Cotton growing is highly mechanized. To plant the crop, a tractor pulls a planter. On the planter, metal discs under the seed boxes open the ground in rows called furrows. Seeds and a small amount of fertilizer are dropped into the new furrow and are then covered over. Although some cotton fields are still harvested by hand, machines called cotton pickers and cotton stripers do the bulk of the harvesting. The mechanical cotton picker picks the cotton boll from the plant. The mechanical cotton stripper strips the boll and often the leaves from the plant. A stripper can harvest about 500 pounds (227kg) of cotton an hour. By comparison, it would take one man 33 hours to harvest the same amount. Over the last 20 years, both cotton yields and number of acres used for cotton farming have increased. Click on PICTURES below to see a cotton combine. Click on CHARTS below for additional facts about cotton.