Dataset

We have two datasets from an experiment conducted in 2005 with maize plots under multiple levels of nitrogen application.

SPAD

Gas Exchange

Recalculate stomatal conductance in units that our model uses for taking account air pressure.

Make a combined dataset.

Model

Gas exchange model is mostly derived from MAIZSIM, adapting to Cropbox framework.

SPAD - N

We have a quadratic relationship $N = 0.0004S^2 + 0.0120S$. Note that intercept (SNc) is close to zero.

Environment

C4

Interface

Boundary Layer

Stomata

Ball-Berry Model
Medlyn Model

Intercellular Space

Energy Balance

Coupling

Default parameters are mostly from MAIZSIM.

For simplicity, environmental inputs are set as parameters, instead of driving variables loaded from external data frame.

Calibration

Since our model generally performed well under nitrogen non-limiting condition, we decided to keep the most of existing parameter set and calibrate only a small set of parameters. We will calibrate two parameters (s, N0) for nitrogen dependency along A_net and two parameters (g0, g1) for stomatal conductance along gs.

Result

Photosynthesis

Stomatal Conductance

Temperature

Analysis

Ball-Berry vs. Medlyn

Photosynthesis

Ca
Ci
Ta
RH

Stomatal Conductance

Ca
Ci
Ta
RH

Surface Humidity

Leaf Temperature

Stress Response

Nitrogen Stress

Relative Humidity

CO2

Air Temperature

Irradiance

Water Stress

Relative Humidity

CO2

Air Temperature

Irradiance

Stress Interaction

RH

CO2

PFD

Extras

Nitrogen Parameter Sensitivty

Kubien Replicates

Initial

Ball-Berry
Medlyn

Final

Ball-Berry
Medlyn

Sample Code