Aspects of Applied Biology 128, 2015 Valuing long-term sites and experiments for agriculture and ecology 57 Yield stability of grain legumes in an organically managed monitoring experiment By MORITZ RECKLING 1,2 , THOMAS F DÖRING 3 , KARIN STEIN-BACHINGER 1 , RALF BLOCH 1 and JOHANN BACHINGER 1 1 Leibniz Centre for Agricultural Landscape Research (ZALF), Institute of Land Use Systems, Eberswalder Str. 84, 15374 Müncheberg, Germany 2 Department of Crop Production Ecology, Swedish University of Agricultural Sciences (SLU), Box 7043, 75007 Uppsala, Sweden 3 Humboldt University Berlin, Department of Agronomy and Crop Science, Albrecht-Thaer-Weg 5, 14195 Berlin, Germany Corresponding Author Email: Moritz.Reckling@zalf.de Summary Grain legumes play a key role as a protein source and in cropping systems but their yields are perceived to luctuate more than other crops. Therefore, an organically managed experiment on a research station in Northeastern Germany with eight monitoring trials from 1993 to 2013 was used to assess yields of two grain legume species (narrow-leafed lupin and ield pea), two winter cereals (rye and wheat) as well as spring oats and silage maize. Two orthogonal data sets were analysed to compare individual grain legumes with cereals and silage maize in terms of temporal yield stability. Both grain legumes showed lowest average yields and lowest yield stability among the crop species; this was the case for both variance and regression type stability parameters. Causes for the low stability of grain legumes are still insuficiently known. Long- and short-term strategies need to be developed to reduce and adapt to high yield luctuations of grain legumes in cropping systems. Key words: Grain legume, land use change and impact, lupin, pea, yield stability Introduction Grain legumes play a key role as a protein source and in cropping systems because of their various agronomic, environmental and farm-economic beneits (Preissel et al., 2015; Reckling et al., 2014). However, areas of grain legumes under cultivation have declined in Europe in recent decades from 4.7% in 1961 to 1.7% in 2013 (FAOstat, 2014) due to agronomic and marketing constraints and an increased specialisation of farms. Currently, less than 30% of plant-based protein feed is produced within Europe, so protein security is an issue, and at the same time rotations have become less diverse and questions about their sustainability are often raised. To enhance grain legume cultivation in Europe current constraints need to be addressed. A repeatedly stated problem for grain legume production is low yield stability; in fact, yield luctuations are one of the main reasons farmers give for not growing these crops (von Richthofen et al., 2006). Climate change might even increase the conditions that cause yield luctuations and therefore a deeper understanding of the magnitude and causes are required. So far, however, little quantitative