Effects of straw returning on carbon pool in loess-cinnamon soil and economic characteristics of tobacco leaves in Luoyang tobacco-growing areas

To investigate the effects of decomposed straw returning on the carbon pool in tobacco-growing soils and the yield and quality of flue-cured tobacco, a field experiment was conducted in Ruyang County, Luoyang City, Henan Province in 2017. On the basis of conventional fertilization, the amounts of decomposed wheat straw for returning to field were set at 0, 6 000, 9 000 and 12 000 kg/hm². The soil carbon pool indexes (total organic carbon, active organic carbon, microbial biomass carbon and microbial biomass nitrogen) of soil samples were determined. The results showed that straw returning significantly increased the contents of total organic carbon, microbial biomass carbon, microbial biomass nitrogen and soluble organic carbon and raised the activity index and management index of high active, medium active and active carbon pools and the yield and output value of tobacco leaves. Conventional fertilization combined with 12 000 kg/hm² decomposed wheat straw had better effects on loess-cinnamon soils of Luoyang tobacco-growing areas.