Unlocking the true value of organic soil amendmentsDavid Rowlings,

Ian Porter, David Riches, Scott Mattner, Daniele De Rosa, Johannes Biala, Wendy Quayle

The Nitrogen dilemma - A very leaky element

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0N LN MN HN 0N+C LN+C MN+C HN+C

DM

yie

ld (

kg h

a-1) Soybean

Year 1

Year 2

Lassaletta et al., 2014

Lu and Tian, 2017

N fertiliser rate

• Intensive animal industries in Australia produce >3 million t/yr

• Contains 246,000 t of N, 88,000 t P & 359,000 t of K• Valued at $1.9 billion/yr

• Few operations but large, centralised operations (e.g. >25 000 head of cattle) • Majority as poultry and beef feedlot

• Transport is major cost for use > 150 km economical?

• Wide price range – $12/t raw feedlot → >$85/t composts

• Nutrient and liming value up to $160/t• Co-benefits?

• Storage and processing largely unregulated

• Little incentive to minimise losses

• None for application

A great resource: Organic Amendments (OA) in Australia

Beef City, feedlot Queensland

1. The product: How manure product is handled, stored, blended

So what’s the issue?

• Age

• Weather/exposure

• Stockpiled, composted, turned, blended with carbon sources

• Large potential nutrient losses – particularly nitrogen

• Estimated $700k yr-1 of N lost from this single composting operation

→ highly variable end product: what are you paying for?

Composting period →

NH

3lo

sses

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l N a

pp

lied

(kg

ha)

Total Nitrogen supply from 10 t (ww) dairy manure

2016 2018 2019 2020

2. How much OA to apply?

So what’s the issue?

Manure needed to apply 35 kg N ha-1 of available N upfront

Stockpiled/Raw CM: 3.5 t/haComposted CM: 19.0 t/ha

Stockpiled/Raw FM: 2.5 t/haComposted FM: 34.0 t/ha

Target nutrient

input

Urban-derived

compost

Feedlot manure Composted chicken manure

Application rate - Wet weight (tonne ha-1) - 29 16.5 6

Application rate - Dry weight (tonne ha-1) - 21.3 13.3 4.6

Total P (kg ha-1) 70 70 70 70

Total N (kg ha-1) 300 336 158 199

Total K (kg ha-1) 180 216 227 118

What about available (mineral) N?

→ How do we avoid excess nutrients

3. When is that nitrogen available (nutrient release curves) and matching plant demand

→Multiple applications

So what’s the issue?

Crop 3

Compost app

Crop 2

7

Right balance between OAs and chemical fertilizer Accounting for the Plant available N (PAN) release from OA

Accounting for Nitrogen

8

Accounting for the Plant available N (PAN) release from OA Right balance between OAs and chemical fertilizer

Accounting for Nitrogen

What happens when we get it wrong?

So what’s the big issue?

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Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepD

aily

N2O

em

issi

on

s (g

N h

a-1d

ay-1

)

Daily N2O emissions Chicken Manure

N lo

sses

N lo

sses

Additional benefits – Soil Health

Treatments that received COMPOSTED OAMaintain or increased SOC

Treatments that received RAW OADecreased SOC (-3.4% year)

• Increased Nitrogen use efficiency• Increased water use efficiency• Increased infiltration/lower erosivity• Pathogen resistance• Soil C sequestration

Intensive vegetables - Gatton

Maintaining Long-term Soil Carbon

Hard to quantify

Smart Farming partnerships: From waste to fertiliser – a farmer ready tool for the effective integration of manures and composts into farm fertiliser budgets for improved environmental, soil health and economic sustainability

Predicting plant nutrients release from soil organic amendments

Laboratory analysis

Model parametrisation

Field validation

calibration

SOIL

PREDICT

CLIMATE

OA

MANAGEMENT

SYSTEM

OA

OA NUTRIENTSOA NUTRIENTS

BUDGET

Mineral Nitrogen kg/ha

•DEC-FEB

•MAR-MAY

•JUN-AUG

•SEP-NOV

AVALABLE P kg/ha

•DEC-FEB

•MAR-MAY

•JUN-AUG

•SEP-NOV

AVALABLE K kg/ha

•MAR-MAY

•MAR-MAY

•JUN-AUG

•SEP-NOV

SAVE

?!?! NOTES

#%#%#%#%

#%#%#%#%

Y1 Y2

#%#%#%#%

#%#%#%#%

#%#%#%#%

#%#%#%#%

Y1 Y2

Y1 Y2

Back

Predicting plant nutrients release from soil organic amendments

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OA Nitrogen supply

UD Compost Pig manure Compost Raw chicken litter

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l N a

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OA Phosphorus supply

UD Compost Pig manure Compost Raw chicken litter