Potential production

Exercise objective:

·   Understanding effects of crop characteristic and environmental conditions on potential production.

Suggested reading:

The theory of potential production, as explained in Chapter 3 of the book, ORYZA2000: modelling lowland rice.

This set of exercises illustrates the manipulation of the crop data file to simulate potential production of a specific rice variety, characterized by its genetic properties. This mode of simulation can be used to study effects of weather and varietal characteristics on potential production. In situations of potential production, crop growth is only determined by crop characteristics, the weather variables radiation and temperature, and the daylength (as computed by ORYZA2000 from the day of year and the geographical location of the weather station). It is assumed that the crop is optimally supplied with water and nutrients, and there is no yield reduction caused by weeds, pests or diseases. In ORYZA2000, the nitrogen balance and the soil water balance are not activated when the simulation is carried out in the POTENTIAL PRODUCTION mode.

In the exercises, we simulate the potential growth and development of rice variety IR72, in the dry season of 1992, using weather data from the IRRI farm in Los Baños, the Philippines. The simulation results are checked against observations on actual crop growth and development in a field experiment comprising different nitrogen levels. Box II.1 gives the details of the experiment. In the following exercises, we will mainly use the observations on the treatment with the highest nitrogen level (Treatment level 2 in Box II.1), since this treatment is expected to most closely approach the potential production situation. This data set is the same one as used in the exercises in ‘Navigation: Exploration mode’.

Box II.1. Experimental details of potential production field experiment.

• Crop characteristics

Exercise objective:

·   Potential production; the crop characteristics in the crop data file

Suggested reading: 

Chapters 7.3 and 8.2 of the book, ORYZA2000: modelling lowland rice.

Click HERE for learning exercises on Crop characteristics.

• Forcing functions 

Exercise objective

·   Overruling simulated with observed values: forcing functions.

Suggested reading

Chapters 2.3, 4.1, 7.5 of the book, ORYZA2000: modelling lowland rice.

Click HERE for learning exercises on Forcing functions.

• Potential evapotranspiration

Exercise objective

·   Selecting evapotranspiration modules and availability of weather data. 

Suggested reading

Chapters 2.3, 4.1, 7.5 of the book, ORYZA2000: modelling lowland rice.

Click HERE for learning exercises on Potential evapotranspiration.