Between the 17th century and the mid-19th century, Britain saw a large increase in agricultural productivity and net output. New agricultural practices like enclosure, mechanization, four-field crop rotation to maintain soil nutrients, and selective breeding enabled an unprecedented population growth to 5.7 million in 1750, freeing up a significant percentage of the workforce, and thereby helped drive the Industrial Revolution. The productivity of wheat went up from 19 US bushels (670 l; 150 US dry gal; 150 imp gal) per acre in 1720 to around 30 US bushels (1,100 l; 240 US dry gal; 230 imp gal) by 1840, marking a major turning point in history.[145]