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. A manual approach was taken for matching soil map units and crop requirements with land qualities. This approach produced robust results and gave sensible estimates for the crop suitability of the 50+ crops for the 193 soil map units.
Crop suitability ratings were determined for each soil map unit defined for Tonga for the following crops:
Cassava, Giant Taro (Kape - Alocasia), Kava, Kumala, Potato, Taro (Talo Futuna - Xanthosoma and Talo Tonga - Colocasia) and yam
Beans, Carrot, Cabbage, Eggplant, Lettuce, Pumpkin, Squash, Sweet Corn, Tomato and Zucchini
Breadfruit, Citrus, Coconut, Coffee, Guava, Mango, Noni, Paper Mulberry
Banana, Papaya, Peanut, Pineapple, Vanilla, Watermelon
Crop Suitability Class rating system
Class 1 Highly suitable
Without significant limitations.
Class 2 Moderately suitable
Suitable but has limitations that reduce productivity or increase the inputs needed to sustain productivity.
Class 3 Marginally suitable
Limitations so severe that benefits are reduced and/or the inputs needed to sustain production are increased so that this cost is only marginally justified.
Class 4 Not suitable