Economic and environmental implications of wheat-crop sequences on organic dairy-farm simulations

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.