(Air) humidity

The plant must always be dry when administering granular fertilizers and liquid fertilizers. So please wait a few hours before spreading after it has rained. Spreading/spraying fertilizers can cause leaf burn. The image shows leaf burn caused by spraying urea.

The fertilizer becomes sticky when you spread fertilizer with high humidity or during (light) rain. This can cause clod formation, resulting in blockages in the spreader. This can have a significant influence on the spreading pattern. Therefore, ensure the fertilizer spreader is covered with tarpaulin when high humidity.
Prilled fertilizers, in particular, are sensitive to humidity during storage and handling. The grains stick together at high humidity, with a high chance of cloud formation. When applying liquid fertilizers, the crop must be dry.

Bemesting, 2013.
Bouma, Agrometeorologisch specialist bij Agrometeorologisch Adviesbureau Erno Bouma, 2014.