Environmental relevanceThe SCM view

Environmental relevance

The SCM view of the nature of soil organic matter—which excludes any secondary synthesis of ‘humic substances’—has implications for a range of disciplines that build on the science of organic matter properties and changes in soil (Fig. 1). This is all the more important as the ‘humic substances’ concept is very widely adopted outside the soil sciences, with the majority of publications focusing on ‘humic substances’ published in journals that do not explicitly cover soil science.

Soil carbon modelling

Soils contain more organic carbon than the atmosphere and vegetation combined1 and predictions of soil organic matter dynamics could there-fore greatly influence forecasts of global climate change. Major soil carbon models such as Century54 or RothC55 are built on the premise that soil organic matter can be divided into pools that have different turnover times. None of these models explicitly represents the characteristic pro-cesses of carbon transformation detailed in the SCM, such as adsorption and protection, desorption, and microbial activity. Although carbon movement between pools and their decomposition rates are modified by temperature, texture and moisture, the default turnover rates asso-ciated with individual carbon pools are justified by the combined influ-ence of physical protection and an inferred resistance to decomposition that is dependent on substrate quality (‘quality’ is here used in the sense of molecular composition of the organic matter). Particularly for the ‘slow’ and ‘passive’ pools, this inherent resistance to decomposition (recalcitrance) has been understood to be the result of ‘humification’, with the RothC model explicitly including ‘humus’ fractions55. Lack of mech-anistic representation of the decomposition process produces disagree-ment among models56 and between model predictions and observational data
The shortcomings become apparent when these models are applied to predict the global warming feedback of soil organic carbon miner-alization. Rising temperatures increase microbial activity and a warm-ing atmosphere may therefore lead to greater mineralization of soil organic carbon59. The resultant carbon dioxide emissions would then accelerate the greenhouse effect and thereby increase global temper-ature. Soil organic matter pools with slower turnover are thought to respond more sensitively to climate warming than those with fast turn­ over59–61. The underlying, so-called carbon–quality–temperature theory (CQT theory62) combines classical ‘humification’ theory, that is, the assumption that decomposition creates complex, recalcitrant compounds, with the Arrhenius theory that chemical reactions are faster at higher tem-peratures63. According to CQT theory, the decomposition of a complex substrate requires more enzymatic reactions and a higher total activation energy than a reaction metabolizing a simple carbon substrate, and as a result, would be more sensitive to rising temperatures than the decom-position of a simple carbon substrate. The CQT theory loses much of its explanatory potential for the carbon pools with slow turnover if the decomposition of organic matter is not creating complex and recalcitrant compounds.

Different organic compounds entering the soil have highly varying composition 64 and in isolation (for example, fresh litter) have differ-ent turnover and hence temperature responses as a function of their composition60 . However, this variation is so heavily influenced by environmental and biotic factors after they enter the soil ecosystem that the concept of relying on quality-dependent temperature responses is, in our opinion, obsolete. We propose that future research should concentrate to a much greater extent on the causes of any observed substrate prefer-ences, such as the absence of a decomposer with a matching catabolic toolbox or the lack of a critical resource for the decomposer.

Results (Chinese) 1:

