A analyis of different energy fluxes and CO2 was performed with the data available from a maize field from north west of stuttgart. The measurements were taken witht the help of Eddy Covariance technique.

1. Analysis of energy and CO2 fluxes during
the different growth periods of maize
Environmental Science Project SS 2011
Wolfram Buß, Renqing Du, Johanna Hemetzberger, Anubhav Mohiley, Aditya Parmar, E. M. Hassan Sarker
1. Introduction 4.1 Results and Discussion
Biosphere and atmosphere interactions in terms of
mass and energy transfer have a great relevance in
the change of climatic conditions. The knowledge of 1
the variation in these fluxes at local scale is important 2
for the creation of weather and climate simulations.
2. Objective 3
The main objective of the study was to analyze the
variation of energy and CO2 fluxes during different
4
growth periods of maize.
Fig. 3: Canopy height and CO2 flux with respect to five growth periods
3. Material and Methods 5
 Experiment Site: Maize field (200 x 200m) in the  Energy Balance Closure: 86.7% (Fig.2)
Fig. 1: Eddy covariance station
Kraichgau, North-West of Stuttgart from May to 1 Ultrasonic Anemometer  Fig.3 illustrates inverse relationship between
September 2009 2 CO2 & H2O Infrared
plant biomass production and CO2 flux
Spectrometer
 Parameters & Equipment: CO2 flux, Latent, 3 Hygrometer & Thermometer  Assimilation of CO2 exceeds respiration part
Sensible, Ground fluxes and Net Radiation with 4 CO2 & H2O gas analyzer
5 Data storage and analysis during growth stages when plant is
Eddy Covariance technique (Fig.1) accumulating biomass in form of LAI and yield
 Data Correction: Software Tool TK2  Respiration dominates again during final
 Energy Balance Closure was performed (Fig.2) stage, as negligible biomass production takes
 Identification of different growth periods for maize place (Suyker et al. 2004)
using FAO crop water information model  Hourly patterns of energy fluxes and BR are
 CO2 and canopy height were related with different characterized in Fig.4 and Fig.5 with respect
growth periods (Fig.3) to different growth stages
Energy balance closure 86.7%
 Hourly patterns of energy fluxes were plotted for  Hourly patterns give an indication that all
RN = H + λE + G
each growth period RN: Net radiation
G
23.2 energy fluxes are tagged with the net radiation
 Bowen Ratio (BR) hourly and stage wise H: Sensible heat
λE: Latent heat
%
 Raised BR during highest net radiation of day
calculations were done ������ ������������������������������������������������ ℎ������������������
G: Soil heat
stipulates stomata closure to prevent water
������������ = =
������ ������������������������������������ ℎ������������������ Fig. 2: Energy balance
losses (Xi et al. 2009)
Fig. 4: Energy fluxes for different growth periods of maize
4.2 Results and Discussion 5. Conclusion
 Energy fluxes and BR variations during different The flux of CO2 between
growth stages are explained by physiological biosphere and
changes which take place during different stages atmosphere as well as
 Progressive increase in LAI and assimilates in the partitioning of the net
form of yield, contribute to a higher latent heat flux radiation into different
during the flowering and yield formation stages energy fluxes depend on
 Higher stomatal conductance is needed for CO2 the growth periods of
fixation which results in latent heat increase maize. C3 and C4 crop
 During the biomass production BR diminishes as fields show lots of
the latent heat part increase during those stages similarities in their energy
(Prueger et al. 2004) partitioning and CO2 flux
 Sudden increase in BR is observed (Fig.5) in the behavior, apart from
Fig. 5: Bowen Ratio with respect to growth stages
final stage as biomass production stops some shifts in response
 However, latent heat is dominating during the due to physiological
whole vegetation period (Ingwersen et al. 2011) differences.
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