Priming effect and C storage in semi-arid no-till spring crop rotations
Priming effect and C storage in semi-arid no-till spring crop rotations
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DOI：
10.1007/s00374-003-0587-4
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发表时间：
2003-04-01
影响因子：
6.5
通讯作者：
Bolton, H
中科院分区：
文献类型：
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作者：
Bell, JM;Smith, JL;Bolton, H
采用免耕（NT）和连作等侵入性较小的管理措施，可以通过保留土壤有机质（SOM）来减少农业土壤的二氧化碳排放。我们假设碳储存随着耕作强度的增加和耕作的减少而增加。我们还假设脉冲添加 C 会增加天然 SOM 的矿化。我们评估了四种轮作土壤中 0 至 5 厘米深度的碳储存：冬小麦-休耕、春小麦-化学休耕、连续硬红春小麦和春小麦-Ritzville 粉质壤土（Calcidic Haploxeroll）上的春大麦。在两项使用 C-14 标记的麦秆的孵化研究中，我们追踪了添加残留物的分解情况，该分解受到 (1) 耕作频率、(2) 耕作的影响。 (3)脉冲式添加C。在整个培养过程中的任何时间，四轮旋转之间不存在C-14矿化的差异。然而，小麦连续轮作和休耕轮作之间总二氧化碳产量的差异表明天然 SOM 的启动，其程度似乎与真菌和细菌对添加残留物分解的相对贡献有关。在第二次孵育中向选定的样品中添加未标记的麦秆会导致在对照中未见的 C-14-CO2 冲刷。这种启动效应表明，与干扰相比，碳输入对残留碳的矿化有更大的影响，内源代谢似乎是启动碳的来源。随着土壤中真菌：细菌比例的增加，启动变得更加明显。
Adoption of less invasive management practices, such as no-till (NT) and continuous cropping, could reduce CO2 emissions from agricultural soils by retaining soil organic matter (SOM). We hypothesized that C storage increases as cropping intensity increases and tillage decreases. We also hypothesized that pulsed addition of C increases the mineralization of native SOM. We evaluated C storage at the 0- to 5-cm depth in soils from four crop rotations: winter wheat-fallow, spring wheat-chemical fallow, continuous hard red spring wheat, and spring wheat-spring barley on a Ritzville silt loam (Calcidic Haploxeroll). In two incubation studies using C-14-labeled wheat straw, we traced the decomposition of added residue as influenced by (1) cropping frequency, (2) tillage. and (3) pulsed additions of C. Differences in C-14 mineralization did not exist among the four rotations at any time throughout the incubations. However, differences in total CO2 production between the continuous wheat rotations and the fallow rotations point to a priming of native SOM, the degree of which appears to be related to the relative contributions of fungi and bacteria to the decomposition of added residue. Addition of non-labeled wheat straw to select samples in the second incubation resulted in a flush of C-14-CO2 not seen in the controls. This priming effect suggests C inputs have a greater effect on mineralization of residual C compared to disturbance and endogenous metabolism appears to be the source of primed C. with priming becoming more pronounced as the fungal: bacterial ratio in the soil increases.