Soil structure is important in the air-soil-water continuum for air- and water- exchange, transport of chemicals and micro-organisms, and root growth. Macro-scale soil structure consists of interpedal porosity, shrinkage fractures, and biochannels; whereas micro-scale soil structure depends more on clay mineralogy, properties of soil organic matter, and microbial activity. These components of soil structure change in response to soil water content, bio-activity, and applied external load. Soil structure not only varies across scales but often within the vertical profile. Although in the past soil had been considered homogeneous, soil structure is now often considered directly or indirectly in models of water flow and solute transport, and of root growth. In most cases, the soil structural aspects are considered a static model input. The objective of this session is to explore ways of describe dynamic aspects of soil structure and incorporate this knowledge into models of the whole system. Knowledge gaps will be delineated and techniques proposed to understand, synthesize, and quantify these gaps.