RAL has been engaged with the research community to develop an integrated modeling system that captures interactions between weather, climate, crop growth, urbanization, and hydrology. Developing the integrated WRF-Crop modeling system involves two steps: 1) coupling the Noah-MP photosynthesis and soil hydrology components with crop-growth models, and 2) developing crop-specific parameters required by crop-growth models.

Predicted crop leaf area index (LAI) for an Illinois (corn and soybean rotation) site.
Predicted crop leaf area index (LAI) for an Illinois (corn and soybean rotation) site. 

The crop-growth models are intended to simulate phenological development, growth and yield formation from emergence until maturity using crop genetic properties, weather, and soil conditions following methods developed and adapted in the agriculture communities. Simulated processes include phenological development rate, gross CO2 assimilation, maintenance respiration, dry matter partitioning for biomass accumulation, growth and senescence of leaves, extension of roots, and crop yields. WRF-Crop incorporates a database on crop characteristics per species, which, for instance, includes the following crop-specific characteristics:

  • Specific leaf area as function of development stage.
  • Emergence: sow date, temperature threshold from sowing to emergence, initial crop dry weight, leaf area index at emergence. 
  • CO2 assimilation characteristics of a single leaf: initial light efficiency, rate of net or gross CO2 assimilation at light saturation, respiration in the dark.
  • Conversion efficiency of the sugars produced in the assimilation process into leaves, stems, roots, and grains.
  • Seasonal partitioning of newly formed dry mass into leaves, stems, roots, and grains. Note that the fraction of total dry matter to various plant parts depends on plant development stages. 
  • Maintenance respiration rate.
  • Initial rooting depth and maximum rooting depth.
  • Death rate of leaves, roots, and stems.