Concise Bible Dictionary:
Spring Farm Work – Grafting – [from a drawing by Winslow Homer]
The reference to the grafting of trees in Romans 11 shows that the system was then practiced. It speaks of Gentiles, the wild olive branches, being grafted into the good olive tree; and this is said to be “contrary to nature.” Gentiles have now been grafted into the tree of witness on earth, and of promise; but by-and-by the natural branches, Israel, will again be grafted into “their own olive tree.” It does not refer to individual salvation (Rom. 11:17-24).