环境的相关性供应链管理视图的土壤有机质性质 — — 其中不包括任何辅助合成 '腐殖物质' — — 已对一系列学科基础的科学的有机物质的性质和土壤 (图 1) 的变化的影响。这是作为 '腐殖物质' 的概念很广泛采用外土壤科学，与大多数的专注于 '腐殖物质' 在不显式包括土壤科学的期刊上发表的出版物更重要。土壤碳建模土壤含有更多的有机碳比的气氛和植被的 combined1 和预测土壤有机物质动力学可能因此大大影响对全球气候变化的预测。主要土壤碳如 Century54 或 RothC55 模型的前提下，土壤有机质可分为池有不同的周转时间。没有这些模型可以明确地表示特征瞬间的碳转化、 吸附、 解吸和保护微生物活性等供应链管理中详细说明。虽然碳运动池和其分解率之间改性温度、 纹理和水分，默认更替率 asso 就是与个人碳池合理的物理保护和推断的抗性是依赖于承印物上质量的分解组合逐一 （'质量' 这里使用意义上的有机物质的分子组成）。特别是 '慢' 和 '被动' 池，分解 （顽固） 这固有的抵抗已被理解为是腐殖化'，用 RothC 模型显式包括腐殖质 fractions55 的结果。分解过程的机甲 anistic 表示缺乏产生不同意发展 models56 和模型预测与观测数据之间当这些模型进行预测，预测全球变暖反馈的土壤有机碳的矿工化缺点变得明显。气温上升增加微生物活性和温暖 ing 气氛因此可能会导致更大的成矿作用土壤有机 carbon59。由此产生的二氧化碳排放量将再加速温室效应，从而增加全球温度。土壤有机质池慢营业额被认为更敏感地回应气候变暖比那些快速转身 over59-61。底层的所谓碳 — — 质量 — — 温度理论 (复方七芍降压片 theory62) 结合古典 '腐殖化理论，那就是，分解创建复杂的、 顽固的化合物，具有化学反应都是在较高的透射电镜 peratures63 更快的阿伦尼乌斯理论的假设。复方七芍降压片理论的复合基质分解需要多酶反应和总激活能量高于代谢简单碳基体，反应和结果，会对气温上升比简单碳基体迪康位置更敏感。复方七芍降压片理论损失很大碳库与周转缓慢其解释性潜力如果有机物的分解不创建复杂和顽固的化合物。不同有机物进入土壤有高度不同组成 64，在隔离 （例如，新鲜垃圾） 有不同的营业额，从而为他们的 composition60 函数的温度响应。然而，这种变化是如此深受环境和生物因素后他们进入依靠质量依赖于温度响应的概念是，在我们看来，过时的土壤生态系统。我们建议未来的研究应集中于较大的程度任何的上观察到衬底更喜欢两者，缺乏的是分解者提供了一个匹配的分解代谢工具箱或分解者的重要资源的缺乏等原因。

Results (Chinese) 3:

环境关联从土壤有机质的性质，不包括任何二次合成的“腐殖物质”的管理视图的一系列学科，建立在科学的有机物性质和土壤的变化（图1）的影响。这是更重要的，因为“腐殖物质”的概念是非常广泛的土壤科学以外，与大多数的出版物，专注于“腐殖物质”发表在期刊上没有明确覆盖土壤科学。土壤碳模型土壤有机碳比大气和植被combined1和土壤有机质的动态预测可能因此大大影响全球气候变化的预测控制。主要土壤碳模型如century54或rothc55是建立在土壤有机质可分为有不同的周转时间池的前提。这些模型都没有明确表示的特征过程碳转化在单片机的详细，如吸附和解吸，和微生物活性的保护。虽然池及其分解率之间的运动是碳改性温度、质地、水分、默认的周转率伴有单个碳池的物理保护的联合影响，推测抗分解，是依赖于基质质量证明（质量是这里使用的有机物质的分子组成感）。特别是对"慢"和"被动"池，这种固有的抗分解（顽固）被理解为“化”的结果，明确包括“腐殖质”fractions55 RothC模型。对分解过程的机械艺术表示缺乏产生不同意在models56和模型的预测与观测数据之间的管理的缺点变得明显时，这些模型用于预测土壤有机碳矿化的全球变暖问题反馈。温度的上升增加微生物活性和温的气氛可能因此导致更大的矿化土壤有机carbon59。由此产生的二氧化碳排放量将加速温室效应，使全球温度升高。土壤有机质库周转较慢被认为反应更灵敏的气候变暖比快转­over59–61。潜在的，所谓的碳–质量–温度理论（CQT theory62）结合了古典的腐殖化”理论，即假设分解创建复杂的，顽固的化合物，化学反应在较高的tem-peratures63更快的阿伦尼乌斯理论。根据CQT理论，对复杂基质的分解需要更多的酶促反应和较高的总活化能比反应代谢简单碳基板，和作为一个结果，会比一个简单的碳基质的分解温度上升更敏感。CQT的理论就失去了它与周转慢的碳库解释潜在的有机物质的分解是不创建复杂和顽固的化合物。不同的有机物进入土壤有非常不同的成分64和隔离（例如，新鲜垃圾）有不同的周转，因此温度响应作为他们composition60功能。然而，这种变化是如此严重影响环境和生物因素后，他们进入土壤生态系统，依赖于质量依赖性的温度响应的概念，在我们看来，过时的。我们建议未来的研究应该集中在更大的程度上观察到任何衬底的原因的喜好，如用一个匹配分解工具箱或为分解者分解关键资源缺乏的情况下。