A conceptual model for analysing input±output coecients in arable farming systems: from diagnosis towards design T.J. de Koeijer a, * ,y , G.A.A. Wossink b,c , M.K. van Ittersum d , P.C. Struik d , J.A. Renkema c a Wageningen Agricultural University, Department of Plant Sciences, Biological Farming Systems Group, Haarweg 333, 6709 RZ Wageningen, The Netherlands b North Carolina State University, Department of Agricultural & Resource Economics, Raleigh, NC 27695-8109, USA c Wageningen Agricultural University, Department of Economics and Management, Hollandseweg 1, 6706 KN Wageningen, The Netherlands d Wageningen Agricultural University, Department of Plant Sciences, Bornsesteeg 47, 6708 PD Wageningen, The Netherlands Received 24 March 1998; accepted 8 April 1999 Abstract Environmental legislation is forcing a rethink about desirable crop production systems. The development of new production systems that meet economic and environmental objectives demands knowledge about which input±output combinations are feasible and optimal in practice. A review of concepts in agronomy and in farm and behavioural economics leads to a conceptual model with a division into production levels and accompanying production restricting factors. The highest production level can be de®ned by merely agronomic growth factors; the next production level is restricted by a mixture of economic and other agronomic factors. The two lowest levels are further restricted by taking into account the socio-psychological factors. With the production restricting factors of the conceptual model the dierences in agronomic eciency of actual and theoretical input±output combinations will be analysed in order to ®nd out which input±output combinations will be feasible and optimal in practice. # 1999 Elsevier Science Ltd. All rights reserved. Keywords: Sustainable farming systems; Input±output coecients; Agronomical eciency; Interdisciplinary analysis 1. Introduction Many European countries are in the process of developing legislation that aims at drastically reducing environmentally harmful emissions in order to achieve a more environment friendly agriculture. This process forces a rethink about land use and agricultural production practices. Farmers will have to adopt production systems incorporating new and modi®ed techniques. Rossing et al. (1999) distinguish four phases within the development of such production sys- tems: diagnosis, design, testing and improvement, and dissemination. An important part of the diagnosis phase should be devoted to analysis of input±output combinations of current production systems. By analysing the input±output combina- tions of the actual ecient production techniques and the theoretical ones, insight can be gained in which production techniques will be feasible and optimal in practice. 0308-521X/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S0308-521X(99)00030-X Agricultural Systems 61 (1999) 33±44 www.elsevier.com/locate/agsy * Corresponding author. Tel.: +31-317-48-4735; fax: +31- 317-48-4575. y Present address: LEI-DLO Detachment Wageningen, P.O. Box 35, 6700 AA Wageningen, The Netherlands E-mail address: t.j.dekoeijer@lei.dlo.nl (T.J. de Koeijer)