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Título

COFFEE RESPONSE TO NITROGEN FERTILIZATION IN BRAZIL – A REVIEW

Resumo

Nitrogen (N) rates applied to coffee are usually 300 kg N ha-1 or higher. Rates are based on expected yields, leaf N concentration, and experimental data from field studies. This work is an analysis of six experiments with N fertilization from 1970 to 2010 with at least four consecutive harvests (mean: 6.1 harvests). The surveys involved responses to N rates and sources, totaling 69 treatments and 428 yield observations. The information was initially consolidated into 15 normalized N response curves and then into a single mean response curve. We calculated the N rates for maximum grain yield, the partial productivity factor (PPF), the percentage of applied N exported at harvest (N export), the difference between applied N and exported N (N Surplus), and the economic return of N fertilization. The original data showed great variation; rates for maximum yield ranged from 255 to 730 kg N ha-1, resulting in coffee yields of 1 814 to 5241 kg ha-1. On average, the N rate for a maximum response was 378 kg N ha-1, corresponding to a yield of 2903 kg ha-1. The PPF ranged from 5.0 to 20.0 (mean of 11.0) kg grains kg-1 fertilizer N. The percentage of applied N exported (grains + husk) ranged from 16 to 87% (average 37%). The mean N surplus was 189 kg ha-1 (ranging from 14 to 387 kg ha-1 for N rates 100 and 500 kg N ha-1, respectively). For the average prices from 2016 to 2019, the N rate for maximum economic return was 378 kg ha-1. Simulating nitrogen fertilizer prices 50% higher than the average for the period and coffee prices 54% lower, the rate for maximum return was 309 kg N ha-1. In the scenario stressed by high oil prices in 2022, the N rate for maximum return was 358 kg N ha-1. It is concluded that, despite the low N use efficiency in coffee, the rates for maximum economic return are resiliently high because of the large crop response to N and the high coffee prices, which stimulates farmers to continue to apply high rates of this nutrient.

Palavras-chave

Coffea arabica; N fertilization; N use efficiency; economic return.