Characteristics of soil organic carbon components and their relationship with tobacco chemical components in Liangshan tobacco-planting areas

To investigate the relationship between the characteristics of soil organic carbon components and the quality of tobacco leaves, the samples of soils and tobacco leaves were collected from 10 tobacco-planting areas in Liangshan and analyzed. The results showed that:1) The contents of total soil organic carbon and high, medium and low active organic carbon in Liangshan tobacco-planting areas were 2.24-27.84, 0.16-1.43, 0.51-3.46 and 0.65-4.64 g·kg^-1, respectively. The carbon/nitrogen ratio in soils ranged from 2.52 to 23.75 with a large variation. 2) The contents of total soil organic carbon and high, medium and low active organic carbon extremely significantly positively correlated to the contents of alkaline nitrogen, available phosphorus, available potassium and total nitrogen, which indicated that soil organic carbon was an important indicator for soil fertility. 3) When organic carbon contents in soils were higher, the proportion of tobacco samples with higher total alkaloid and total nitrogen contents increased significantly. When soil carbon/nitrogen ratio was lower, the proportion of tobacco samples with higher total alkaloid content decreased remarkably, which suggested that soil organic carbon had important effects on the contents of total alkaloid and total nitrogen in tobacco leaves.