Charles Ellicott Commentary Psalms 104:14

"He causeth the grass to grow for the cattle, And herb for the service of man; That he may bring forth food out of the earth," — Psalms 104:14 (ASV)

For the service of man — that is, for his use (so Gesenius). But some deny this meaning to the Hebrew, which properly means “labour” or “office.” (In 1 Chronicles 27:26; Nehemiah 10:37, it means “agriculture,” “tillage.”) Hence they render, “And herbs for man’s labour in bringing them forth from the earth,” alluding to his task of cultivating the soil. Standing by itself the clause would indeed naturally require this sense, but the parallelism is against it, and in 1 Chronicles 26:30, service of a king, we have a near approach to the meaning “use.”

That he may. — Better, bringing food out of the earth, taking the verb as gerund instead of infinitive absolute.