Impact of nutrient addition

Carbon and water fluxes in crops:

Phil Ward, Ian Fillery and Shayne Micin

5 July, 2012

PLANT INDUSTRY / SUSTAINABLE AGRICULTURE FLAGSHIP

Project information

Carbon and water fluxes of crops | Ian Fillery

“Maximizing crop yield in the HRZ of WA through efficient use of water and nutrients”

Focus on region between Perth and Albany, WA

Annual rainfall 450-650 mm

July 2010 to June 2013

WUE of cereals and rotations

Experiments commenced in 2010

•Crop production is expanding into previously ‘too wet’ areas

Rainfall concentrated in winter months – waterlogging

• Potential for grain yields >6 t/ha, but actual yields are about 3 t/ha

•Conservative management, or poorly adapted varieties?

•Source or sink (head size) constraining crop grain yields?

•Investigate role of canopy size and growth rate on daily water use and carbon uptake at the paddock scale – to use data collected to critically appraise APSIM (cropping system model)

The issue

Carbon and water fluxes of crops | Ian Fillery

Landscape

Carbon and water fluxes of crops | Ian Fillery

Gently undulating, occasional lone eucalypts

Site layout

Carbon and water fluxes of crops | Ian Fillery

100 m

NMM Access tube

Eddy covariance etc

TDR probe

Rain gauge

100 m

2010

Wheat sown on June 10

Nitrogen applied:

June 10 - sowing

13 kg N/ha to both plots

July 20 - 4-leaf stage

28 kg N/ha to west only

September 3 - 1st node

28 kg N/ha to both plots

Treatments

Carbon and water fluxes of crops | Ian Fillery

2011

Canola sown on May 4

Nitrogen applied:

May 4 - sowing

13 kg N/ha to both plots

August 18 - bolting

74 kg N/ha to west plot

37 kg N/ha to east plot

2012

Wheat

TBA

Nitrogen application

Carbon and water fluxes of crops | Ian Fillery

Measurements

Carbon and water fluxes of crops | Ian Fillery

Leaf to plot to paddock scale CO2 and water flux

– Eddy covariance using

Licor LI-7500 and R3-50 sonic

anemometer (Gill Instruments, UK)

– Chamber system

Leaf (canopy) temperature using IR sensors and air temperature

Leaf area and dry matter (every 2 weeks)

Soil water content

– NMM, TDR, HH TDR

Carbon and water fluxes of crops | Ian Fillery

Seasonal conditions – Kojonup P.O.

Average 2010 2011

Annual 529 348 691

May - Nov 431 219 491

0

20

40

60

80

100

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

Monthly rainfall (mm)

2010

2011

Average

Wheat density and yield - 2010

Carbon and water fluxes of crops | Ian Fillery

Early N Late N

Plant density (/m2) 92 88

Yield(t/ha) 2.1 1.9

Dry matter (t/ha) 4.7 4.1

Harvest Index (%) 45 46

1000 grain weight (g) 33.3 34.6*

Significant differences identified by * in the ‘Late N’ column

Crop growth and leaf area

Carbon and water fluxes of crops | Ian Fillery

0

1

2

3

4

5

Jun Jul Aug Sep Oct Nov Dec

Dry matter (t/ha)

Early

Late

* **

0

0.5

1

1.5

2

Jun Jul Aug Sep Oct Nov Dec

Green leaf area index

Early

Late

** *

Sow N1 N2 Sow N1 N2

Paddock-scale water use

Carbon and water fluxes of crops | Ian Fillery

0

40

80

120

160

200

31/05/2010 31/07/2010 30/09/2010

Cu

mu

lati

ve

wa

ter

us

e

or

rain

fall (

mm

)

Late N

Early N

Rainfall

Potential ET

Sowing date

N application dates

Total daily ET

Carbon and water fluxes of crops | Ian Fillery

* *

* *

* *

* * *

* * *

* * *

*

Paddock-scale net CO2 uptake

Carbon and water fluxes of crops | Ian Fillery

-10

-8

-6

-4

-2

0

2

31 May 1 Jul 1 Aug 1 Sep 2 Oct 2 Nov

Net carbon uptake

(t CO2/ha) Late

Early

Sowing date

N application

Net daily CO2 flux

Carbon and water fluxes of crops | Ian Fillery

*

* *

* * *

Day and night CO2 flux

Carbon and water fluxes of crops | Ian Fillery

* * * *

* *

* * * *

* *

* * *

* *

* *

* * *

* * * * * * *

* *

After N addition:

• Significant difference in above-ground biomass and LAI seen after 6 weeks.

• Significant difference in ET observed after 4 weeks i.e. before visible differences were seen in above-ground crop growth.

• Significant differences in daytime and night time CO2 fluxes were observed after 2 weeks, but differences were in opposite directions. Net daily fluxes were largely unaffected until 6 weeks after N application.

Dry seasonal conditions make it difficult to answer the ‘source or sink’ question, but these results demonstrate the ability of Eddy Covariance to discriminate between N fertiliser treatments.

Nitrogen application increases net CO2 uptake.

Does increased use of nutrients improve sequestration of C in soil?

Conclusions

Carbon and water fluxes of crops | Ian Fillery

One more year of data collection

Wheat, early vs late nitrogen

Canopy temperature

Any good infra red sensors out there? Ours keep failing!

Crop stress and transpiration

Good data for modelling

Daily data for daily crop models

Plans for 2012

Carbon and water fluxes of crops | Ian Fillery

Thank you

PLANT INDUSTRY / SUSTAINABLE AGRICULTURE FLAGSHIP