24 July 2012

3 minute read

Oceania

A producer demonstration site (PDS) set up on Larrawa station near Fitzroy Crossing has shown waterponding can improve land condition, water and soil nutrient retention, and potentially boost returns from increased forage production.

At the PDS, waterponding was used to hold water where it fell to reduce soil erosion and silt build-up in the nearby Christmas Creek.

The open ponds allowed this water to soak into the soil and become available as soil moisture to promote vegetation growth.

“Within one year the waterponding area changed from being classed as severely degraded and eroded to a significantly improved poor land condition (D),” said Department of Agriculture and Food WA Development Officer Matthew Fletcher, who ran the trial.

“It now has capacity to improve to C condition in the next few years.”

Making comparisons

The PDS was a joint effort between the Brockhurst family, MLA, Rangelands NRM WA, Central West Catchment Management Authority (CMA) NSW and the Department of Agriculture and Food WA (DAFWA).

Matthew said open water ponds at the site were the most successful at slowing water movement, allowing time for it to soak into the soil and facilitating establishment of perennial and annual groundcover.

He said through the PDS, local pastoralists had seen the importance of using a level to ensure ponds were well designed, getting bank height and width right to increase longevity and the potential for this method to be used on a range of soil types.

The cost to rehabilitate one hectare at Larrawa with two water ponds – each 210 metres long – was about $150 in ripping and construction with a 16G grader and seeding hybrid sorghum. This equated to 32 cents per metre of dirt moved.

Other techniques

Water spreader banks constructed with a grader along contour lines also showed potential, especially for spreading concentrated water flow on sloping country.

But these were more expensive to construct than ponds, at about $1.49/metre.

Matthew said an opposed disc and crocodile plough used to build pits and ridges at the Larrawa site were less successful than other rehabilitation techniques trialled because they were unable to increase groundcover.

Key findings from the Larrawa PDS to improve soil health:

• Mechanical regeneration, including water ponds, ridges and banks, can work and a combination of methods has proven most successful;
• Professional surveyor advice is a good idea for pond establishment;
• Ponds can be constructed quickly with a grader along contour lines;
• The right bank height and width will increase longevity and at Larrawa banks were up to 200m long, 65cm high and 2m wide at the base;
• Water spreader banks are best used in transition areas where vegetation stops and scalds begin to slow overland water flow;
• At Larrawa these were constructed with a grader and had bank heights of 65cm, a base 2m wide and a break every 100m.

TheCattleSite News Desk