Changes of Nutritional Status during a Phenological Cycle of Coffee under High Nitrogen Supply by Fertigation

High-technology coffee cultivation systems involving fertigation commonly apply high rates of nitrogen (N). However, there is little information on the plants' uptake of N under these conditions. The objective of this study was to evaluate the changes in the nutritional status of coffee plants during a phenological cycle in response to N applied by fertigation. The study was conducted with 7-year-old trees of Coffea arabica L., under pivot irrigation and fertigation, with five N rates (0, 200, 400, 600, and 800 kg ha-1) applied on the plants. The changes in nutritional status were monitored during the phenological cycle, and the yield was measured at the end of the cycle. The N concentration increased with the N rates and varied with the phenological period, with the greatest concentration occurring during anthesis, the same as for the sulfur level. However, N rate did not affect the concentrations of other nutrients. The greatest concentrations of phosphorus, calcium, and magnesium were obtained in the final fructification phases and for potassium in the initial phases. Micronutrient concentrations were greater in the vegetative phases and anthesis but were reduced in the fruit- formation phase and increased again when the berries started to mature. The maximum yield, considering a relative production of 90%, was obtained with application of 415 kg ha-1 of N. Leaf concentrations of N were directly related to the N rates, showing that the nutritional status of coffee plants can be evaluated in the ripening phase to adjust the fertilization parameters for the next year.