Professional urban urban agriculture and its characteristic business models in Metropolis Ruhr, Germany

'Low-cost specialization', 'differentiation', and 'diversification' are three overarching business models of professional urban agriculture in developed countries. Manifold city-adjusted farm activities belong to these business models resulting in the characteristic farm heterogeneity of urban areas. This paper makes use of the business models as tool for a geo-statistical analysis to spatially investigate farming patterns in reference region Metropolis Ruhr, Germany. Additional farm interviews substantiate findings of the geo-statistical analysis by focusing on horticulture as a common farm activity towards `low-cost specialization', direct marketing and participatory farming belonging to 'differentiation', and equestrian services as a representative of the 'diversification' business model. These farm activities and underlying business models concentrate and tend to spatially cluster in the metropolitan's center where population density is highest and farmland proportion is lowest. Agriculture plays a significant role in Metropolis Ruhr cultivating about one-third of the metropolitan area, but on-going loss of farmland and short-term lease of land affect farms considerably by complicating access to land. Most differentiated and diversified farms require certain amount of farmland to be successful, which is threatened by further farmland losses along with increased competition for the remaining farmland. Long-term planning security is crucial for farms focusing on high added value crops and organic farming, Progressively emerging participatory farming activities demonstrate urban farms' abilities to innovatively adapt to societal demands. Better knowledge on professional urban agriculture's farm activities and business models is of importance for farms and their related advisory services to address the urban context in farm development strategies more accurately, but also for public authorities' planning and policies in land-related decision making. Economic viability of professional urban agriculture is the key requirement for additional social, environmental, and landscape functions within urban areas. (C) 2016 Elsevier Ltd. All rights reserved.