process is opposite to that of surveying. Grading starts at the bottom of the clay bed and works up the slope.
Along with the grader operator’s experience, the positioning of the blade determines the success of the project. A ¾-cutting edge and right-angled tilt is best. For more detailed grader operator instructions, take a look at the video.
To avoid excessive pooling and the potential breakage of banks, it’s important not to grade beyond the survey marks.
Banks should be constructed with full blades of soil to create “puffy”, gently-sloped embankments with rounded sides.
What KH Plant offers
At KH Plant, we rebuild Caterpillar motor graders to exacting standards. This makes it possible for our customers to buy graders that look, perform and last like new, at a fraction of the cost of new machines.
We don’t offer the 16 graders used in the Australian water ponding presentation, but trusted workhorses like the Caterpillar 140G are suitable for water ponding (as well as a host of other tasks on South African farms).
Contact us for more information about the motor graders we offer or to discuss your needs.
