Nitrogen use efficient sugarcane
Susanne Schmidt1, Prakash Lakshmanan2, Richard Brackin1, Nicole Robinson1
1The University of Queensland
2Sugar Research Australia
We are exceeding planetary boundaries
2
Algal blooms
Anoxic waters
Polluted ground water
Coastal dead zones
3
Global nitrogen fertiliser efficiency in sugarcane averages ~50%
India
China
USA-Florida
Pakistan
Venezula
Australia
Indonesia
Columbia
Mexico
Brazil
South Africa
Phillipines
Argentina
Thailand
Cuba
Sugarcane accumulates ~50-80 kg nitrogen per hectare
0
100
200
300
400
Average N fertiliser application (kg N per hectare)
Robinson et al. 2011 PLoS ONE
Nitrogen fertiliser drives emissions of greenhouse gas nitrous oxide
kg N-fertiliser per hectare
Emissions factor
6.7
200
100+100
2.9
100
1.1
50+50
1.0
0
0
2
4
6
8
Emissions (kg N2O-N ha-1 y-1)
Allen et al. 2010 Agriculture, Ecosystems & Environment
10
Extent of algal bloom
Nitrogen run-off from
sugarcane fields continues
to pollute the Great Barrier
Reef lagoon
Nitrogen fertiliser is cheap
Farmers apply too much
Commercial sugarcane varieties have not
been bred for N efficiency
Fertiliser dissolves and is
easily lost from soil
Improving nitrogen efficiency
a.
b.
c.
d.
Aligning N supply and crop N
demand
Selecting and breeding N
efficient sugarcane
Legume intercrops for
biologically fixed N
Next-generation fertilisers
Soluble N in soil
Crop N
Early season (∼100 days)
Late season (∼200-300 days)
 ∼50% of crop-N acquired
 fast nitrification and large pool of inorganic N
(ammonium and nitrate)
 high N loss potential
 ∼50% of crop-N acquired
 large pool of organic N
 low N loss potential
Brackin et al. in preparation
N flux studies suggest that ammonium and organic N are the main
N sources for sugarcane
Dr Richard Brackin
Brackin et al. 2015 Scientific Reports
Improving external N efficiency: ability to acquire and store nitrate
3500
3000
2000
leaf
stalk
root
1500
1000
500
0
-500
-1000
-1500
-2000
Qcane
S. spontaneum
Erianthus
Sorghum
-2500
Maize
Nitrate ( µmol plant -1)
2500
Robinson et al. PLoS One 2011
Improving nitrate use with know-how of
molecular mechanisms
a.
b.
c.
d.
Aligning N supply and crop N
demand
Selecting and breeding N
efficient sugarcane
Legume intercrops for
biologically fixed N
Next-generation fertilisers
Commercial sugarcane
Saccharum spontaneum
Saccharum officinarum
Commercial sugarcane
x Erianthus
Erianthus
0
20
40
60
80
100
Nitrate uptake as % of ammonium uptake
Robinson et al. 2011 PLoS One
Improving internal N efficiency
(biomass per unit N)
low N
replete N
Genotype 1
a.
b.
c.
d.
Aligning N supply and crop N
demand
Selecting and breeding N
efficient sugarcane
Legume intercrops for
biologically fixed N
Next-generation fertilisers
Robinson et al. Functional Plant Biology 2007
Whan et al. Functional Plant Biology 2010
Genotype 2
3 year field trials with low (∼40 kg N) and recommended N (∼160 kg N)
 64 genotypes: commercial, foreign, parental lines, introgression crosses
Low N
High N
High N
Low N
Low N
High N
Satellite image January 2013 2nd ratoon, 5 months old crop
Performance at low relative to high N supply identifies efficient genotypes
Yield at low N supply as percentage
of yield at high N supply
(two Australian varieties highlighted among 64 genotypes)
Q186
Q186
Q208
Q186
Q208
Q186
Q208
Q186
Q186
Q208Yiel
Q208
PC
Robinson et al. in prep.
Q208
1R
Site 1
Ayr
2R
PC
1R
Site 2
Mackay
2R
PC Plant Crop
1R 1st ratoon crop
2R 2nd ratoon crop
Selecting genotypes for
efficient N accumulation
Shoot N accumulation (kg N ha-1)
Q186
N uptake ranges
from 40 to 200% of
N-fertiliser
Q208
Low N fertiliser supply (20 kg N ha-1)
Biologically fixed legume-N to complement fertiliser-N
a.
b.
c.
d.
Aligning N supply and crop N
demand
Selecting and breeding N
efficient sugarcane
Legume intercrops for
biologically fixed N
Next-generation fertilisers
Intercropped legumes to reduce N fertiliser needs
Sunshine Coast Australia (2014-15 season)
Salazar et al. unpublished
Nutrient stewardship in a circular economy without waste
and pollution
a.
b.
c.
d.
Aligning N supply and crop N
demand
Selecting and breeding N
efficient sugarcane
Legume intercrops for
biologically fixed N
Next-generation fertilisers
NextGen fertilisers to synchronise N supply and crop demand
Current fertilisers
NextGen fertilisers
Crop demand
Crop demand
crop season
crop season
20
Traditional fertiliser
Nutrients dissolve quickly
and can be lost from soil
if not acquired by crops
NextGen fertiliser
Nutrients are bound to
sorber matrix and
released at rate of
crop acquisition
Image courtesy Dr Paul Luckman, UQ
Re-imagine fertilisers with understanding of rhizosphere processes, new materials and
re-purposed wastes from sugar mills
Brackin et al. 2015 Nutrient fluxes at the root-soil interface show a mismatch of N fertilizer supply
and sugarcane root uptake capacity Scientific Reports
nextGen fertilisers based on re-purposed wastes and
sorbers
Barren pellet
Nutrient loaded pellet
Agronomy and genetic improvements to contribute to nutrient
stewardship and sustainable sugarcane cropping
Terima kasih