"O Lord, almighty God, who desist not from pouring out upon men a superabundance of heavenly dew and the substance of earth's richness, we render thanksgiving to Thy most loving Majesty for all Thy gifts. We continue to beseech Thy clemency, that Thou would deign to bless, preserve, and defend from drought and from every injury the harvest of our fields, mercifully sending rain to nourish them. Grant, likewise, that having had our desire for earthly needs filled, we may bask under Thy protection, praise Thy goodness and mercy without ceasing, and make use of temporal goods in such a way as not to lose eternal goods. Through Christ our Lord, amen."
(adapted from Benedictionale, #107, Blessing of granary or harvests (Roman Ritual, Vol III))