Quantitative Evaluation of the Native Fertility of Tropical Soils

An implementation of the QUEFTS (Quantitative Evaluation of the Native Fertility of Tropical Soils) model. The model (1) estimates native nutrient (N, P, K) supply of soils from a few soil chemical properties; and (2) computes crop yield given that supply, fertilizer application and crop parameters. See Janssen et al. (1990) for the technical details and Sattari et al. (2014) for a recent evaluation and improvements.