A recent Intergovernmental Panel on Climate Change (IPPC) report concludes that global warming, while already a global crisis, is likely to become even more devastating. The scientific consensus is that global warming is caused by increases in greenhouse gases including carbon dioxide. The Sahel of West Africa seems to be more adversely affected by such climate changes, leading to reduced and more sporadic rainfall. In addition, food security in the region is tenuous and fragile, due to adverse climate change, but also due to the historical mining of nutrients and carbon. With the adoption of the Kyoto accords, at least by some countries, sequestered carbon (C) has become a tradable commodity. This provides a double incentive to increase soil organic carbon in the C-depleted and degraded soils of West Africa — return C to improve soil quality and assist in removing CO₂ from the atmosphere to assist in mitigating climate change. A challenge, however, remains to determine which agricultural systems can actually sequester C. The technology called Aménagement en courbes de niveau (ACN), which can be roughly translated as ‘Ridge-tillage’, has given crop yield increases of 30 to 50%. To date, there has only been anecdotal evidence suggesting that Aménagement en courbes de niveau leads to increased soil organic C. The objectives of the study reported here were to determine whether the technology has the potential to sequester C in West African soils, and, if so, how much. In this study, soil organic C was measured by combustion methods in soils sampled at 0–20 and 20–40 cm depths in a series of experiments in Mali, Senegal and The Gambia. Soil organic C was measured in three very different types of experiments, all including Aménagement en courbes de niveau technology, resulting in three methods of measuring C sequestration. Our results indicate that the Aménagement en courbes de niveau technology significantly increased maize yields by 24% by weight in the Gambia experiment while soil organic C was increased by 26% in The Gambia, by 12% in Siguidolo, Mali, and by 14% in peanut systems of Nioro, Senegal. These increases in soil organic C are likely due to three factors: (1) reduced erosion and movement of soil, (2) increased crop growth resulting from the greater capture of rainfall, and (3) increased growth and density of shrubs and trees resulting from the increased subsoil water, resulting in turn from the increased capture of rainfall, and reduced runoff. Measuring soil C on fields that were successively placed under Aménagement en courbes de niveau management and the use of replicated experimental plots appear to be the best methods to quantify the C sequestration potential of the practice. These results indicate that this soil and water conservation technology not only harvests water and increases food production, but also increases soil organic carbon. This technology thus is a successful technique to sequester C in soils and if carried out in a large region may both offset CO₂ emissions and help mitigate climate change.

中文翻译：

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Aménagementen Courbes de Niveau隔离西非土壤中的有机碳

政府间气候变化专门委员会（IPPC）的最新报告得出的结论是，全球变暖虽然已经是全球性危机，但可能会变得更具破坏性。科学共识是，全球变暖是由包括二氧化碳在内的温室气体增加引起的。西非的萨赫勒地区似乎受到这种气候变化的不利影响，导致降雨减少和零星分布。此外，由于不利的气候变化，而且由于历史上养分和碳的开采，该地区的粮食安全脆弱而脆弱。随着《京都议定书》的通过，至少在某些国家，隔离碳已经成为一种可交易的商品。₂从大气中协助缓解气候变化。然而，确定哪种农业系统可以真正隔离C仍然是一个挑战。这项称为Aménagementen courbes de niveau（ACN）的技术可以粗略地翻译为“ Ridge-tillage”，使作物单产提高了30％至50％ 。迄今为止，只有轶事证据表明尼维乌河上的Aménagementen courbes de niveau导致土壤有机碳增加。此处报道的研究目标是确定该技术是否有潜力隔离西非土壤中的C，如果有的话，还可以隔离多少C。在本研究中，在马里，塞内加尔和冈比亚进行的一系列实验中，通过燃烧方法在0–20和20–40 cm深度采样的土壤中测量了土壤有机碳。土壤有机碳是通过三种非常不同类型的实验进行测量的，包括Aménagementen courbes de niveau技术，这些实验产生了三种测量碳固存的方法。我们的研究结果表明，尼维乌古城这项技术在冈比亚的实验中显着提高了24％的玉米产量，而冈比亚的土壤有机碳增加了26％，马里的Siguidolo增加了12％，塞内加尔的Nioro的花生系统增加了14％。土壤有机碳的增加可能归因于以下三个因素：（1）减少的土壤侵蚀和土壤运动；（2）由于降雨的更多捕获而增加了作物的生长；（3）灌木和树木的生长和密度增加了地下土壤水的增加导致了降雨的增加，进而减少了径流。在连续放置在Aménagementen courbes de niveau下的田地上测量土壤C管理和使用重复的实验区似乎是量化该实践中C隔离潜力的最佳方法。这些结果表明，这种水土保持技术不仅可以收获水和增加粮食产量，而且还可以增加土壤有机碳。因此，该技术是一种将C螯合在土壤中的成功技术，如果在大范围内进行，则既可以抵消CO _2的排放，又可以缓解气候变化。