And it shall be, when you come into the land...you shall take of the first of all the fruit of the earth, which you shall bring of your land that the L-rd your G-d gives you (Deut. 26:1-2)
One of the reasons for the mitzva of bikurim, first fruits, is that bringing the first of the land's produce to the Holy Temple negates the mistaken notion that the fruits are the result of the farmer's efforts and agricultural acumen. The mitzva reminds him that all of the earth's bounty is ultimately dependent on G-d's blessing, and nothing else. (Akeidat Yitzchak)
All these blessings shall come on you, and overtake you (Deut. 28:2)
What does it mean that the blessings will "overtake you"? That they will come to you in the same place you were before: i.e., that you will not wander astray, off the path of Torah and mitzvot, in your pursuit of wealth and success. (Chashva Letova)