The ancient farm was a frugal place where farmers and their families tried to make use of everything. Grain served for food. The straw from wheat and barley was collected for animal food or for brick-making. Even manure was useful as fertilizer in fields. That said, when the psalmist wanted to describe the wicked, he seized on the one useless thing. Chaff was so useless that the wind was allowed to sweep it away.
On the other hand, the psalmist describes the righteous not just as useful, but as pleasurable. Unlike the grains and legumes, the fruit tree was not necessary for survival. Not only that, but a fruit tree growing by a stream didn't cause extra work for the farmer. For the keeper of an orchard, it would surely be a different story. But in this case, and for the purpose of this metaphor, the tree didn't need irrigation or human toil. All it brought was the joy of eating luscious fruit.
God who makes the fruit and the grain to grow, remind us always that you take pleasure in the world. As we go about our daily lives, help us to see the things that cause you to look at creation and call it good. Amen.
Psalm 1 (NRSV)
1 Happy are those who do not follow the advice of the wicked, or take the path that sinners tread, or sit in the seat of scoffers;
2 but their delight is in the law of the Lord, and on his law they meditate day and night.
3 They are like trees planted by streams of water, which yield their fruit in its season, and their leaves do not wither. In all that they do, they prosper.
4 The wicked are not so, but are like chaff that the wind drives away.
5 Therefore the wicked will not stand in the judgment, nor sinners in the congregation of the righteous;
6 for the Lord watches over the way of the righteous, but the way of the wicked will perish.