Leaching is the dominant route for soil organic carbon lateral transport under crop straw addition on sloping croplands
2018
Keke, Hua | Bo, Zhu
Few field data sets are available that systematically measure soil organic carbon (SOC) transport via surface runoff, leaching and soil erosion under crop straw applications. Therefore, organic carbon (C) loss fluxes via the three routes were simultaneously observed from 2010 to 2012 based on a crop straw addition experiment. This study included three treatments: CK (no fertilizer); RSD (crop straw addition) and RSDNPK (crop straw addition combined with mineral fertilizers). As compared with CK treatment, annual dissolved organic C (DOC) loss caused by surface runoff under RSD and RSDNPK treatments decreased significantly (P < 0.05) by 302.8% and 294.2%. Similarly, corresponding organic C loss caused by soil erosion reduced sharply by 638.8% and 1227.3%. In contrast, corresponding annual DOC leaching fluxes increased significantly (P < 0.05) by 133.3% and 109.3%. Overall, the total fluxes of SOC transport under RSD and RSDNPK treatments decreased significantly (P < 0.05) by 132.3% and 184.1% compared with CK treatment (4975.7 ± 1207.8 mg/m<sup>2</sup>). DOC leaching accounted for 70% and 77% of SOC transport under RSD and RSDNPK treatments. These results clearly show that leaching is the dominant route of SOC lateral transport under crop straw applications. Therefore, reduced DOC leaching is the crucial link to enhance SOC sequestration when crop straw is returned to sloping croplands.
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