A simulation of the accumulation of mineral nutrients in crops by an allometric model dependent on thermal time (non-linear) is proposed as a simple and robust method to calculate and schedule crops fertigation. Crop accumulation of nutrients was calculated by the allometric relation between nutrients and biomass, coupled to a biomass function dependent on a biological age. Thus, a curve for nutrient accumulation can be characterized with six specific parameters, including the allometric exponent. Three data sets were employed to verify simulations. Fit parameters were obtained, being R2 > 0.9 for four of the five main macronutrients. When verifying the simulation ability, RMSE were: nitrogen (N) = 0.1355; phosphorus (P) = 0.1214; potassium (K) = 0.1179; calcium (Ca) = 0.0991 and magnesium (Mg) = 0.0821 (relative data). The proposed allometric method describes the nutrients accumulation with remarkable simplicity and flexibility, while the verification of the model was done on three differing experimental conditions simultaneously.