Towards constraining the magnitude of global agricultural sediment and soil organic carbon fluxes
Towards constraining the magnitude of global agricultural sediment and soil organic carbon fluxes
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DOI：
10.1002/esp.3198
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发表时间：
2012-05-01
影响因子：
3.3
通讯作者：
Six, Johan
中科院分区：
文献类型：
--
作者：
Doetterl, Sebastian;van Oost, Kristof;Six, Johan
需要关于土壤侵蚀程度和速度的可靠定量数据，以了解土壤侵蚀引起的碳交换的全球意义，并支持制定以科学为基础的减缓战略，但仍然存在很大的不确定性。农业土壤和土壤有机碳（SOC）侵蚀的现有估计是非常不同的，跨越两个数量级。本研究的主要目的是测试现有评估的基础假设，并减少与农业土壤和SOC侵蚀的全球估计相关的不确定性。我们参数化了一个简化的侵蚀模型驱动的粗糙的全球数据库使用的经验数据库，涵盖了毗连的美国。我们的模型结果和经验估计之间的良好的协议表明，这里提出的方法抓住了大陆尺度的农业侵蚀的本质，它可以用来预测侵蚀的全球碳循环的意义及其对土壤功能的影响。我们得到的全球土壤侵蚀率为10.5？农田为1.7毫克公顷-1年-1，牧场用毫克公顷-1年-1。这相当于SOC侵蚀率为193？kg C ha ~（-1）y ~（-1），农田为40.4？kg C ha-1 y-1用于侵蚀牧场，导致土壤的全球通量为20.5（+/- 10.3）Pg y-1，403.5（+/- 201.8）Tg C y-1。虽然很难准确评估与我们对全球农业侵蚀的估计相关的不确定性，主要是由于缺乏（亚）热带地区的模型测试，但我们的估计值明显低于以前基于地块实验外推或全球应用侵蚀模型的评估。我们的方法有可能在大陆和全球尺度上量化侵蚀引起的干扰的速率和空间特征：通过将我们的模型与全球土壤剖面数据库联系起来，我们估计了农业引起的土壤剖面变化。这表明，侵蚀引起的表层土壤有机碳含量的变化是显着的，在全球范围内（平均22%，在50？因此，农业土壤应被视为可以迅速变化的动态系统。版权所有（C）2011约翰威利父子有限公司
Reliable quantitative data on the extent and rates of soil erosion are needed to understand the global significance of soil-erosion induced carbon exchange and to underpin the development of science-based mitigation strategies, but large uncertainties remain. Existing estimates of agricultural soil and soil organic carbon (SOC) erosion are very divergent and span two orders of magnitude. The main objective of this study was to test the assumptions underlying existing assessments and to reduce the uncertainty associated with global estimates of agricultural soil and SOC erosion. We parameterized a simplified erosion model driven by coarse global databases using an empirical database that covers the conterminous USA. The good agreement between our model results and empirical estimates indicate that the approach presented here captures the essence of agricultural erosion at the scales of continents and that it may be used to predict the significance of erosion for the global carbon cycle and its impact on soil functions. We obtained a global soil erosion rate of 10.5?Mg ha-1 y-1 for cropland and 1.7?Mg ha-1 y-1 for pastures. This corresponds to SOC erosion rates of 193?kg C ha-1 y-1 for cropland and 40.4?kg C ha-1 y-1 for eroding pastures and results in a global flux of 20.5 (+/- 10.3) Pg y-1 of soil and 403.5 (+/- 201.8) Tg C y-1. Although it is difficult to accurately assess the uncertainty associated with our estimates of global agricultural erosion, mainly due to the lack of model testing in (sub-)tropical regions, our estimates are significantly lower than former assessments based on the extrapolation of plot experiments or global application of erosion models. Our approach has the potential to quantify the rate and spatial signature of the erosion-induced disturbance at continental and global scales: by linking our model with a global soil profile database, we estimated soil profile modifications induced by agriculture. This showed that erosion-induced changes in topsoil SOC content are significant at a global scale (an average SOC loss of 22% in 50?years) and agricultural soils should therefore be considered as dynamic systems that can change rapidly. Copyright (C) 2011 John Wiley & Sons, Ltd.