Mid 19th century; earliest use found in Edward Bulwer-Lytton (1803–1873), writer and politician. From agronomy + -al, perhaps after formations in -nomial.
Definition of agronomial in US English:
agronomial
adjectiveˌaɡrəˈnəʊmɪəl
Agronomic.
Origin
Mid 19th century; earliest use found in Edward Bulwer-Lytton (1803–1873), writer and politician. From agronomy + -al, perhaps after formations in -nomial.