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……