Nitrogen-limited production

Exercise objective:

·    Understanding effects of nitrogen deficiency on crop growth and yield.

Suggested reading:

The theory of nitrogen-limited production is explained in Chapter 5 of the book, ORYZA2000: modelling lowland rice.

This mode of simulation can be used to study the effects of nitrogen limitations on crop growth, and the effects of soil nitrogen supplying capacity and nitrogen fertilizer applications. This set of exercises illustrates the simulation of crop growth and development with a nitrogen balance. Here, crop growth is not only governed by crop characteristics and the weather variables radiation and temperature, but also by nitrogen supply. It is still assumed that the crop is optimally supplied with water and other nutrients (potassium, phosphorus and all necessary micronutrients), and that there is no yield reduction caused by weeds, pests or diseases.

Exercise: 

In the examples, we simulate the 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 validated by comparison with observations on actual crop growth and development in a field experiment with different nitrogen levels. Box III.1 gives the details of the experiment (same as Box II.1 in “Chapter II: Potential production”).

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

·    Nitrogen management

         Exercise objective:

        ·   Manipulating nitrogen (N) management in the experimental data file.

         Suggested reading:

         Chapters 7.2 (the part on N management) of the book, ORYZA2000: modelling lowland rice.

         Click HERE for learning exercises on Nitrogen management.

·    Sensitivity analysis 

         Exercise objective:

        ·  Sensitivity to and interaction among N management parameters.

         In these short exercises, we will examine the sensitivity of ORYZA2000 to the N-management characteristics

         in the experimental data file, and their interacting effects.

         Click HERE for learning exercises on Sensitivity analysis.