In the semiarid southern coast of Puerto Rico at the Fortuna agricultural experiment substation, Juana Díaz, we conducted a study on N, P and K uptake by nitrogen fertigated sweet peppers (cv. Cubanelle) and growth parameters (fresh and dry weight of plant, fresh and dry weight of fruit). The treatments were T1 = 500, T2 = 300 and T3 = 150 kg of N per hectare in 11 applications via drip irrigation, T4 = 500 kg of N/ha banded, T5 = control, replicated four times in a complete randomized split plot design. Nitrogen source was urea. The subplots were used for plastic mulched and nonmulched plots. The relationships between N, P, K and growth parameters versus days after transplanting were determined by the equation Y = A/(B + (C-X)2, a Mitscherlich curve type. These relationships indicated 5 phases of nutrient uptake. Coefficient of determination varied from 0.55 to 0.85 for growth parameters and from 0.70 to 0.99 for nutrient uptake. Nutrient uptake values were significantly higher in the last one-third of the growing cycle. The commercial pepper yield was 46.8, 51.2, 43.1, 31.0 and 20.8 tons/ha with plastic mulching compared with 26.2, 34.6, 27.9, 25.9 and 14.8 tons/ha with no mulching in the T1, T2, T3, T4 and T5 plots, respectively. Fertigation with 300 kg/ha of N produced a higher commercial yield compared with fertilization and control at P = 0.05. Plastic mulching increased pepper yield significantly over that with no mulching at P = 0.05.