EFFECTS OF NITROGEN RATES AND FREQUENCY OF APPLICATION ON COFFEE YIELD AND QUALITY IN KENYA

There was positive clean coffee yield response to fertilizer applications. Although there was no consistent significant differences between the nitrogen rates, timing of application and their interactions, the lower rate of 50 kg N/ha applied four times a year in March, May, October and December gave the highest positive response. High frequencies of applications were observed to be more effective at lower rates of applied nitrogen but the effect diminished as the rates were raised. However, at very high rates of application, the high frequency of applications were also noted to give higher responses than the lower number of applications.

A general increase in large sized beans (% grade 'A' sized coffee beans) with fertilizer applications was observed. Where fertilizer was split into four applications a year, higher proportion of the percent grade 'A' sized beans were recorded.