can we use ert to measure root zone competition in fields ... · universite de liÈge gembloux...
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UNIVERSITE DE LIÈGE Gembloux Agro-Bio Tech
Can we use ERT to measure root zone competition in fields with multiple
crops? S. Garré, I. Coteur, C. Wongleecharoen, K. Hussain, W. Omsunrarn,
T. Kongkaew, T. Hilger, J. Diels, J. Vanderborght A collaboraDon of
KULeuven, Hohenheim University, Kasetsart University, FZJülich
• YES, but…
YES Can we use ERT to measure root zone compeDDon in fields with mulDple crops?
• YES, but…
YES BUT… Can we use ERT to measure root zone compeDDon in fields with mulDple crops?
YES
Ratchaburi Province
ERT measurements
Climate
bare soil
maize monocropping
maize, chili, Leucaena intercropping
+ ferDlizer
+ ferDlizer -‐ ferDlizer
TDR probe Electrode maize chili Leucaena
13 m
4 m
4 contrasted cases
BS MC+ IC+ IC-‐
Soil moisture depleDon
BS MC+ IC+ IC-‐
WC ΔWC
06/08 -‐ 18/08 -‐ 21/08 -‐ 27/08
-‐ 15/09
Water depleDon during growing season
Dme Dme Dme
plant row
s
Up hill Down hill
MC+ IC+ IC-‐
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Water depleDon f(distance to hedge)?
Water depleDon vs. plant performance
Graphs Khalid
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(cm) (cm) (cm)
MC+ IC+ IC-‐
Air: constant raDo of carbon isotopes (R) No stress: same raDo 13C/12C in plant cells Water stress: stomata close -‐> fracDonaDon by diffusion -‐> discriminaDon against 13C by enzyme RuBisCo -‐> leaky bundle sheath cells N stress: photosynthesis is shut down
-‐> less discriminaDon against 13C
∂13C =RsampleRPDB
−1#
$%
&
'(x1000 with R =
13C12C
δ13C
δ13C
δ13C ≅-‐13
Carbon isotopic raDo of C4 plants
Grain carbon isotopic raDo (δ13C)
MC + IC+ IC-‐
δ13C increase -‐> compe66on for N!
YES … we can retrieve palerns of water depleDon … we can quanDfy differences between cropping systems … combinaDon with δ13C techniques: nature of compeDDon can be idenDfied
YES … we can retrieve palerns of water depleDon … we can quanDfy differences between cropping systems … combinaDon with δ13C techniques: nature of compeDDon can be idenDfied BUT…
BUT… • Detailed experimental design is necessary. Garré et al. (2012) VZJ 11 (4)
• UncertainDes in conversion WC = f(EC, ...) Garré et al. (2013) VZJ 12 (2)
BUT… UncertainDes in conversion WC = f(EC, ...)
Injected current Measured voltage
ELECTRICAL CONDUCTIVITY
Temperature Different hea=ng under different crops
Pore water concentra6on Assump=on of ± cte concentra=on Sufficient aIer rain events? Water content
Surface conduc6vity Structures + Heterogeneity!
INVE
RSION
PEDO
PHYSICAL
RELATIONSH
IP
Garré et al. (2013) VZJ 12 (2)
0 2.5 x (m) 7.5 10 12.5
−4
−3
z (m)
−1
0BaR3
0 2.5 x (m) 7.5 10 12.5
−4
−3
z (m)
−1
0T1R3
0 2.5 x (m) 7.5 10 12.5
−4
−3
z (m)
−1
0T4R3
0 0.01 0.02 0.03
0 2.5 x (m) 7.5 10 12.5
−4
−3
z (m)
−1
0T6R3
ECb,25 (Sm−1)
Example: Heterogeneous profiles
0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 0.0220.1
0.15
0.2
0.25
0.3
0.35
0.4
ECb,25 (Sm−1)
WC
(−)
Data horizon 1Data horizon 2Horizon 1: RMSE=0.0011Horizon 2: RMSE=0.0008
BS MC+
IC+ IC-‐
Pedophysical funcDons for 2 horizons
Not so easy to delineate horizons in the profile
YES!
Conclusion
BUT… further research!
©Seth, street art Paris
Can we use ERT to measure root zone compeDDon in fields with mulDple crops?
My sincere thanks to Ine Coteur Prof. Jan Diels Prof. Jan Vanderborght Prof. Thanuchai Kongkaew+
Walanai Omsunrarn Channarong Khetdan Khalid Hussain Thomas Hilger Chalemchart Wongleecharoen Marc-‐André Sparke
© Os G
emeo
s, street art Grolaglie