Temporal changes in soil organic carbon contents and δ <sup>13</sup>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. (2012). Temporal changes in soil organic carbon contents and δ <sup>13</sup>C values under long-term maize-wheat rotation systems with various soil and climate conditions, 183-184 67-73. http://dx.doi.org/10.1016/j.geoderma.2012.03.003
Understanding soil organic carbon (SOC) decomposition and its replenishment by contrasting plant residues is critical to rationally manage soil carbon pools. Long-term (15years) 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 δ 13C values. In the non-fertilized Control treatments mean annual C inputs (mainly roots) at the various sites ranged from 0.39 to 1.24Mgha -1, and SOC contents remained largely unchanged during the 15years study. However, results for the fertilized treatments indicated that SOC concentration increased by 1gkg -1 for every 24.3 (5.4-45.2) MgCha -1 from roots alone in the NPK treatment and for every 29.4 (11.1-52.6) MgCha -1 from crop roots plus straws in the NPKSt treatment. Furthermore, there was a positive correlation among changes in SOC, C 4-derived C and C 3-derived C and the δ 13C values in all treatments across the four sites. Our results suggest that the δ 13C value was a useful tool to quantify temporal changes of SOC from C 4 and C 3 plants, even when actual changes in soil C stock were small in these wheat-maize rotation cropping systems. © 2012.
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