Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study
Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study
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DOI：
10.1007/s11104-012-1363-8
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发表时间：
2013-03
期刊：
影响因子：
4.9
通讯作者：
J. Pausch;Jing Tian;M. Riederer;Y. Kuzyakov
中科院分区：
文献类型：
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作者：
J. Pausch;Jing Tian;M. Riederer;Y. Kuzyakov
背景和目的植物根部沉积是碳(C)循环中最不确定的组成部分。根据现有的方法，根沉降量只能粗略地估计，因为与其他有机碳库相比，根沉降量在土壤中的持久性很短。我们提出了一种在田间尺度上通过假定根沉积-C与根-C的比率恒定来量化根沉积的方法。方法在控制的条件下用14CO2脉冲标记玉米植株，并将土壤14CO_2排出的土壤分离为根和根瘤微生物呼吸。后者和土壤中残留的~(14)C活性对应于总的根沉降量。通过将根沉积-14C与根-14C相关联，计算出根沉积与根的比值为0.56。结果玉米分配了298万kg/hA−1为根C，166g/hA−1为地下根沉积C，其中50%在10 cm以上得到回收。根据14C数据对根沉降量的去向进行了估算，结果表明，62%的根沉降量在16天内被矿化，7%和0.3%的根沉降量分别被并入微生物生物量和DOC中，31%的根沉降量在土壤中被回收。结论本方法不仅考虑了土壤中残留的根沉降量，还考虑了微生物分解后以CO2形式从土壤中释放出来的根沉降量，从而改进了根沉降量的估算方法。
Background and aimsRhizodeposition of plants is the most uncertain component of the carbon (C) cycle. By existing approaches the amount of rhizodeposition can only roughly be estimated since its persistence in soil is very short compared to other organic C pools. We suggest an approach to quantify rhizodeposition at the field scale by assuming a constant ratio between rhizodeposited-C to root-C.MethodsMaize plants were pulse-labeled with14CO2under controlled conditions and the soil14CO2efflux was separated into root and rhizomicrobial respiration. The latter and the14C activity remaining in the soil corresponded to total rhizodeposition. By relating rhizodeposited-14C to root-14C a rhizodeposition-to-root ratio of 0.56 was calculated. This ratio was applied to the root biomass C measured in the field to estimate rhizodeposition under field conditions.ResultsMaize allocated 298 kg C ha−1as root-C and 166 kg C ha−1as rhizodeposited-C belowground, 50 % of which were recovered in the upper 10 cm. The fate of rhizodeposits was estimated based on the14C data, which showed that 62 % of total rhizodeposition was mineralized within 16 days, 7 % and 0.3 % was incorporated into microbial biomass and DOC, respectively, and 31 % was recovered in the soil.ConclusionsWe conclude that the present approach allows for an improved estimation of total rhizodeposition, since it accounts not only for the fraction of rhizodeposits remaining in soil, but also for that decomposed by microorganisms and released from the soil as CO2.