Involving leguminous crop rotation as climate …...Climate Adaptation 2014: Future Challenges...

Climate Adaptation 2014: Future Challenges WWW.DPI.NSW.GOV.AU

Involving leguminous crop rotation as climate change adaption option

also as lower nitrous oxide emissions from dryland cropping

Yuchun Ma1,2,3, Graeme Schwenke4, Bin Wang1,5, De Li Liu1,2, Muhhuddin Anwar1,2

1 NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia

2 Graham Centre for Agricultural Innovation, PMB, Pine Gully Road, Wagga Wagga, NSW 2650, Australia

3 College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, Jiangsu 210044, China

4 NSW Department of Primary Industries, 4 Marsden Park Road, Tamworth, NSW 2340, Australia

5 Plant Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia


Background

IPCC 2013

History Future

RCP2.6

RCP8.5


IPCC 2013

History Future


Since 1970s, N2O has increased at an

average rate of ~0.75 ppb yr–1

Agricultural soils are known to be the

major anthropogenic source of N2O.

The agricultural sector contributes 80%

of total N2O emissions of Australia.


Cereal/oilseed crop production accounts for more than 70%

of the total N fertilizer use in Australia


What should we do

to adapt

the climate change


N-fertilized crops: Data have been

restricted to trials where only N

fertilizer was used.

Legume crops: Data come from

systems where either no N fertilizer

was used, or legumes were supplied

with just 5 kg fertilizer-N ha-1


The aim is to examine whether cropping rotations with legumes as

adaptation options to climate change can reduce N2O emissions.

An alternative is to incorporate leguminous crops into

cereal cropping rotations to provide a biological source of N


Material and method

Field experiment

CpWB: chickpea-wheat (80 kg N ha-1) -barley

CaWB: canola (80 kg N ha-1)-wheat (80 kg N ha-1)-barley (60 kg N ha-1)

Mean temperature 17.2 oC Annual rainfall 705 mm


By using a fully automated closed

chamber monitoring system, we

tested the mitigation potential of

the legume-involved rotations at

the field scale.

Using the date from field to

validate DNDC model.

Climate scenarios (AR5 scenarios):

By using DNDC model to evaluate

the long-term effects of the legume

rotations on mitigation and

adaptation under climate change

scenarios in northern Australia.

Future simulate Observe Validate DNDC


Climate scenarios: RCP 4.5 with radiative forcing stabilized shortly after 2100 scenarios RCP 8.5 with very high greenhouse gas emissions (adopted based on the Intergovernmental Panel on Climate Change (IPCC) fifth Assessment Report (AR5) ) Climate data of RCP 4.5 and RCP 8.5 A weather-generator statistical downscaling method (Liu and Zuo, 2012, Liu et al.,

2014) was utilized to downscale IPCC AR5 GCM (CSIRO Mk 3.6) projection under

the RCP 4.5 and RCP 8.5 scenarios to yield the daily climate data for the period of

1960-2100.

Historical climate data for the period of 1960-2013 were obtained from the SILO Patched Point Dataset and were used for two purposes: ①The data for the period of 1960-2000 were used to establish the relationship between CSIRO-Mk3.6 simulated climate and the measured historical climate for bias-correlation as described by Liu and Zuo (2012). ②The period of historical 1961-2010 were used as a baseline to run DNDC model for simulating the discrepancy of N2O emissions and grain yields under current climate.


(Although the downscaling approach incorporates a bias-correlation, the downscaled daily climate is still needed to demonstrate agreement with site measured data)

No clear trends for precipitation Air temperature increased


Rainfall event +Fertilization event

R2>0.95 good performance for these site-specific rotation systems


1、Ob~Si p<0.001 2、WFPF~N2O p<0.001

WFPS→N2O Mineral N contents→N2O

WFPS>70% Most time <20 mg N kg-1 except the peaks of N2O emission


Both the observations and simulations show less cumulative N2O emissions from the CpWB

compared to the CaWB rotation.

① greater amounts of residue N

② the high rate of canola litter incorporation and the following mineralization processes during the post-harvest fallow

season

③ the legume crop prefers to absorb the soil mineral N before it fixes atmospheric N., increased the NUE

29% 1%

0.31 kg N 0.24 kg N

<<


The prediction errors of cumulative N2O emissions and grain yields for the two rotations were less than 10% of the observed values

(189 kg ha-1 for grain yield which was 6% of observations; 0.006 kg N ha-1 for N2O emissions which was 1% of observations).

Long-term impact of the legumes adopted in the rotation was simulated by running DNDC for 87 years

39%

74%

2%

5%

3%

12%


Conclusions ① N2O emissions from the two rotation systems under the two climate scenarios would

gradually increase;

② the increasing rate of N2O with the CpWB rotation with legume would be much lower

than that with the CaWB rotation without legume crop (39% vs. 74% increase for CpWB

and CaWB, respectively).

③ In comparison with CaWB, CpWB decreased the yield-based N2O-N emission rate by an

average of 22% under the two RCP scenarios.

Our conclusion is that involving legume crops in the rotation

systems could be a promising strategy to mitigate N2O emissions

from the rain-fed cropping systems in the northern Australian

grain growing region.


Acknowledgement

NSW Department of Primary Industries made the opportunity for the

senior author to visit Graham Centre for Agricultural Innovation. The

funding support from Australian Government (Department of Agricultural,

Fisheries and Forestry) and NSW Department of Primary Industries for

this work is greatly acknowledged.


IPCC 2013

Involving leguminous crop rotation as climate …...Climate Adaptation 2014: Future Challenges...

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