During the early 19th century, there was a large population growth caused by the improvements of the agricultural revolution of the 18th century. many historians believe this population increase is due to

increases in labour and land productivity

Explanation:

The period of agricultural revolution which began in 18th century was the time of gradual transformation of the old-fashioned agricultural system. The transformation included the reallocation of lands to different owners so that farms can become more compacts together with other technological improvements from increased investments.

Improved crop yields and enhanced diversity of vegetables and wheat were seen as a result of changes in crop rotation patterns and livestock utilisation. The people in those areas became healthier and better nourished by these changes. The government in Great Britain passed laws that permitted rich lords to buy public-fields and displace smaller farmers. This paved way for the migration of persons seeking wage labour in the municipalities and the workers provided labour for new industries.