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Studies about water flow and solute transport processes evolving in the soil-plant-atmosphere (SPA) system are now not only quite far from the pioneering activities on the concepts of field capacity, permanent wilting, and plant available water, but has also evolved from a set of agricultural and hydrologic applications focusing on problems at different spatial and temporal scales. Evidence for that is the far-reaching stimulus, both experimental and theoretical, offered by engineers and hydrologists, soil scientists, plant physiologists, ecologists, and climatologists.

At the beginning, monitoring of soil-water interactions and process dynamics in the SPA system have progressed on parallel but separate tracks with respect to the developments of modeling tools. There was also a sort of spatial scale mismatch between the former studies, mainly carried out at core and plot scales, and the latter activities, mainly devoted to the hillslope and catchment scales. As our ability to monitor the above mentioned processes shifted from the use of classic tensiometers and gravimetric water contents toward more sophisticated matric pressure and moisture sensors as well as remote sensing, there has been a huge effort to model dominant processes even better and in a more comprehensive way. Detailed and intensive monitoring has spurred mathematical descriptions from the smaller scale of root zone to the larger scale of an entire basin or irrigation district.

During the last few years, we are witnessing a growing convergence between the monitoring and modeling activities related to SPA processes. With a view to the above, it is timely to organize a conference that brings together researchers from different backgrounds to discuss the important achievements obtained thus far over the last decades, but also and perhaps especially to outline potential future directions for research being of benefit and interest to the younger generation.