Opportunistic Mediterranean agriculture – Using ephemeral pasture legumes to utilize summer rainfall Dion L. Nicol a,b,⇑ , John Finlayson b,c,d , Timothy D. Colmer a , Megan H. Ryan a,b a School of Plant Biology and Institute of Agriculture (M084), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia b Future Farm Industries Cooperative Research Centre (M081), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia c School of Agricultural and Resource Economics (M089), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia d EH Graham Centre, Charles Sturt University and Department of Primary Industries, Wagga Wagga Agricultural Institute, Pine Gully Road, Wagga Wagga, NSW 2650, Australia article info Article history: Received 29 March 2012 Received in revised form 19 February 2013 Accepted 1 June 2013 Available online 2 July 2013 Keywords: Low-rainfall environments Climatic variability Cullen species Novel plants Crop and pasture residues Bio-economic modeling abstract The wet winters and summer droughts of dry Mediterranean-type climates create a highly seasonal sup- ply of feed for livestock. Much of the forage value of winter-active annual pastures and crop residues is realized as dry feed during summer–autumn. Sporadic summer–autumn rainfall rapidly degrades the quality of dry plant residues. In low rainfall areas of the southern Australian wheatbelt, there are no well-adapted crops or pastures to convert summer rainfall into high-quality green feed and supplemen- tary feeding is required to maintain livestock condition. We therefore investigated two undomesticated ephemeral legumes (Cullen cinereum and Cullen graveolens). In a field experiment, the ephemerals were dormant in winter–spring and responded strongly to summer rainfall, with 0.45–0.82 t ha –1 of shoot dry weight produced over summer. Extrapolation of regional historic rainfall records showed similar or greater summer–autumn rainfall in 40% of years and also suggested that conditions will probably be too dry for perennial pastures such as Medicago sativa (lucerne) to persist in up to 60% of years. An analysis using MIDAS, a bio-economic model, suggested that ephemerals could increase total farm profit and stocking rates (10.3% and 7.7%, respectively), and decrease supplementary feeding of grain by >50% by providing high quality feed in years that summer–autumn rainfall occurs. We suggest there is consid- erable potential for ephemeral legumes to contribute to the sustainability of mixed agriculture in dry Mediterranean-type climates by utilizing sporadic summer rainfall whilst complementing existing annual pasture and cropping systems. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Strongly seasonal environments present constraints to livestock systems due to peaks and troughs in feed quantity and quality. The present study focused on low-rainfall zones in dry Mediterranean- type climates which are characterized by hot, dry summers and mild, wet winters. Although characterized by a long, dry summer period, thunderstorms and degraded tropical cyclones can bring episodic summer–autumn rainfall to these regions, at least in Aus- tralia. Agricultural areas that receive infrequent summer–autumn rainfall events generally do not convert rainfall into additional for- age due to a lack of profitable, commercial summer-forage options and poor persistence of summer-active perennial pastures. Livestock in Mediterranean farming systems that are based on winter-active annual plants rely on dry plant residues during sum- mer–autumn (Puckridge and French, 1983). When dry plant resi- dues get wet, they rapidly degrade due to microbial activity and leaching of soluble nutrients. Rossiter et al. (1994) found single thunderstorms during summer can reduce the digestibility of high-quality dry pasture residues below those required for main- taining livestock condition. Brown (1977) reported different degra- dation rates among plant types, with high-feed-value legume residues degrading the most rapidly once wet. Thus, for livestock systems, supplementary feeding or alternate high-quality feed sources are required if summer–autumn rainfall occurs. Although summer–autumn rainfall in dry Mediterranean-type environments such as south-western Australia is considered to provide little opportunity for plant growth due to high evaporation and temperatures, summer rainfall contributes to weed growth that can often be deleterious to stock (e.g. Tribulus terrestris, Aslani et al., 2003) or self-sown crop plants that increase the risk of dis- ease carry-over to following crops (Roget et al., 1987). Summer-ac- tive weeds complete their entire life-cycles in dry Mediterranean- type environments in response to episodic rain events during sum- mer–autumn. This demonstrates that at least some forage produc- tion is possible even with very infrequent rainfall, providing suitably–adapted plants possess adequate forage quality. Plants with such short growth seasons, and which may be absent most years, are often referred to as ephemerals. 0308-521X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.agsy.2013.06.001 ⇑ Corresponding author. Tel.: +61 8 6488 1936; fax: +61 8 6488 1108. E-mail address: dion.nicol@uwa.edu.au (D.L. Nicol). Agricultural Systems 120 (2013) 76–84 Contents lists available at SciVerse ScienceDirect Agricultural Systems journal homepage: www.elsevier.com/locate/agsy