Burial of organic matter for carbon sequestration: Potentials, processes and long-term effects

增加土壤中的碳固存被认为是减少大气中二氧化碳的气候缓解措施。到目前为止，研究和实践主要集中在免耕和免耕对土壤碳储量的影响很小。有机质埋藏提高农业和林业碳储量的选择迄今为止被忽视，几乎没有研究存在。此外，人们对地下土壤中碳的长期稳定和储存过程还不够了解。土壤管理一直导致有机物埋藏。自12世纪以来，农田被广泛地管理为垄沟系统。随着模板向一个方向耕作，山脊被建立起来，将以前的表土埋在下面。随着蒸汽犁的发明，耕作深度不断增加。深耕已用于灰壤和陆壤的土壤改良，后来也用于泥炭地的耕作。20世纪60年代，在德国北部开展了数十项深耕农业田间试验。该项目的目的是：1)比较有机质埋藏对土壤碳储量的长期影响，从而分析农业（10个地点）、林业（5个地点）和化石农田（5个山脊和犁沟地点）的深耕对气候的影响。在配对样地法中，土壤碳储量被量化至150厘米深。2)研究埋地碳长期稳定和储存的机制和过程。除了分析控制碳储存的主要土壤特定驱动因素外，还将使用分馏方案分析碳稳定程度，分馏方案必须进一步发展，以便也适用于底土。3)通过放射性碳分析确定有机质埋藏对深耕土壤和可比非深耕土壤碳周转速率的影响。20世纪60年代的核弹试验使大气中的14C浓度增加了一倍，14C可以作为深耕试验中新埋碳的示踪剂。埋藏碳和非埋藏碳的潜在生物利用度是在培养实验中确定的。连同土壤生态参数，如微生物生物量和代谢比率，它们提供了对底土微生物生活条件的深入了解。因此，有机质埋藏可以作为研究地下土壤百年碳储存的潜在机制的实验装置，并通过有针对性的土壤管理来量化地下土壤储存碳的潜力。

Increased carbon sequestration in soils is acknowledged as climate mitigation measure to reduce atmospheric CO2. Until now, research and praxis have focused on reduced and no-tillage even though their effects on soil carbon stocks of soils are marginal. The option of organic matter burial to enhance carbon storage in agriculture and forestry has been overlooked so far and almost no studies exist. Moreover, the processes of long-term stabilisation and storage of carbon in subsoils is insufficiently understood.Soil management has always led to organic matter burial. Croplands have been widely managed as ridge and furrow systems since the 12th century. With mouldboard ploughing into one direction, ridges were built up and buried former topsoil underneath. With invention of the steam plough the ploughing depth was continuously increased. Deep ploughing has been used for soil melioration in Podsols and Luvisols and later on also in peatland cultivation. During the 1960s dozens of agricultural field experiments on deep ploughing were set up in Northern Germany. The aims of the project are:1) to compare the long-term effect of organic matter burial on soil carbon stocks and thus, its climate impact analysing deep ploughing in agricultural (10 sites) and forestry (5 sites) and fossil cropland (5 ridge and furrow sites). In a paired plot approach soil carbon stocks are quantified down to 150 cm depth.2) to investigate the underlying mechanisms and processes of long-term stabilisation and storage of buried carbon. In addition to analysis of the main soil specific driving factors that control carbon storage, the degree of carbon stabilisation is going to be analysed using fractionation schemes that have to be further developed to be applicable also for subsoils.3) to determine the effect of organic matter burial on carbon turnover rates via radio carbon analysis on deeply ploughed soils and comparable not deeply ploughed soils. Nuclear bomb tests during the 1960s doubled the atmospheric 14C concentration which can be used as tracer for the freshly buried carbon at the deep plough trials. Potential bioavailability of buried vs. non-buried carbon are determined in incubation experiments. Together with soil ecological parameters such as microbial biomass and the metabolic ratio they provide an insight into microbial life conditions in the subsoil.Thus, organic matter burial can be used as experimental set-up to investigate the underlying mechanisms of centennial carbon storage in subsoils and to quantify subsoil potential to store carbon via targeted soil management.