Effects of long-term fertiliser regime on soil organic carbon and its labile fractions under double cropping rice system of southern China

ABSTRACT

This study was designed to explore changes in soil bulk density, soil organic carbon content, soil organic carbon stock and soil labile organic carbon fractions under 34 years fertilizer regime in the double-cropping rice system of southern China. The experiment including five fertilizer treatments: chemical fertilizer alone (MF), rice straw residue and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (LOM), 60% organic manure and 40% chemical fertilizer (HOM), and without fertilizer input as control (CK). The results showed that soil bulk density in the 0-20 cm soil layer with long-term fertilizer treatments were significantly decreased compared to CK treatment. The soil organic carbon content and stock with RF, LOM and HOM treatments were significantly higher than that of MF and CK treatments. These results confirmed by the soil carbon management index which were significantly increased with RF, LOM and HOM treatments. As a result, combined application of organic manure with chemical fertilizer is a benefit nutrient management for improving soil organic carbon content and stock, soil carbon management index in paddy field of southern China.