Economic and environmental implications of wheat-crop sequences on organic dairy-farm simulations D. C. Abreu A,E,G , A. K. Hoshide B , E. B. Mallory C , E. H. Roche C , A. S. Oliveira A , R. J. Kersbergen D , R. P. Lana E , and M. A. Fonseca F A Instituto de Ciências Agrárias e Ambientais, Universidade Federal de Mato Grosso, Avenida Alexandre Ferronato, 1200, Sinop, MT 78557-267, Brazil. B School of Economics, University of Maine, 5782 Winslow Hall, Orono, ME 04469, USA. C Cooperative Extension and School of Food and Agriculture, University of Maine, 495 College Avenue, Orono, ME 04473, USA. D University of Maine Cooperative Extension, 992 Waterville Road, Waldo, ME 04915, USA. E Departamento de Zootecnia, Universidade Federal de Vi¸ cosa, Vi¸ cosa, MG 36570-900, Brazil. F Department of Agriculture, Nutrition & Veterinary Sciences, 214 Sarah H. Fleischmann Bldg., University of Nevada, Reno, NV 89557, USA. G Corresponding author. Email: abreu@ufmt.br Abstract. The market for high-quality organic bread wheat (Triticum aestivum L.) is increasing in New England, USA, providing opportunities for organic dairy farmers to grow this alternative cash crop. Our objective was to determine the sustainability of eight 3-year crop sequences compared with a perennial forage baseline in long-term (25-year), well- managed, medium-sized organic dairy farm simulations. Systems included wheat (spring or winter) preceded by maize (Zea mays L.) silage, a 1-year-old perennial forage grass, or soybean as well as maize silage followed by maize silage or soybean. Farm net return was highest for the entirely grass-based system (US$742.15 cow –1 ). Higher winter wheat yields for soybean–wheat–grass resulted in 7% more income from feed sales ($1027) than spring wheat. Soybean followed by wheat reduced soil nutrient accumulation by 0.8 kg ha –1 year –1 for phosphorus runoff and leachate losses and for potassium accumulation (–17%); there was also a 4% reduction in water footprint (kg kg –1 fat- and protein-corrected milk). Growing winter wheat provides long-term environmental and economic benefits, although for spring wheat, much of this benefit is lost. Use of maize silage in place of grass, winter or spring wheat, or soybean was less profitable. Most cropping system scenarios were less economically favourable than producing and feeding exclusively grass silage. However, inclusion of soybean increased economic benefits. Additional keywords: agricultural modelling, corn, integrated farm system model, sustainability, whole-farm system. Received 27 July 2015, accepted 2 May 2016, published online 26 September 2016 Introduction The organic food market has expanded in North America (Lotter 2003; McBride and Greene 2009) and Europe (Cederberg and Mattsson 2000; David et al. 2012). One reason for the expansion of this market is the pool of consumers demanding the often longer term sustainability of organic production compared with conventional systems (O’Hara and Parsons 2013), when organic food is based on ecological production systems integrating cultural, biological, and mechanical practices that improve cycling of resources, promote ecological balance, and conserve biodiversity (Underwood et al. 2011). In the north-east of the United States, the demand for local organic bread wheat (Triticum aestivum L.) is growing. This market niche provides a great opportunity for organic dairy farmers in the New England area. In Europe, organic cereal prices can be twice conventional prices when used for human nutrition, whereas organic cereal prices can be 30% more than conventional when used as animal feed (David et al. 2012). Even though some organic dairy producers have included wheat in their crop rotations, integrating wheat into these dairy cropping systems faces several technical challenges. First, although expanding their rotation increases crop and species diversity, the greater management required for the more complex rotations can be challenging for producers. Second, the productivity (yield and quality) of organic wheat is restricted by the availability of nitrogen (N) for plant uptake (Olesen et al. 2002; David et al. 2005). Third, studies have shown lower protein content for organic than conventional wheat (Carcea et al. 2006; Mäder et al. 2007; Zörb et al. 2009) because organic producers supply N through sources such as animal Journal compilation Ó CSIRO 2016 www.publish.csiro.au/journals/cp CSIRO PUBLISHING Crop & Pasture Science, 2016, 67, 1127–1138 http://dx.doi.org/10.1071/CP15250