The Study of a Yearly Two Cropping System’s Popularizationin Jiangnan of Republic of China

Compared with the middle of the 19th century, the popularization rate of a yearly two cropping system decrease in Jiangnan of Republic of China. Specifically, the dominant crop cultivation system in cotton and rice area are three cropping within two years and four cropping within three years, a yearly cropping and a yearly two cropping in sericulture and rice area, a yearly cropping in rice area. The direct reason for this is the fertilizer input reduction and the substantial population loss post-war of the Taiping Heavenly Kingdom