Temporal changes in soil organic carbon contents and delta13 C values under long-term maize-wheat rotation systems with various soil and climate conditions

Tang, X.; Ellert, B.H.; Hao, X.; Ma, Y.; Nakonechny, E.; Li, J.

Geoderma 183-184


ISSN/ISBN: 0016-7061
Accession: 037170902

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Understanding soil organic carbon (SOC) decomposition and its replenishment by contrasting plant residues is critical to rationally manage soil carbon pools. Long-term (15 years) field experiments in maize-wheat (Zea mays L.-Triticum aestivum L.) rotation systems at diverse sites with contrasting climates and soil properties were conducted to evaluate the temporal dynamics of the C inputs, SOC concentrations and delta13 C values. In the non-fertilized Control treatments mean annual C inputs (mainly roots) at the various sites ranged from 0.39 to 1.24 Mg ha(-1) , and SOC contents remained largely unchanged during the 15 years study. However, results for the fertilized treatments indicated that SOC concentration increased by 1 g kg(-1) for every 24.3 (5.4-45.2) Mg C ha(-1) from roots alone in the NPK treatment and for every 29.4 (11.1-52.6) Mg C ha(-1) from crop roots plus straws in the NPKSt treatment. Furthermore, there was a positive correlation among changes in SOC, C4 -derived C and C3 -derived C and the delta13 C values in all treatments across the four sites. Our results suggest that the delta13 C value was a useful tool to quantify temporal changes of SOC from C4 and C3 plants, even when actual changes in soil C stock were small in these wheat-maize rotation cropping systems.