Cause to vanish, overwhelm, as in The independent bookstores are being plowed under by the large chains. This term alludes to the farmer's burying vegetation by turning it into the soil with a plow. [Second half of 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use plow under in a sentence
Green crops, to plow under, are in many places largely raised, and are always beneficial.The Elements of Agriculture | George E. Waring
It makes a good growth during the fall and early winter and is in blossom and ready to cut or plow under in April or May.The First Book of Farming | Charles L. Goodrich
The cotton is grown for market, the corn partly to sell, partly to feed, the oats to feed and the cowpeas to plow under.The First Book of Farming | Charles L. Goodrich
In the spring plow it under, and you plow under all the nitrogen that the plants had collected the previous year.
You don't get quite the same benefit from the green manure when you pasture as when you plow under.