YEALERING farmer Chris Walton is currently sowing his 44th crop and planting a far bigger program than if had he not grown saltbush on his property to arrest encroaching salinity.
About 180 hectares of the Walton's property was affected by salinity, land which Mr Walton said was cropped until the late 1980s.
"You would notice while harvesting, rings with a salt crust in the lower lying areas of the paddocks," he said.
"We did $100,000 worth of drainage work in the 1970s and 80s - that was when we found out that grey clay was impervious to underground water movement.
"Eventually we could see the fingers of salt starting to reach out from the creek lines."
Mr Walton, who farms with his wife Dianne and son Michael and his wife Natalie, also block-planted more than 100,000 trees, including flat topped yate, Kondinin blackbutt and oil mallees, along the property's creek lines.
"They looked really good but they didn't stop salt from coming back in other areas," he said.
In the 1980s the family began sowing 'shotgun mixes' of saltbush, clover and lucerne and had a good response - except on the grey clay soils.
Encouraged by the performance of the saltbush, the Waltons joined a research collaboration, including the Department of Agriculture and Food (DAFWA), to explore the benefits of alley farming saltbush with annual pastures in 2003.
The partners in the 10-year study also included the CSIRO, Australian Wool Innovation, Land and Water Australia and the Future Farm Industries Co-operative Research Centre.
The project aimed to explore the natural resource management impact and determine whether the once useless land could generate some productive pastures.
A 25ha plot affected by salinity was sown with saltbush alleys with improved annual pasture in between to compare the production, soil salinity, surface run-off and salt exported with an adjacent 25ha untreated control site over a 10-year period.
The treated plot was planted with 660 stems of river saltbush and old man saltbush seedlings in 10-metre alleys, with a mix of balansa, Persian, gland and sub-clovers with barrel and burr medics in between.
"We wanted an understorey because barley grass does not fill sheep," Mr Walton said.
"Sheep also cannot live on saltbush alone and they need something else as well or you'd end up carting hay."
Meanwhile, the control plot, which was comprised of mostly barley grass, was left untreated.
Between 2003 and 2012 the surface run-off and soil salinity was monitored in each plot.
"Within the first few years I started noticing the salt run-off had reduced drastically," Mr Walton said.
Over time, DAFWA and the CSIRO's data confirmed that there had been a significant reduction in salt run-off - with just one tenth of the salt discharged from the improved site in comparison to the control.
Over the last three years of the trial the treated site had 40 per cent of the comparable run-off to the control site and dramatically less nitrogen (20pc), phosphorus (40pc) and sediment (20pc) was washed off.
DAFWA research officer Don Bennett said the results showed that the saltbush significantly reduced the damage caused by salt build up on the surface.
"The results show that saltbush systems can dramatically reduce the salts, nutrients and sediment discharged in surface run-off, sequentially over time," Mr Bennett said.
"The reduction in shallow soil salinity was caused by the saltbush system drying the near-surface profile and lowering the water table during the important late summer to mid-winter periods, in particular, when annual pastures are germinating and establishing."
The project also found the lower water table, as a result of the saltbush system, was seasonal.
"Although the water table reduction was not of a large magnitude, just 0.5 metres, it occurred mostly in the late summer to mid-winter period, preventing salt build-up in surface soils and this, in turn, reduced salt, sediment and nutrient runoff to streams," Mr Bennett said.
"The water table drop also resulted in much lower soil salinity levels within the pasture's root zone.
"Soil salinity levels fell to between one third and one tenth their original levels, depending on their initial severity.
"This response provided a better environment for annual pasture growth during the critical germination and establishment phases."
The results from the Walton's plantings suggests that the saltbush-based systems are a valuable short and medium term strategy to boost productivity, stabilise saline areas and reduce salt, nutrient and sediment run-off into streams.
Mr Walton said not only did the saltbush system generate natural resource benefits, it also renewed the productivity of the land that had been lost to salinity.
The control site has now also been planted to the saltbush alley farming system, using old man saltbush and tall wheat grass, sub-clovers and medics, to provide more feed for sheep, while another 50ha of saltbush has been sown around the farm.
One or two ewe flocks are generally run on the site after shearing in autumn and sheep are sometimes used in winter for controlled grazing.
"We put the sheep on it for about six weeks and afterwards you can hardly tell that they have been there," Mr Walton said.
CSIRO trials on the property also found that saltbush was also a valuable feed for sheep.
Research scientist Hayley Norman said the annual pasture understorey was the key to the improved sheep productivity.
Dr Norman said the saltbush was particularly valuable during poor seasons, when it improved the performance of the annuals by drying the topsoil and to stem salt leaching from the soil surface.
"In autumn 2006, which was an average season, the saltbush and understorey contained 61 per cent more edible dry matter and provided 2.8 times more grazing days per hectare compared with the control," she said.
"This resulted in an additional 3.18 kilograms of clean wool growth per hectare when compared with sheep run on the unimproved salt land.
"In autumn 2007, which was a drought year, the difference between the improved and unimproved areas was even greater with 4.6 more grazing days provided by the saltbush and sown understorey."
Mr Walton said the saltbush system had also had a positive benefit to the local ecosystem.
"It's been great to see the impact on biodiversity and the birds come back," he said.
"I've seen birds and insects buzzing around that weren't there before."
The results of the trial have now been published and incorporated into DAFWA's ongoing natural resource management strategies.
Broader modelling has also been conducted to predict what could happen if the saltbush system was expanded on a catchment scale.
DAFWA principal research officer Richard George said modelling suggested that in addition to the on-farm benefits of the saltbush system to address salinity, it could also protect and enhance natural resources off-farm.
"By keeping the subsoils drier and water tables a little deeper, we slow the rate of salt water run-off and reduce topsoil salinity, which in turn improves run-off quality and the impact downstream," Dr George said.
"If what we have done at a field scale can be successfully expanded on a larger scale, management of saline and degraded land adjacent to waterways could reduce salt concentrations and nutrient run-off, especially at times when flows are low and water quality considerations are paramount.
"The benefits from this would include reduced salt loads and/or concentration to downstream water bodies, with a positive impact on stock water and biodiversity, a diminished risk of algal blooms and limiting sedimentation of river pools."
Mr Walton said the saltbush system was worth the investment and, according to his own analysis, the one-off establishment cost of $200-300 a hectare was easily recouped.
"The initial cost is expensive but it's there for a lifetime," he said.
"I just bit the bullet, fenced off the area and did it properly. Once it's done, it's done.
"You treat it like a crop and use a double knock down and treat every pest you can think of.
"If you only do a bit every year it does not take long. It's worth the effort and the area becomes a wonderful feed resource.
"We're pretty happy with our operation now."
p To learn more about the Walton family's experience growing saltbush visit agric.wa.gov.au and search for 'salinity introduction'. Article supplied by DAFWA.