Conserving soil carbon (C) and harnessing the potential for soil C sequestration requires an improved understanding of the processes through which organic material accumulates in soil. Currently, competing hypotheses exist regarding the dominant mechanisms that control soil C accumulation and transfers to mineral-associated pools. Long-standing hypotheses rely upon an assumed strong relationship between the quantity of organic inputs and soil C accumulation, while more recent hypotheses have shifted the focus towards the more complex controls of root activity, microbial processing and priming, and organo-mineral complexation. The Detrital Input and Removal Treatment (DIRT) experiment can test these competing hypotheses through field manipulations of detrital inputs. After 20 years of detrital manipulations in the wet, temperate forest of the H.J. Andrews Experimental Station, we found that with the termination of live root activity, the significant influx of dead root material and absence of soil priming by roots led to decreases in particulate organic matter (POM), but increases in stable mineral associated organic matter (MAOM). This suggests that soil mineral particles in undisturbed soils are not saturated with C in the presence of live roots and that pools of MAOM are sensitive to the balance between microbial-induced stabilization and microbial-induced priming and destabilization. Twenty years of aboveground litter removal did not change bulk soil C stocks or pools. Soil C stabilization did not increase in response to increases in high quality litter inputs, in contrast to recent theory, but in accordance with other empirical results. In contrast, increases in low quality wood litter led to a large increase in bulk soil C, with gains over 20 years confined to increases in POM. These findings offer insight into the pathways controlling soil C contents and provide potential explanations for the often-limited potential to increase mineral associated soil C in many vegetated soils and observed buffered responses of soil C stocks to disturbances such as drought, fire, and timber harvest.

节约土壤碳（C）并利用土壤固碳的潜力，需要对有机物质在土壤中积累的过程有更深入的了解。目前，关于控制土壤碳积累并转移到与矿物相关的池中的主要机制存在着相互竞争的假设。长期存在的假设依赖于有机输入量和土壤碳积累之间的假定的强关系，而最近的假设已将重点转移到了对根系活动，微生物加工和引发以及有机矿物质络合的更复杂控制上。碎屑输入和去除处理（DIRT）实验可以通过现场操作碎屑输入来测试这些相互竞争的假设。在HJ的潮湿温带森林中进行了20年的碎屑处理之后 安德鲁斯实验站（Andrews Experiment Station）发现，随着活根活动的终止，死根物质的大量涌入和根部对土壤的引发作用都没有，导致颗粒有机物（POM）减少，但稳定的矿物质相关有机物（MAOM）增加）。这表明在存在活根的情况下，原状土壤中的土壤矿物质颗粒不会被C饱和，并且MAOM池对微生物诱导的稳定与微生物诱导的引发和去稳定之间的平衡敏感。去除地上二十年的垃圾并没有改变土壤中的大量碳储量或储量。与最新的理论相反，土壤碳的稳定性并未因高品质垃圾投入量的增加而增加，但与其他实证结果一致。相比之下，劣质木材垫料的增加导致大量土壤C的增加，而20多年来的增加仅限于POM的增加。这些发现为控制土壤碳含量的途径提供了见识，并为增加许多植被土壤中与矿物相关的土壤碳的潜力往往有限提供了潜在的解释，并观察到土壤碳储量对诸如干旱，火灾和木材采伐等干扰的缓冲反应。