Agricultural application of biochar – Western Australian research stimulus and barriers
Prior to 2010 very limited research was applied to the agricultural use of biochar in Western Australia. WA cereal growing regions are impacted by dryland salinity and landholders were encouraged to incorporate an oil mallee agriforestry system as a salinity amelioration strategy. The Oil Mallee Company of Australia endeavoured to develop an integrated processing operation, producing energy, activated carbon and eucalyptus oils. This led to the early biochar research in the mid-west. Dr Paul Blackwell, then a research scientist with the Department of Agriculture WA, led the trials, incorporating arbuscular mycorrhiza (from Western Minerals Fertilisers) in the treatments.
Warren Catchments Council’s 10,000km2 footprint falls in the high to medium rainfall zones, now subject to significant drying conditions. Soils are varied though the intensive agriculture area’s deep gravelly loams do not share the same constraints as the shallow acidic sandy soils of the early trial sites, roughly 600km north east. The presence of clay (cation exchange enabler) and higher organic matter levels were assumed to alleviate the need for a biochar amendment in the south west.
Investigations into the multiple benefits of biochar at Warren Catchments Council (WCC) coincided with the political will to sequester carbon. WCC facilitated sawmillers’ and farmers’ interests in exploring avenues to enter the Carbon Market by arranging guest speakers – initially Barry Batchelor (Black Earth) and Dr Syd Shea (Rainbow Bee Eater Project), and to alert them, through workshops, to biochar’s agronomic potential.
Doug Pow was an early adopter of biochar, applying his concept of using biological tools to sequester carbon – cattle and dung beetles. WCC secured a low budget grant from the WA State NRM Office to replicate what was proving to be a very successful strategy. Applications for funding through Action on the Ground or Filling the Research Gap for further research were unsuccessful, and, with a change in government, that funding opportunity ceased.
Biochar – cattle and dung beetles
A chance meeting between Doug Pow and Prof Stephen Joseph at a biological farming forum in 2015 sparked the latter’s interest in quantifying the effects of dung beetle buried biochar-infused manure. The assembled research team drew together findings from other studies to help explain the visible effects – healthy cattle and improved pasture performance - as well as data confirming nutrient cycling through laboratory analysis and the use of X-ray photoelectron spectroscopy.
Mat Daubney agreed to replicate the trial on his 1,000 head Bannister Downs Dairy to see if the dung beetle-biochar action could assist in renovating perennial pastures without the conventional practice of taking them out of rotation during establishment. This was an ideal green-field site since there was minimal dung beetle activity. The trial was too short-term to build up the dung beetle population to have a measurable impact on soil nutrient analysis. However, the immediate reduction in dairy odour was appreciated by staff! Bannister Downs Dairy won Dairy Australia’s 2017 cream award – motivation to develop a more comprehensive research project, based on Archim Gerlach’s study, to determine biochar’s effects on animal health, growth rate, fertility, milk properties, feed conversion efficiency and emissions reduction.
Feeding biochar to beef cattle is gaining momentum with several producers known to be implementing the practice and interest is obviously widespread as WCC regularly receives queries from further afield.
Biochar-amended rhizosphere in avocados
The success of biochar’s effect on pasture improvement inspired Doug Pow to consider biochar’s structural properties and how they could be utilised to re-engineer the soil in an avocado orchard so it more closely resembles its native andosol soil. Another low budget grant was awarded through National Landcare Programme funding to test whether increased porosity would alleviate locally prevalent waterlogging conditions to mitigate Phytophthora cinamommi infestation. As avocados are largely surface feeding, it was speculated increased aeration and infiltration would enhance growing conditions.
The trial comprised a row of 36 treatment trees matched with a control row 36 divided into three blocks of 12 according to their soil type: karri loam on clay, gravelly loam on deeper clay, sandy loam on gravel. Each block had four trees of 5%, 10% and 20% v/v biochar incorporated into the top 300mm (to determine influence of application rate). All trees were mulched with a poultry manure/sawdust/woodchip mulch but two trees from each treatment had biochar included in the mulch mix (to determine influence on plant performance). There were insufficient replicates – in treatments and samples - in this trial for statistical reliability however visible differences in early growth impressed local producers sufficiently for there to be rapidly increasing uptake of the practice, coinciding with the dramatic expansion of the local avocado industry.
Measurements taken in September 2016 recorded the treatment row mean out-performed the control row in tree height (18%), trunk girth (21%) and diameter (21%). However, the effect was greatest in the karri loam on clay: height (20%), trunk girth (26%) and diameter (27%).
Soil testing didn’t indicate any significant difference in nutrient availability suggesting greater efficiency in nutrient use (or acquisition) in biochar amended soil to generate such superior biomass production. Tissue sampling (composite samples of treatment and control rows) conducted in July 2015 recoded 8% less Cl in the treatment row. Irrigation water at the time had a reading of 486μS. However the Cl reduction in most recent tissue testing (July 2017) was insignificant.
Final tests and detailed analysis of soil, tissue and microbial biomass data, and physical measurements are to be conducted in this trial that ends in December 2017. Producers who have maintained regular observations have multiple reasons for adopting the practice: salinity mitigation, accelerated early growth to foster resilience, Phytophthora cinammomi control tool, increased interest in biological inputs. Most have opted to use the 5% application rate as there is little observable difference between treatment rates.
This trial has generated many more questions than answers! Much more research is needed to explain biochar’s role in this trial and whether similar results will be achieved in different tree crops, soil and climatic conditions.
Biochar Network of Western Australia Inc
Recently incorporated, the Biochar Network of WA seeks to provide a mutually beneficial forum to build the capacity of users and producers of biochar. WA is a large state and a website, in development, will assist in knowledge sharing. BNWA will lobby for a WA biochar industry and seek to secure resources for research and development.
Gerlach A, Schmidt HP: The use of biochar in cattle farming, the Biochar Journal 2014, Arbaz, Switzerland. ISSN 2297-1114 www.biochar-journal.org/en/ct/9 Version of 01 th August 2014 Accessed: 03.08.2017