DAMS are up front and central on most farmers’ minds right now and Agriculture Victoria was actively on-topic in its extension role this week at three locations.

Breakfast sessions at Nangeela, Nareen and Karabeal on Tuesday, Wednesday and Thursday respectively were involved with conveying knowledge to farmers which is likely to be critical to the provision of water for livestock in the district during the coming summer and early autumn.

The seminars were led by Agriculture Victoria’s (AgVic’s) Ararat-based land management extension officer (LMEO), Clem Sturmfels and Benalla based LMEO, Greg Bekker with support from Hamilton’s AgVic’s meat and wool south-west regional manager, Kate McCue and Chris Blore.

Attended by about 55 district farmers, the sessions were focussed on the management of catchment dams most of which are now at worryingly low levels for this time of year in spite of improved rainfall since July.

The problem, Clem said, was lack of run-off due to unsaturated soils which may now be growing grass but are not ready to fill dams.

Dams have been emptying due to higher stocking rates as well as the loss of water from evaporation which is exacerbated by wind.

Over summer, he said, a large dam could lose 30 per cent of its water to evaporation, while this figure rises to as much as 50 per cent for a smaller one.

Dam water measurement is the key

A KEY message of the seminar was the importance of knowing what water was being held on a farm as summer approached.

Clem made the point that while all farmers would know how much cash they held in their bank accounts, very few could say how many megalitres of water was held in their farm dams.

Together with Greg Bekker, they demonstrated how reliable estimates of both dam capacity and current water in store could be made by farmers without resorting to any expensive equipment.

The techniques involve measuring the dam by striding out its dimensions (one long stride for a person without groin problems is about one metre).

The second stage was to measure the depth of the dam and the final stage was to calculate the volume by applying the dimensions to the Summer Water Calculator (which can be found at Agriculture Victoria’s website below)

Depending on whether you measured the total dam capacity or the amount of water currently in the dam, your capacity or water inventory for that location will be provided.

The programme cleverly makes adjustments for the slope of dam sides.

Greg was inspired about eight years ago to invent an exquisitely simple and cheap tool for measuring the depth of dam water which is appropriately named DAMDEEP; it is composed of a fishing float, fishing line, three beads and a lead sinker. (its construction and operation are eloquently explained in a video – see link below).

Water quality

WITH reference to water quality, they both spoke in some detail about the importance of monitoring – touching on the risks associated with salinity and how in certain cases it can be reduced by mixing it with fresh water.

Greg also cautioned that saline water can cause clay to flocculate (form clumps) which can result in a leaky dam – just what you don’t need.

Another potential problem is bacterial infection in a dry season which can cause severe and potentially life-threatening scouring.

Blue-green algae was a problem with low dams and Clem recommended water testing.

Sediment control in run-off situations (once strong rains return) is often necessary, with further recommendations including netting barriers as being effective since they gradually build up a permeable barrier of twigs and plant debris.

Straw bales can prove too abrupt a barrier with water washing over them while silt sheeting; it is often used by municipalites, but clogs up too quickly and tends to be flattened.

Carting water?

A FINAL subject of carting stock water to the farm was discussed – with the course providers saying that for cattle it was definitely not feasible and for sheep it was a logistical nightmare if, indeed, it was even feasible.

To cart stock water in a drought, one needs a high-volume standpipe to fill the road-tanker, a large capacity tank to receive the water and a contractor available who was able to deliver water daily.

Essentially, a too-hard-basket scenario.

This was a thoroughly practical and timely series of seminars which should help farmers through the coming summer.

The Agriculture Victoria material to calculate ‘How much water does my farm need?’  can be found at bit.ly/3YlrBiz

A video explaining the DAMDEEP tool can be found at youtube.com/watch?v=Kp21tB5hPj8