According to this article, water flow processes in the soil-plant-atmosphere continuum, with particular emphasis on processes in the soil, have greatly enhanced understanding of the system, thereby enabling the formulation of a quantitative model relating the water supply from a layered soil profile to water demand; the formulation of logical quantitative definitions for crop-ecotope specific upper and lower limits of available water; the identification of the harmful root zone development effects of compacted layers in fine sandy soils caused by cultivation and amelioration procedures to prevent these effects; and management strategies to combat excessive water losses by deep drainage.