2014 Australian Macadamia Society 40th Anniversary Industry Conference

1. Integrated Orchard Management
Prepared by: Tim Salmon
Teaming With Microbes
16/10/2014

2. 2014 AMS 40th Anniversary Industry Conference proudly presented by
Teaming With Microbes

3. 2014 AMS 40th Anniversary Industry Conference proudly presented by
Teaming With Microbes
OR
Why we apply mulch instead of profiling and
prune instead of mechanically hedging.

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Outline
1. Why “Teaming With Microbes”?
2. Farm history
3. Strategy
4. Results

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Why “Teaming With Microbes”?
Soils Part 3: Good soil is teaming with life
One teaspoon of good soil contains;
 One billion bacteria
 Several metres of fungal hyphae
 Several thousand protozoa
 A few dozen nematodes

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The role of soil microbes
 Decompose organic matter and release nutrients/produce humus
 Release nutrients from soil mineral particles
 Fix atmospheric nitrogen
 “Feed” nutrients and water to plants
 “Tie up” nutrients preventing some from leaching
 Produce plant growth stimulants (vitamins, hormones, enzymes)
 Protect roots from invading disease pathogens and nematodes
 Improve soil structure
 Detox – remove wastes produced in farming process

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Why not team with soil microbes?
Without a healthy biologically active soil our farming systems are
increasingly dependent on us to provide the right inputs at the right time in
the right quantities to maintain production. More;
• Monitoring
• Intervention
• Energy
• Money
• Waste (pollution)
• Insight & understanding

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Requirements...not too hard
 Enough food (something containing carbon)
 Adequate moisture
 Air (not compacted => top soil)
 Liveable temperature (not too exposed)
 Freedom from harmful soil conditions (salts, extreme pH,
pesticides...)

9. 2014 AMS 40th Anniversary Industry Conference proudly presented by
Requirements...not too hard
 Enough food (something containing carbon)
 Adequate moisture
 Air (not compacted => top soil)
 Liveable temperature (not too exposed)
 Freedom from harmful soil conditions (salts, extreme pH,
pesticides...)
 Many of our practices are either actively or passively counter-productive
with regard to soil health

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Farm history to 2011
 Soil replacement trial following millennium drought about 2004 – too costly
 Trial using round bailed hay 2006
 Purchased profiler December 2007 – persistent dry conditions
 By 2010 obvious(?) production declining
 Phytophthora
 Reduced canopy density – reduced hedging requirement
 Increasing fertilizer requirements
 By 2011 lost root volume approximately 60m3/ha – shallow soils
 Penetrometer tests...

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Production history 1991 – 2013
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Strategy development
 Exposed roots revisited
 Importance of light reaching the orchard floor
 Importance of canopy architecture
 To profile or to mulch?

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Exposed roots revisited
 Exposed roots = lost root volume = loss of buffering
 moisture
 nutrients
 Best soil lost or moved further away from tree
 Tree’s energy requirements increased(?)
 Biological activity of remaining soil is lower
 Nutrient cycling compromised – more fertilizer
 Disease likely hood increased

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Importance of light reaching the orchard floor
GROUND COVERS:
 Importance of plants in supporting the soil foodweb
 Diversity, diversity, diversity....(more resilient system,
mycorrhizae)
 Incorporate carbon in soil (mulch/compost surface only)
 Water infiltration, reduced runoff of nutrients
 Aeration (combat compaction)

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Importance of canopy architecture?
 Tree height is important –
 Crop protection
 Shade orchard floor
 Tree’s energy requirements(?)
 Canopy architecture contributes to root exposure(?)

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To profile or to mulch?
 Cultivation strips carbon (soil biology)
 Cultivation damages soil structure particularly if moisture not
optimum (compound risk) – managing soil moisture is costly
 How much material is available to profile - potential to expose
sub soil (recovery of ground covers, temperature, run-off, root
volume)
 Slope
 Damage to macadamia roots

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Our strategy:
1. Make soil health a priority - better manage future costs
2. Direct cut grass, leaf and displaced mulch to cover roots
3. Mulch over exposed roots - offers reduced risk, many benefits
to soil health and lower cost(?) when compared to profiling
4. Postpone hedging - selectively prune where shading is
extensive

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What we did:
 Since 2011 prior to 2014 crop (last mechanical hedging 2009) –
prune to raise irrigation lines whole farm, selective limb removal
trial, tree removal trial, coppice trial & chipped everything
 2011 purchased zero turn mower and stopped using herbicides
 2012 purchased mulch spreader & prior to 2014 crop applied
25m3/ha of mulch, now 40m3/ha, 60m3/ha looks optimistic =
(100L/tree, 160L/tree, 240L/tree)

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After application of 25+m3/ha mulch 2012 & 2013
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Is our strategy successful?
 Other variables
 Crop nutrition – frequency increased, total ==
 Irrigation - significantly improved DU
 Context
 Previous crop(s) – bounce?
 Season – most severe?
 Too soon to tell; a one-off or first of trend?

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Is our strategy successful?
 Other indicators
 Canopy density improved
 Phytophthora reduced
 Penetrometer improvements
 Soil Foodweb analysis
 The value of baseline measurements
 Some way to go but encouraging
 Nitrogen supply: “Low nutrient cycling and availability. Need
more protozoa and beneficial nematodes to cycle nutrients”

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Afterword
 Don’t have to replace lost soil in one go to get some benefit – response to
mulch may be slower than soil(?)
 Covering exposed roots will provide immense benefit but may be short lived
if consideration not given to causes – need to do more to “tie down” mulch
 Sufficient light to support the growth of some ground covers is essential for
longevity and resilience
 Three low cost ways to check your objectivity -
 Soil health card
 Soil foodweb analysis
 Benchmarking

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Recommendations & Acknowledgements
 Soil foodweb analysis – www.soilfoodweb.com.au
 “Teaming with Microbes” Lowenfels & Lewis 2010