To assess the suitability of the land for selected crops, the soil attributes and land qualities are compared with the individual crop requirements for optimum growth. For Vanuatu, these have been derived using the VANRIS dataset and crop requirement files associated with the Plantgro software package (a now deprecated CSIRO programme).
Hackett, C. (1991a). "Plantgro - A Software Package for Coarse Prediction of Plant Growth". (CSIRO: Australia.)
For each of the 78 crops assessed, the soil-plant relationships in the Plantgro plant files were modified to assign suitability ratings (1 excellent to 9 crop dies), according to 11 of the classified soil attributes from the VANRIS system (i.e., slope, rooting depth, drainage class, soil texture, pH, total Nitrogen, Available Phosphorus, Exchangeable Potassium, Base Saturation, Cation Exchange Capacity and Salinity).
These plant requirement relationships as presented in the Plantgro plant files were then converted to a GIS lookup table format and at the same time the Plantgro suitability ratings converted to FAO Land Suitability Ratings (S1, S2, S3, N1 and N2).
Finally, the lookup tables were joined to the VANRIS dataset, and an FAO suitability rating for each crop and soil property assigned to each polygon in the dataset. The maximum limitation (most limiting factor) was then assigned to that polygon.
Please use these suitability ratings as a first approximation. As stated in the Plantgro files:
By use of FAO's ECOCROP database, a FIRST ESTIMATE has been made of this species' responses to soil and climate factors. Testing and improvement MUST BE DONE if the file is used for serious work. USERS BEAR ALL RESPONSIBLILITIES FOR ALL ERRORS OF ANY KIND.
