Carbon dynamics of surface residue- and root-derived organic matter under simulated no-till
Carbon dynamics of surface residue- and root-derived organic matter under simulated no-till
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DOI：
10.2136/sssaj2000.641190x
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发表时间：
2000-01-01
影响因子：
2.9
通讯作者：
Cambardella, CA
中科院分区：
文献类型：
--
作者：
Gale, WJ;Cambardella, CA
免耕措施有增加土壤有机碳的潜力，但对地表残留物和根系对土壤有机碳积累的相对贡献知之甚少。在模拟的免耕试验中，我们研究了C-14标记的地表残留物和原位根在1年培养期间的去向。在培养过程中收集的土壤样本被化学分散，并被分成五个颗粒大小和密度组分。测定了各组分的有机碳、碳14和总氮含量，并用碱捕捉法测定了14C在呼吸作用中的损失。360d后，第0d地表残留物中66%的C-14以(CO2)-C-14的形式呼吸，11%残留在土壤表面，16%留在土壤中。相比之下，土壤中56%的根源C-14以(CO2)-C-14的形式演化，42%的C-14残留在土壤中。大(500-2000微米)和小(53-500微米)颗粒有机质(POM)组分总共含有土壤中最初根源C-14的11%到16%，相比之下，POM只含有初始表面残留物C14的1%到3%。这些数据显示了分解过程中地表残留物和根源C在分配上的明显差异，暗示了免耕对土壤有机C积累的有利影响主要是由于增加了根源C在土壤中的滞留。
No-till practices have the potential to increase soil organic C, but little is known about the relative contribution of surface residue and roots to soil organic C accumulation, In a simulated no-till experiment, we studied the fate of C-14-labeled surface residue and in situ roots during a 1-yr incubation. Soil samples collected during the incubation were chemically dispersed and separated into five particle size and density fractions. The organic C, C-14, and total N content of each fraction was determined, Alkali traps were used to measure (14C) losses due to respiration. After 360 d, 66% of the C-14 contained in the surface residue on Day 0 had been respired as (CO2)-C-14, 11% remained in residue on the soil surface, and 16% was in the soil. In comparison, 56% of the root-derived C-14 in the soil was evolved as (CO2)-C-14 and 42% remained in the soil. The large (500-2000 mu m) and small (53-500 mu m) particulate organic matter (POM) fractions together contained 11 to 16% of the initial root-derived C-14 in the soil, In contrast, POM contained only 1 to 3% of the inital surface residue-derived C-14. These data show clear differences in the partitioning of surface residue- and root-derived C during decomposition and imply that the beneficial effects of no-till on soil organic C accrual are primarily due to the increased retention of root-derived C in the soil.