Ecosystems integrity and services are threatened by anthropogenic global changes. Mitigating and adapting to these changes require knowledge of ecosystem functioning in the expected novel environments, informed in large part through experimentation and modelling. This paper describes 13 advanced controlled environment facilities for experimental ecosystem studies, herein termed ecotrons, open to the international community. Ecotrons enable simulation of a wide range of natural environmental conditions in replicated and independent experimental units while measuring various ecosystem processes. This capacity to realistically control ecosystem environments is used to emulate a variety of climatic scenarios and soil conditions, in natural sunlight or through broad‐spectrum lighting. The use of large ecosystem samples, intact or reconstructed, minimizes border effects and increases biological and physical complexity. Measurements of concentrations of greenhouse trace gases as well as their net exchange between the ecosystem and the atmosphere are performed in most ecotrons, often quasi continuously. The flow of matter is often tracked with the use of stable isotope tracers of carbon and other elements. Equipment is available for measurements of soil water status as well as root and canopy growth. The experiments ran so far emphasize the diversity of the hosted research. Half of them concern global changes, often with a manipulation of more than one driver. About a quarter deal with the impact of biodiversity loss on ecosystem functioning and one quarter with ecosystem or plant physiology. We discuss how the methodology for environmental simulation and process measurements, especially in soil, can be improved and stress the need to establish stronger links with modelling in future projects. These developments will enable further improvements in mechanistic understanding and predictive capacity of ecotron research which will play, in complementarity with field experimentation and monitoring, a crucial role in exploring the ecosystem consequences of environmental changes.

Thorough knowledge of root system functioning is essential to understand the feedback loops between plants, soil, and climate. In situ characterization of root systems is challenging due to the inaccessibility of roots and the complexity of root zone processes. Electrical methods have been proposed to overcome these difficulties. Electrical conduction and polarization occur in and around roots, but the mechanisms are not yet fully understood. We review the potential and limitations of low‐frequency electrical techniques for root zone investigation, discuss the mechanisms behind electrical conduction and polarization in the soil–root continuum, and address knowledge gaps. A range of electrical methods for root investigation is available. Reported methods using current injection in the plant stem to assess the extension of the root system lack robustness. Multi‐electrode measurements are increasingly used to quantify root zone processes through soil moisture changes. They often neglect the influence of root biomass on the electrical signal, probably because it is yet to be well understood. Recent research highlights the potential of frequency‐dependent impedance measurements. These methods target both surface and volumetric properties by activating and quantifying polarization mechanisms occurring at the root segment and cell scale at specific frequencies. The spectroscopic approach opens up a range of applications. Nevertheless, understanding electrical signatures at the field scale requires significant understanding of small‐scale polarization and conduction mechanisms. Improved mechanistic soil–root electrical models, validated with small‐scale electrical measurements on root systems, are necessary to make further progress in ramping up the precision and accuracy of multi‐electrode tomographic techniques for root zone investigation.

Agriculture is facing immense challenges. We have to produce enough food while safe‐guarding the environment for future generations. This results in the need to use less water and fertilizer, and to harness soil quality. Key to achieving this goal is improving the understanding of processes and interactions governing the soil–plant–atmosphere continuum of agricultural ecosystems. Geophysical tools have great potential to better characterize and quantify these processes noninvasively from the plot to landscape scale. Nevertheless, a number of challenges remain for geophysical results to be better exploited by different scientific communities and by decision‐makers. In this special section, we explore ongoing research in the relatively new field of agrogeophysics, and we provide an overview of potential applications and highlight future research needs.

Adopting soil and crop management practices that conserve or enhance soil structure is critical for supporting the sustainable adaptation of agriculture to climate change, as it should help maintain agricultural production in the face of increasing drought or water excess without impairing environmental quality. In this paper, we evaluate the evidence for this assertion by synthesizing the results of 34 published meta-analyses of the effects of such practices on soil physical and hydraulic properties relevant for climate change adaptation in European agriculture. We also review an additional 127 meta-analyses that investigated synergies and trade-offs or help to explain the effects of soil and crop management in terms of the underlying processes and mechanisms. Finally, we identify how responses to alternative soil–crop management systems vary under contrasting agro-environmental conditions across Europe. This information may help practitioners and policymakers to draw context-specific conclusions concerning the efficacy of management practices as climate adaptation tools. Our synthesis demonstrates that organic soil amendments and the adoption of practices that maintain “continuous living cover” result in significant benefits for the water regulation function of soils, mostly arising from the additional carbon inputs to soil and the stimulation of biological processes. These effects are clearly related to improved soil aggregation and enhanced bio-porosity, both of which reduce surface runoff and increase infiltration. One potentially negative consequence of these systems is a reduction in soil water storage and groundwater recharge, which may be problematic in dry climates. Some important synergies are reductions in nitrate leaching to groundwater and greenhouse gas emissions for nonleguminous cover crop systems. The benefits of reducing tillage intensity appear much less clear-cut. Increases in soil bulk density due to traffic compaction are commonly reported. However, biological activity is enhanced under reduced tillage intensity, which should improve soil structure and infiltration capacity and reduce surface runoff and the losses of agro-chemicals to surface water. However, the evidence for these beneficial effects is inconclusive, while significant trade-offs include yield penalties and increases in greenhouse gas emissions and the risks of leaching of pesticides and nitrate. Our synthesis also highlights important knowledge gaps on the effects of management practices on root growth and transpiration. Thus, conclusions related to the impacts of management on the crop water supply and other water regulation functions are necessarily based on inferences derived from proxy variables. Based on these knowledge gaps, we outlined several key avenues for future research on this topic.