Vertical distribution and storage of soil organic carbon under long-term fertilization

To determine the effect of different fertilization schemes on soil organic carbon content and storage, long-term fertilization experiment were carried out in Nanhu Experimental Station, Hubei Academy of Agricultural Sciences. With the exception of single application of nitrogen or manure, soil organic carbon content and storage in the 0~20 cm soil layer increase under fertilization compared to the control. Soil organic carbon content and storage in the 0~20 cm and 0~100 cm soil layers increase under combined application of chemical fertilizer and manure compared to the control and single application of chemical fertilizer or manure. Soil organic carbon content is less affected and storage is lower with single chemical fertilizer or single manure application in all the soil layers. However, soil organic carbon content and storage in the 0~20 cm and 20~40 cm soil layers are higher under combined application of chemical fertilizer and manure. Except for the control and combined application of chemical fertilizer and excessive manure, significant positive correlations (P<0.05) are noted between soil total nitrogen and organic carbon content under other fertilization schemes. In conclusion, combined applications of chemical fertilizer and manure should be advocated to enhance agricultural soil organic carbon storage.