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Soil amendment with biochar & compost
Tasmanian Team members: Sally Bound, Marcus Hardie, Alieta Eyles, Garth Oliver, Steve Paterson, Justin Direen, Dugald Close
NZ Team members: Brent Clothier, Steve Green, Markus Deurer, Roberta Gentile
Project details
Aim is to examine the impact of biochar on:
- soil physical & chemical properties,
- soil functioning,
- tree growth,
- tree physiology, &
- fruit quality
Part of the National Apple & Pear Productivity,
Irrigation, Pests and Soils (PIPS) program.
5 year project
Trial description
Location: Mountain River, Tasmania
Cultivar: Fuji (Naga-Fu 2)/M26 (with Royal Gala interstem)
Replicated field trial - RCB with 5 replicates
- 3 trees per plot
Established November 2009 - 1 week after old trees pulled
Replant site (apple orchard) - high fertiliser/irrigation inputs
- no stress
Treatments
1. control (untreated)
2. biochar
3. compost
4. biochar + compost
Row Spacing: 4.5 m
Tree spacing: 1.06 m
Soil type: duplex
Trial establishment
Trees planted: 2 November 2009.
Biochar application (2 Nov 09): - 5 kg biochar per tree 'space' - worked evenly across the row mound into top 10 cm of soil.
Compost application (17 Nov 09): - applied at 10 t/ha as a top dressing - compost donated by Renew
3 tree plot
Field installations
Biochar in
soil profile
TDR probes at 2 depths
Sapflow technology
Soil temperature,
moisture,
microbiology,
density,
compression,
porosity
Tree girth
Flux meters, TDR probes
Fruit yield & quality
Leaf-level gas-
exchange,
Leaf water potential
Climate data (rainfall,
temperature, humidity)
Dataloggers
Assessments
Tree growth
Fruit size (2012)
Fruit quality (2012)
Whole-plant water use
Tree physiology
Control
Biochar
Daily
tre
e w
ate
r use (
L/d
ay)
Soil measurements
Disc permeameter
Taking samples
for bulk density
Soil samples ready for analysis
Leachate sampling
Soil compaction
Soil microbial diversity
Stepwise Discriminant Analysis:
(a) visualisation of the analysis, and
(b) the underlying vectors used to create the visualisation
Biochars are highly porous and stable in
soil potential to provide a direct and
long-term increase in soil porosity
Biochar porosity : 0.844 μm - 235.8 μm
90% of pores less than 22 μm
i.e. within the size range between
permanent wilting point 0.2 μm and
field capacity 30 um
SEM of Acacia green waste
Below ground responses effect of biochar on soil properties
Significantly:
• Reduced bulk density
• Increased total porosity and
saturated water content.
No significant effect on:
• Field capacity
• Permanent wilting point
• Soil moisture
• Near saturated hydraulic
conductivity & Infiltration
• Aggregate stability
• Mesoporosity & Microporosity
Results so far…
Conclusions to date: - improved drainage
- reduction in soil compression / bulk density
- positive effect on growth and fruit size
- increased TSS with biochar+compost
Questions raised: - interactions with type of biochar, climate, soil type etc.
- decrease leaching and better utilisation of nutrients?
- increase efficiencies of chemical inputs (fertilisers)?
- economic feasibility?
- more is not always better?
- beneficial effects more obvious in low-input orchards?
Thanks to a great team that has enabled us to
deliver more than originally planned
And to Adrian and Scott Stevenson for providing
the site and allowing us access at all hours
And finally……
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