Using Raised Beds and Beneficial Fungi to Resture Soil Health
Case study prepared by SoilsForLife an Outcomes Australia initiative.
Upon learning the links between soil health and waterlogging, Brian and Sandra Wilson concentrated on improving their soils, adopting a technique to improve drainage and biologically managing stubble.
By creating raised narrow beds of soil Brian and Sandra Wilson achieved major improvements in drainage and the structure of their soil. This led to more reliable crop yields and the production of considerable amounts of stubble.
A stubble digestion program was initiated to manage cereal stubbles, using brewed cellulose-digesting bacteria and fungi combined with grazing. The wheat stubble is now incorporated into the soil and is used to renovate the beds.
A biological blend, a mixture of brewed microbes, humates, basalt, soft rock phosphate and various trace elements, was spread to rectify soil deficiencies.
As a result of the various techniques applied, the changes to the soil both physically and chemically are remarkable, transforming from hard setting grey clay to a red/brown non-sticky loam.
The ratio of calcium to magnesium moved towards a desirable 5:1, improving the availability of phosphorus, potassium, sulphur and other nutrients. This compared to conventional practices of applying up to eight tonnes per hectare of lime, and correcting pH to around 6, which had not improved calcium levels.
Breaking Down the Stubble
While the narrow raised beds were effective in managing waterlogging, with increased productivity the Wilsons found they had to deal with higher stubble loads of up to 10 tonnes a hectare. Stubble burning was a commonly accepted practice in the district, however the Wilsons felt that this was not sustainable in the long term.
Attempts to mulch the stubble and sow directly into them was defeated not by physical restraints, but by chemical limitations. Excess stubble was resulting in allelopathy – exudates from wet straw were poisoning the following crop. In 2001 Brian met Adrian Lawrie at the Wimmera field days. His small biological products company LawrieCo was promoting cellulose-digesting fungi to break down straw.
In 2002 Brian purchased enough product to treat 17 hectares. This was not overly successful, possibly due to poor brewing technique. In 2003, he installed a tank and brewing pump to properly multiply the fungi and applied it to another 17 hectare plot. This time a better result was achieved, so the Wilsons expanded the area treated. The results were successful.
“In 2005 we treated the barley stubble in Weir South on one side of the creek only. Sheep had access to both sides, but only grazed the treated side. Brian removed them in score 3 condition when it was felt that the paddock was bare enough; around 1000kg a hectare dry matter. The untreated side had only been ‘picked at’”, notes Sandra.
“The results of the biological program trialled over small areas were so encouraging that the management of the whole farm is now using that system.”
Brewed cellulose fungi and grazing has now become standard practice to manage cereal stubbles on Briandra.
The high biomass produced by pea and barley stubbles tends to clump together with wind, but these are now reduced by grazing. The biological stubble digestion program makes them more digestible to stock, and they become a valuable food source. As the health of the soils improved, Brian and Sandra found the need to incorporate the wheat stubble, which is not eaten as effectively as barley, into the soil to get it to breakdown quickly enough. To overcome the biomass problems the Wilsons invested in specialist machinery to incorporate the wheat stubbles at a shallow level, and then reform the beds.
Adjusting Soil Chemistry, Biology and Structure
“While we were successfully growing high yielding crops, with high inputs of fertiliser, it seemed that pathogens were an increasing problem. Lucerne flea attacking wheat crops at the 2 to 3 leaf stage became more common, and barley yellow dwarf virus (BYDV) also prevalent. LawrieCo suggested trying the nutri-blend product [now called ‘biologic blend’]. This dramatically changed the chemical analysis of our soils.”
Previous soil tests on Briandra had shown high levels of iron and magnesium, resulting in tie up of nutrients and poor soil structure. After adding the biologic blend, the Wilsons found that the phosphate available for plant uptake, measured through Olson P levels, had increased dramatically.
“Pasture paddocks where Olson P had stabilised in the 12-15 range despite annual dressings of 20+ P increased to 19 with the addition of only 10 P in the form of soft rock phosphate, together with 5kg a hectare of boron humates”, Brian explains.
Calcium levels had also increased. This improved the calcium to magnesium ratios, moving it towards a desirable 5:1, from a previous 1.5:1, thus improving the availability of phosphorus, potassium, sulphur and other nutrients. This compared to previous conventional practices of applying up to eight tonnes per hectare of lime, and correcting pH to around 6, which had not improved calcium levels.
Soil structure, already improved by minimising waterlogging, changed from light grey clay, to a reddish brown loam. It was less sticky and had increased infiltration rates.
Brian notes, “The results of the biological soil improvement program trialled over small areas initially, then across the whole farm have been very rewarding. Without the improvements we have made in improving the soil health and fertility over the long term, our soils would continue to be waterlogged, anaerobic, hard setting, sodic and acidic soils”.
The Wilsons are proud to note, “We have shared the lessons we have learnt at Briandra. Over many years of serving on local and regional bodies we have been able to influence the focus of several groups on soil health. In 2012 soil has been listed in the top six assets of the regional catchment strategy”.
Raising crop beds (1996)
Using brewed fungi combined with grazing to manage cereal stubbles
Spreading biological blend on soils (2002)
Increased area available to crop through improved drainage
Adoption of practices across community
Imprved soil health and fertility
Increased sheep weight gain