CORE IDEAS: Contributions are mainly from the 2017 International Soil Physics Workshop in China. Soils are fundamental in supplying food, energy, water (FEW), and ecosystem services. Interdisciplinary (convergence) approaches are needed to address FEW challenges. Soils are foundational to sustaining the food, energy, and water (FEW) systems and provide many essential ecosystem services. Soil degradation is a major threat to food security in China and elsewhere in the world. It is critical to advance soil science to improve the FEW systems so that FEW supplies can be provided to human populations in a sustainable and resilient manner. To do so, we must understand interactions among soil physical, chemical, and biological processes, as well as the role, function, and contribution of soil physical processes to delivering FEW supplies and ecosystem services. Soil processes and crop production are strongly controlled by physical processes such as soil water flow, aggregate stability, compaction, heat regime, irrigation and drainage, soil aeration, etc. Recognizing the importance of soil physics to the nexus of FEW systems, the collection in this special section mainly includes research presented at the International Workshop of Soil Physics and the Nexus of Food, Energy, and Water held on 3–5 Aug. 2017 at Shenyang, China. This special section covers diverse topics including fundamental soil physical properties and water flow, land use and agricultural management, soil organic carbon management, soil physical modeling, and transport of emerging contaminants. More future research using interdisciplinary (nexus or convergence) approaches should be undertaken to address challenges in many contemporary and emerging FEW issues.

Aside from the many services that soil provides, it also stores water and makes it available to crops, which is critical for food security. However, the necessity of further studies for overcoming the existing gap in relation to the role of soil in the water, energy, and food nexus system has been preoccupying the experts and specialists around the world for some time. In this sense, the balance between many key ecosystem components based on the Soil, water, energy, and food (SWEF) nexus framework is one of the key characteristics of holistic and accommodative watershed management systems. To the best of our knowledge, the watershed scale is used as a planning unit for the first time in the current study to construct a conceptual model for adaptive management of optimum land-use/cover allocation using SWEF. The method was then used for the Shazand Watershed, Iran. Numerous metrics, such as soil erosion, soil organic carbon (SOC), water and energy use, mass efficiency, and economic efficiency, were investigated. Finally, a compound indicator was used to generate the SWEF nexus index (SWEFNI) for various land-uses/crops for the node year 2014. SWFENI ranged from 0.19 (worst) for rangeland to 0.78 (best) for almond plantations, according to the findings. The study's present approach may be tested worldwide.