WaNuLCAS a model of Water, Nutrient and Light Capture in Agroforestry Systems

WaNuLCAS a model of Water, Nutrient and Light Capture in Agroforestry Systems

Sustainable land use systems can be provided through agroforestry practices. Agroforestry is an agricultural approach of using the benefits from combining trees and crops and/or livestock. Therefore, knowledge on selection of species combination and good management of trees and crops are needed to maximize the production and positive effects of trees and to minimize negative competitive effects on crops. However, empirical assessment of tree crop combinations is laborious, cost expensive and time consuming. One method for overcoming this lack of information is through development of model which integrate soil-tree-crop interaction between components of agroforestry.

The WaNuLCAS model was developed to represent tree-soil-crop interactions in a wide range of agroforestry systems where trees and crops overlap in space and/or time (simultaneous and sequential agroforestry).

The model is based on above and below ground architecture of tree and crop, elementary tree and crop physiology and soil science (daily water, N, P and SOM balance for 4 soil layers and 4 horizontal zones).
The model was developed in the Stella modeling platform and can be used to assess the performance in terms of profitability as well as sustainability of various agroforestry systems.

The model is conceived as four layers of soil exploited by roots of two components: a crop and a tree. A simple vertical water balance is maintained on the basis of precipitation entering the top layer and drainage leaving the bottom layer. Water leaching downwards carries nutrients, based on the current average concentration in soil solution. Each layer of soil has its own potential uptake of water and nutrient; actual uptake is based on a comparison of the summed potential uptake from all layers and the current 'demand' as determined by the plant biomass. Plant growth is limited by light supply as well as the minimum of relative nutrient and relative water uptake. The two plants interact primarily via the belowground resources and also by shading.

To use the model you need to:

  1. Download the model files
  2. Obtain a copy of the STELLA modelling software (either the commercial run time = CRT version or demo version). The current version was built using Stella Research version 7.
  3. A documentation of relevant presentation and manual of the model is available as a set of pdf and powerpoint files.
  4. Read and agree on the Disclaimer and Copyright.