Fertilizer nitrogen in fertigated coffee crop: Absorption changes in plant compartments over time

Nitrogen (N) dynamics in plants during their development in agricultural crops has to be well understood in order to design management practices that lead to maximum productivity with minimum N loss from the system. In a labeled fertilizer field study 15N accumulation in different plant parts of mature coffee was observed over time. The objective was to ascertain the time of greatest crop N demand as a scientific basis for designing fertigation schedules. Coffee plantations of central Brazil are routinely fertigated only with extremely high applications of N. Good coffee bean production should be sustainable by applying lower N quantities at those frequencies designated by additional scientific criteria. The experiment was carried out over a complete coffee cropping cycle (2008/2009) in a field of low soil fertility in the Brazilian savanna “cerrado”. Rates of 0, 200, 400, 600 and 800 kg N ha−1 year−1 as 15N-labeled urea were applied via fertigation, divided equally over the year into 26 portions, distributed every 14 days. Changes of N absorption in various plant compartments indicated that fertilizer use could be improved if a lower rate is applied only up to the beginning of fruit maturation, focusing on the stage before fruit filling. This specific stage was found to be the period of greatest N consumption by leaf and fruit. 15N absorption data showed that it is possible to decrease the routine fertilization rate of 600 to a much lower value, of order of 200 kg N ha−1 without decreasing the production of coffee beans.

► Changes in fertigated coffee crop nutrient uptake related to rates.
► The highest nitrogen demand occurs during grain filling.
► Nitrogen application thus must be highest prior this period.