Walk through Amos, verse by verse, with the great Bible Commentaries of Matthew Henry (1662 - 1714) & Adam Clarke (1760 - 1832)
9:13
Behold, the days come, saith the LORD, that the plowman shall overtake the reaper, and the treader of grapes him that soweth seed; and the mountains shall drop sweet wine, and all the hills shall melt. KJV
{Lo! days come, saith the Lord, and the earer shall (over)take the reaper (Lo! days shall come, and the plowman shall overtake the harvester), and the treader, or (the) stamper, of grape(s) shall (over)take the man sowing seed; and mountains shall drop sweetness, and all small hills shall be tilled.} Wycliffe's Bible
The ploughman shall overtake the reaper - All the seasons shall succeed in due and natural order: but the crops shall be so copious in the fields and in the vineyards, that a long time shall be employed in gathering and disposing of them; so that the seasons of ploughing, sowing, gathering the grapes, treading the wine-press, etc., shall press on the heels of each other; so vast will be the abundance, and so long the time necessary to gather and cure the grain and fruits. We are informed by travelers in the Holy Land, Barbary, etc., that the vintage at Aleppo lasts from the fifteenth of September to the middle of November; and that the sowing season begins at the close of October, and lasts through all November. Here, then, the ploughman, sower, grape-gatherer, and operator at the wine-press, not only succeed each other, but have parts of these operations going on at the same time. But great fertility in the land, abundance in the crops, and regularity of the seasons, seem to be the things which the prophet especially predicts. These are all poetical and prophetical images, by which happy times are pointed out.