Distribution of soil organic carbon and total nitrogen of the cultivated layer under different tillage practices

To evaluate the carbon and nitrogen sequestration capacity of different tillage practices, soil organic carbon and nitrogen concentrations and storages of the cultivated layer under different tillage practices (conventional tillage, no-tillage and fallow) were compared. The results showed that soil organic carbon under different tillage practices were significantly different among different soil depths and 0 – 5 cm > 5 – 15 cm > 15 – 30 cm (except for the conventional tillage in booting stage). The concentration of soil organic carbon in notillage was higher than that in conventional tillage and fallow. The concentrations of soil total nitrogen were significantly different among different treatments in 5 – 15 cm of jointing stage and 0 – 5 cm of booting and ripening stage, and no-tillage > conventional tillage > fallow. Soil organic carbon storage in the cultivated layer (0 – 30 cm) was increased by no-tillage practice, but soil nitrogen storage was not affected significantly by tillage practices. Soil organic carbon and total nitrogen were negatively correlated with pH, exchangeable K
⁺
and Ca
²⁺
.