Because of the shallow-rooted nature of the plant and the significant losses that can occur due to leaching and volatilization, regular N-applications are important. In addition, bananas are also unable to store nitrogen within the pseudostem. Thus, any lack of nitrogen results in slow growth, with the plant 'shutting-down'.
Too much nitrogen however, will 'extend' the bunch, resulting in undesirably large gaps between the hands. In addition, bunches are smaller, do not fill properly, have a reduced green life at harvest and are more prone to dropping from the plant.