Assertion: urea's use | /r/HasProperty | envisaged
Facets:
value: during the 1950s
type: TEMPORAL
value: during 1960s
type: TEMPORAL
value: because of its high nitrogen content
type: CAUSE
Source sentences:
text: The use of melamine as fertilizer for crops had been envisaged during the 1950s and 1960s because of its high nitrogen content (2/3).