Thou shalt take of the first of all the fruit, etc. - This was intended to keep them in continual remembrance of the kindness of God, in preserving them through so many difficulties and literally fulfilling the promises he had made to them. God being the author of all their blessings, the first-fruits of the land were consecrated to him, as the author of every good and perfect gift.
On the subject of firstfruits see the notes at Leviticus 23:9 ff. The firstfruits here in question are to be distinguished alike from those offered in acknowledgment of the blessings of harvest (compare Exodus 22:29) at the Feasts of Passover and Pentecost, and also from the offerings prescribed in Numbers 18:8 ff. The latter consisted of preparations from the produce of the earth, such as oil, flour, wine, etc.; while those here meant are the raw produce: the former were national and public offerings, those of this chapter were private and personal. The whole of the firstfruits belonged to the officiating priest.