What does the following line from "Grass" by Carl Sandburg mean: "I am the grass; I cover all"?

Carl Sandburg's "Grass" is a short but powerful poem which utilizes the imagery of grass covering the dead of famous battles to represent the passage of time leading to healing or, arguably, forgetting. Speaking in the voice of personified grass, the speaker declares that he will "cover all," a statement which evokes the image of grass slowly springing up out of the dirt mounds of graves as time passes. The idea of something green emerging out of the carnage left behind after battles like Gettysburg, Ypres, and Verdun seems to represent the return of spring to a world harrowed by war: despite the horror of these events, things will still be born, and the grass will be fed on the bodies of those who have been killed. Their death, in a way, contributes to rebirth as symbolized by the green grass covering the graves. Grass, like time, erases the wounds made by war—but there is also an element of warning in the poem, as we hear passengers ask, "What place is this?" Once grass has covered the battlefields, it can certainly indicate that things have begun to heal, but it can also signify that the dead, and the causes of their deaths, have been forgotten.