Roots are key agents in carbon (C) and nitrogen (N) biogeochemical cycles. They are the interface and main link between the plant and the soil in the rhizosphere. Organic C and N move from plant to soil via root mortality, where they either decompose or become part of the soil organic matter (SOM) until they eventually mineralize or are lost (i.e. via leaching or erosion).
Dynamic root growth is not considered in biogeochemical models, assumed as a constant or fixed ratio of the overall biomass or is dynamic simulated using fixed allocation factors. In addition, subsequent root decomposition, C and N dynamics, and nutrient turnover, are frequently modelled with time as the single dependent variable, and without further consideration of other influencing modifications or processes. Soil heterogeneity is also frequently ignored in C and N biogeochemical models, which consider the soil as a single unit and ignore its horizontal and vertical heterogeneity, aside from soil type and quality. However, these simple views are challenged by empirical evidence that suggests that crucial processes might be neglected in the available approaches. Furthermore quantification of the error of uncertainty of total root C and N, root decomposition and C and N mineralization is hardly ever reported.

Climate change (CC) may lead to a change in plant C allocation, decomposition and mineralization patterns, but there is limited understanding about the response of roots to CC. Little is known about the impact of drought, extreme events or nutrient limitation on rhizosphere processes. It is time to improve our knowledge of root-soil interactions, and to understand the inner workings of this black box.
We encourage motivated researchers to submit abstracts addressing the issues of roots as part of the carbon and nitrogen cycles in arable, grassland, forest and natural ecosystems. Both empirical studies and model approaches are welcome. We are especially interested in contributions concerning growth allocation factors, impacts of climate change on the root fraction and its interaction with climate and the plant root. We are also especially interested in the impact of climate extremes on root growth and model approaches for simulating root growth in ecosystems, or related topics