Water harvesting: lots of good uses and less abuses
GroundCover™ Issue: 33
Along with soil, water is the natural resource that nourishes all agricultural activity. In Australia it's most often a feast or famine situation. And imbalances between vegetation and water flow are fostering the now familiar negative impacts of nutrient loss, erosion, waterlogging and salinity — and of course under-performing crops. Some WA farmers are experimenting with ways to better manage this situation, rather than have it manage them.
At the beginning of the year a deluge had a devastating effect on the Avon River Basin catchment in WA, yet this season there may not be enough rain to see the crops through to harvest.
The deluge was a wake-up call for Colin Stacey on his Quairading property. "We started our water harvesting where there was noticeable erosion, breakaway country and where we were desperately short of water. We contoured the land and channelled the water into dams.
"This reduced the run-off and the transfer of nutrients and topsoil into the waterways and river system. It also reduced waterlogging in the low areas of our property and greatly decreased the amount of water recharge to the watertable," Mr Stacey said.
"I think water harvesting is an imperative part of resource management. Our challenge, or rather our responsibility, as custodians of the land, is to utilise as much of the water where it falls as we can and, if possible, reduce the exit of water from our farms and catchments."
New enterprises and more healthy soils hold water.
In the past, water harvesting was done mainly for stock watering. With the shift to more continuous cropping, Mr Stacey believes there is a lot that can be done with the harvested water and farmers shouldn't rely solely on high-water-usage crops and perennials to lower the watertable.
"Aquaculture is gaining momentum in this region. At Pingelly they are farming rainbow trout and more than 73,000 are being grown this season by 200 farmers. This is an increase of more than 100 per cent on last season. There have also been excellent results from breeding bream and perch in highly saline purpose-built ponds.
"It is possible for bream and perch to thrive in saline water that is 1.5 times more salty than seawater."
Contouring and collection to dams is not the only water-harvesting strategy Mr Stacey has adopted. "We have increased the quality and health of our medic and subclover pastures and this has led to greater water use.
"We have also increased the yield of our crops through better weed management and increasing the soil's organic carbon levels." Organic carbon is the organic matter within the soil which improves the soil structure and helps to develop strong root systems and encourage nutrient uptake. This increases the soil biota, nutrient and water retention at the root zone.
"I believe more farmers should be looking at the organic carbon levels on their properties. The extra moisture that is retained in the soil profile by raising the organic carbon level by 0.1 per cent is extremely beneficial," Mr Stacey said.
Watch out for the neighbours
It is important to have an integrated approach to water harvesting. Each farmer has a responsibility not to disadvantage his/her neighbour, especially those properties that are lower in the catchment.
"The challenge is to use the water and use it wisely and not just retain it on our properties for the sake of it. Water harvesting is all part of resource management and that is our challenge for this century."
Mr Stacey's property is located within the Avon River Basin and he is a member of the Avon Working Group. His strategy is an integral part of the Natural Resource Management Plan which the Avon Working Group currently has available for public comment.
Contact: Mr Colin Stacey 08 9645 1095 web site (Avon Catchment Network): www.avonicm.org.au