Row and industrial crops were more remunerative than grain, or at worst provided their cultivators with extra income or consumables (hence they were called `cash crops'). Their cultivation spread steadily during the late 19th and earlier 20th centuries, and they were increasingly grown as part of improved crop rotations (see below). Flax and potatoes were grown in the west, north-west, Central Industrial Region and the Urals; sugar-beet in northern Ukraine and Central Agricultural region; sunflower in south-eastern Russia and southern Ukraine; cotton in central Asia and Transcaucasia. By 1917 most vegetables and industrial crops were grown by the peasants. By this time sugar-beet was the only culture to be grown mainly on large estates (and this too largely fell into peasant hands as a result of the Revolution). These cultures require much more work than grain (hence called `intensive cultures'). Before the mechanization of agriculture potatoes needed 64 man-days of labour a year per "desyatin" (1 "desyatin" is about 1.1 hectare), flax or cotton up to 110 man-days, sugar-beet as much as 180. This compared with only 30 and 23 man-days a year for winter and spring grain respectively.