Capability, a term that has been well defined in welfare economics, can be applied to soil by defining the intrinsic capacity of a soil to contribute to ecosystem services, including biomass production. Seven soil functions are used to define capabilities, and combining different functions in storylines provides integrated expressions for capability considering the different functions. Applied to biomass production in a sustainable production system, potential production (Yp) is defined as a function of radiation, temperature, CO2 and plant physiology. Yp is independent of soil and provides an absolute point of reference. Yw represents water-limited yield, reflecting actual water regimes and assuming that soil fertility is adequate and pests and diseases don’t occur. Ya represents actual yield. A soil capability index (SCI) is defined as SCI = (Ya/Yw) × 100 for a biomass production storyline for rainfed production systems. Some examples are presented. Using simulation modelling, Yp can be simulated for a given climate and Yw can be simulated for a given soil in a probabilistic manner using weather data for 30 years as a form of quantitative land evaluation. Ya can be measured. Not only capability, as such, is important, however, but also the way in which capability can be realized under practical conditions. Then, a management support system is needed to guide a farmer real time through the growing season, also taking into account long-term effects. Capability is defined for a given type of soil (the genoform), but sometimes management has had significant effects on soil properties, requiring a phenoform approach, as is illustrated.